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Amplifier Characteristic
Please view these videos and we will discuss the topic in our next class. Please write your name and matric no. for your answer. To add comment , click the '+' button on the padlet . Made with a dash of wit :-)
Avatar of Jannah Ibrahim , PhD
Jannah Ibrahim , PhD
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MUHAMMAD ZUL
 MUHAMMAD ZULKARNAIN BIN ZAKARIA

1723395

SECTION 6

 

1.       Ideal Op Amp is when the input impedance (input resistance) is infinity and the output impedance (output resistance) equal to zero. Its implication to the input current and voltage, they will be block by this input impedance which is infinity.
 
2.       Input resistance is infinite.
Output resistance is zero.
Differential input voltage equal to zero.
Internal differential gain is infinite.
No current flow.
V1 – V2 = 0, V1=V2
So that it will give out maximum output voltage or current with such minimum input voltage or current.
 
3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.
 
4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.
 
5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.
 
6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.
 
7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.
 infinite.
No current flow.
V1 – V2 = 0, V1=V2
So that it will give out maximum output voltage or current with such minimum input voltage or current.
 
3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.
 
4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.
 
5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.
 
6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.
 
7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.

MUHAMMAD ZUL
 MUHAMMAD ZULKARNAIN BIN ZAKARIA

1723395

SECTION 6

 

1.       Ideal Op Amp is when the input impedance (input resistance) is infinity and the output impedance (output resistance) equal to zero. Its implication to the input current and voltage, they will be block by this input impedance which is infinity.
 
2.       Input resistance is infinite.
Output resistance is zero.
Differential input voltage equal to zero.
Internal differential gain is infinite.
No current flow.
V1 – V2 = 0, V1=V2
So that it will give out maximum output voltage or current with such minimum input voltage or current.
 
3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.
 
4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.
 
5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.
 
6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.
 
7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.

MUHAMMAD FAKHRUL HADI BIN ZAMZURI (1726963)
MUHAMMAD FAKHRUL HADI BIN ZAMZURI (1726963)
Q1) An ideal op amp is an op amp that has perfect conditions to allow it to function as an op amp with 100% efficiency. Ideal op amps will have infinite voltage gain, infinitely high impedance, zero output impedance, its gain is independent of input frequency, it has zero voltage offset, its output can swing positive or negative to the same voltages as the supply rails, and its output swings instantly to the correct value.
The implications of this ideal model in terms of input currents and voltages :
1. Infinite voltage gain
2. Infinite input impedance
3. Zero output impedance
4. Infinite bandwidth
5. Zero input offset voltage

Q2) Inverting amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. With the operational amp having such characteristics that are close to ideal, it is rather easy to design and build circuits using the IC op amp.
The characteristics of an ideal op-amp are as follows :
1. Infinite bandwidth due to the ideal gain inside of the op-amp
2. Infinite open-loop gain A
3. Infinite or zero common-mode gain
4. Input impedance of an infinite value
5. Output impedance of zero

Q3) In op-amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground. This concept is very useful in analysis of op-amp circuits and it will make a lot of calculations very simple.
This is how the virtual ground concept is employed in inverting amplifier :
Q4) Impedance is the relationship between voltage and current. It's a combination of resistance (frequency-independent, resistors) and reactance (frequency-dependant, inductors and capacitors).
An ideal op-amp has infinite input impedance. This means that there can be no current into or out of the inverting and non-inverting input terminals. 
An ideal op-amp has zero output impedance. This means that the output voltage is independent of output current.
To summarize, input impedance is "high" (ideally infinite). Output impedance is "low" (ideally zero).

Q5) The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.
In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V1, V2, V3, etc.

Q6) In this Non-inverting Operational Amplifier, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit we saw in the last tutorial whose output gain is negative in value. The result of this is that the output signal is “in-phase” with the input signal.
An ideal op-amp “No current flows into the input terminal” of the amplifier and that “V1 always equals V2”.

Q7) A voltage follower is a op-amp circuit which has a voltage gain of 1. The op amp does not provide any amplification to the signal and the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage.
An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used.
A voltage follower uses an op-amp to set the voltage on the output to be the same as the voltage on the input. It does however have limited drive capability
QUESTION 1: The ideal Op
 QUESTION 1:
The ideal Op Amp (Operational Amplifier) is a model that has three circuit element. It is a voltage controlled voltage source with very high gain. It is modeled with differential input terminals and has a single output terminal. The characteristics of an ideal amplifier are: 
Infinite voltage gain
Infinite input impedance
Zero output impedance
ANAS BIN KAMARUZZAMAN (1720979)
ANAS BIN KAMARUZZAMAN (1720979)
1. - An amplifier with infinite input impedance, infinite open-loop gain, zero output impedance and infinite bandwidth.
    - In the terms of input current, the input resistance of this ideal Op Amp is infinite, which can make the current in each input to be zero. 
    - In terms of voltage, the voltage gain is independent of the output current. 

2. - No Current Flows into the Input Terminals.
    - The Differential Input Voltage is Zero as V1 = V2 = 0

3. Voltage of a node that are almost equal to the virtual ground (V=0)

4. - To transfer all of the output voltage to the load.
    - When the voltage drops, it will amplify the signal.

5. - Ideal summing amplifiers is applied when the two or more different signals need to be combined.
    - These different signal sources will be added together by this amplifier.

6. Op-Amp is identified as non-inverting format when the output is in phase with the input signal. The signal is applied to the non-inverting input of the op-amp. The signal of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor is taken to ground. It must be applied to the inverting input as it is negative feedback.

7. A op-amp circuit which has a voltage gain of 1. The output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage

The advantages of such voltage follower circuit are:

- Very large input resistance, of the order of M
- Low output impedance, almost zero. Hence it can be used to connect high impedance source to a low impedance load, as a buffer.
- It has large bandwidth.
- The output follows the input exactly without Phase shift.

Muhammad aizul azim bin azham(1725809
Muhammad aizul azim bin azham(1725809
             1.Describe the ideal op-amp model

  -have infinite voltage gain
  -infinitely high impedance 
  -zero output impedance
  -its gain is independent of input frequency
  - has zero voltage offset
  -its output can swing positive or negative to the same voltages as the supply rails
   and its output swings instantly to the correct value.
 
 
4.What is the significance of zero output resistance
 
output impedance is zero because that's what amplifiers do.They convert a small signal into a larger one and  suppose the ratio of input to output impedance could be one measure of such. 
 

                5.decribe the operation and characteristics of ideal summing amplifier            

              n numbers of input terminal are connected in parallel. Here, in the circuit, the non-inverting                           

             terminal of the op amp is grounded, hence potential at that terminal is zero. As the op amp is 

              considered as ideal op amp, the potential of the inverting terminal is also zero. So, the  

              electric potential at node 1, is also zero. From the circuit, it is also clear that the current i is  

              the sum of currents of input terminals.

 

 Now, in the case of ideal op amp the current at the inverting and non-inverting terminal are 

zero. So, as per Kirchhoff Current Law, the entire input current passes through the feedback path of resistance Rf. That means, 

From, equation (i) and (ii), we get, 

This indicates that output voltage v0 is weighted sum of numbers of input voltages.

 

6.describe the operation and  chracteristics of the ideal non inverting amplifiers

Then using the formula to calculate the output voltage of a potential divider network, we can calculate the closed-loop voltage gain ( AV ) of the Non-inverting Amplifier as follows:

 

Then the closed loop voltage gain of a Non-inverting Operational Amplifier will be given as:

We can see from the equation above, that the overall closed-loop gain of a non-inverting amplifier will always be greater but never less than one (unity), it is positive in nature and is determined by the ratio of the values of Rƒ and R2.

If the value of the feedback resistor Rƒ is zero, the gain of the amplifier will be exactly equal to one (unity). If resistor R2 is zero the gain will approach infinity, but in practice it will be limited to the operational amplifiers open-loop differential gain, ( AO ).

We can easily convert an inverting operational amplifier configuration into a non-inverting amplifier configuration by simply changing the input connections as shown

 

7.describe the voltage follower.what are the advantages of using this circuit

The voltage follower is the safest and easiest transistor amplifier circuit to build. Its purpose is to provide approximately the same voltage to a load as what is input to the amplifier but at a much greater current. In other words, it has no voltage gain, but it does have current gain. 

the advantage of this circuit is that the op-amp can provide current and power gain; the op-amp draws almost no current from the input.


mohammad akashah bin mohd zamri
mohammad akashah bin mohd zamri
Muhammad Zahin Hafifi Bin Masrizal (1725353) Question 1 1. Internal differential gain Aod is infinite. 2. Differential input voltage (v2-v1) is zero. 3. Effective input resistance is infinite. 4. Output resistance is zero so output voltage is connected directly to dependent voltage source. Question 2 Voltage at node 1 (inverting) = voltage at node 2 (non-inverting ) KCL at node 1:I1 – I2 – Iin = 0(Vi – 0) / R1 = (0 – Vo) / R2Vi / R1 = - Vo / R2Vo/Vi = - R2 /R1Voltage gain, Av = V0/Vi = -R2/R1Input resistance, Ri = Vi/I1 = R1Output resistance, R0 = V0/I2 = R2 Question 3 Virtual Ground is making a node or a connection virtually ground. By the term virtually ground mean, it is not physically connected to ground but voltage at that point/node is 0V. So we refer to it as ground. This concept is used for analysis of operational amplifier circuits. It makes analysis of OP-Amp based circuits very easy. Question 4 The zero output resistance is important because it is easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). It is not so easy to go the other way. We need something that can amplify. An op-amp as a voltage follower is one way to transform a high source impedance into a low source impedance. Question 5 If the input resistances of a summing amplifier are connected to potentiometers, the individual input signals can be mixed together by varying amounts. We can change the gain or add another input without messing with the gains of the other inputs. Just remember that the circuit also inverts the input signals. Not a big deal. If you need the opposite polarity, put an inverting stage before or after the summer. Question 6 Non-inverting amplifier is one in which the output is in phase with respect to the input. The feedback is applied at the inverting input. However, the input is now applied at the non-inverting input. The output is a non-Inverted (in terms of phase) amplified version of input. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs. Question 7 A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used
Muhammad Zahin Hafifi Bin Masrizal (1725353)                                                                                                                                Question 1                                                                                                                                                                                                          1. Internal differential gain Aod is infinite.                                                                                                                                                   2. Differential input voltage (v2-v1) is zero.                                                                                                                                                 3. Effective input resistance is infinite.                                                                                                                                                         4. Output resistance is zero so output voltage is connected directly to dependent voltage source.                                                                                                                                                                                                                                                     Question 2                                                                                                                                                                                                Voltage at node 1 (inverting)  =  voltage at node 2 (non-inverting ) KCL at node 1:I1 – I2 – Iin = 0(Vi – 0) / R1 = (0 – Vo) / R2Vi / R1 = - Vo / R2Vo/Vi =  - R2 /R1Voltage gain, Av = V0/Vi = -R2/R1Input resistance, Ri = Vi/I1 = R1Output resistance, R0 = V0/I2 = R2                                                                                                                                                                                                                                                                                                                                                                                                               Question 3                                                                                                                                                                                                  Virtual Ground is making a node or a connection virtually ground. By the term virtually ground mean, it is not physically connected to ground but voltage at that point/node is 0V. So we refer to it as ground. This concept is used for analysis of operational amplifier circuits. It makes analysis of OP-Amp based circuits very easy.                                                                                                                                                                                                                                                                           Question 4                                                                                                                                                                                                       The zero output resistance is important because it is easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). It is not so easy to go the other way. We need something that can amplify. An op-amp as a voltage follower is one way to transform a high source impedance into a low source impedance.                                                                                                                                                                                                                  Question 5                                                                                                                                                                                                           If the input resistances of a summing amplifier are connected to potentiometers, the individual input signals can be mixed together by varying amounts. We can change the gain or add another input without messing with the gains of the other inputs. Just remember that the circuit also inverts the input signals. Not a big deal. If you need the opposite polarity, put an inverting stage before or after the summer.                                                                                                                                                                                                                                                                                                                                                     Question 6                                                                                                                                                                                                     Non-inverting amplifier is one in which the output is in phase with respect to the input. The feedback is applied at the inverting input. However, the input is now applied at the non-inverting input. The output is a non-Inverted (in terms of phase) amplified version of input. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs.                                                                                                                                                                                                                                                          Question 7                                                                                                                                                                                                           A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used


bob
bob
1)The IC Op-amp comes so close to ideal performance that it is useful to state the characteristics of an ideal amplifier without regard to what is inside the package.
     i)Infinite voltage gain
     ii)Infinite input impedance
     iii)Zero output impedance
     iv)Infinite bandwidth
      v)Zero input offset voltage 

    Implications :
 i) input resistance is infinite, so current flow into either input terminals=0 
 ii) differential input offset voltage is 0.

2) Applying a resistor across the Op Amp to cause an affect called Negative feedback. This effect produces a gain of amplifier in a closed loop. Negative feedback results in the output voltage to have a opposite signal than input voltage characteristics.

3)Virtual Ground is a node of a circuit  that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence. 
 
4)The output impedance of the ideal operational amplifier is assumed to be zero acting as a perfect internal voltage source with no internal resistance so that it can supply as much current as necessary to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load.

5) ideal summing circuit is a circuit that add several signals and combine voltages on inputs into a output voltage. We can change the gain or add another input without messing with the gains of  other inputs. 
 
6) Op-Amp is identified as non-inverting format when the output is in phase with the input signal. In this circuit the signal is applied to the non-inverting input of the op-amp. The signal  of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor    is taken to ground. It has to be applied to the inverting input as it is negative feedback.
 
 7) A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1.
  This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage,      meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. 
Voltage Follower, using an OpAmp, may have a rather precise copying of Vin onto Vout, with ability to handle varying loads while still performing that precise copying.
1)
1)
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Mohamad Haziq Bin Mohamad Faizal (1727001)
Mohamad Haziq Bin Mohamad Faizal (1727001)
Question 1
 The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions. 
Question 2
The characteristics of the ideal inverting amplifier is no current flows into the input terminalsand the differential input voltage is zero.
Question 3
Virtual Ground is a node of a circuit  that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence. 
Question 4 
An ideal constant voltage power supply should have zero output impedance so that changes in the load such as higher load currents do not cause a voltage drop at the output. In addition, the low impedance helps in reducing the noise and interference. When the supply has high impedance, high load current causes a voltage drop across this impedance and lower the output voltage.
Question 5
A summing amplifier is a one kind of circuit which is used to add when the two or more signals need to be combined like in audio mixing applications. The sounds from various musical devices can be changed to an exact voltage level by using transducers, and linked as i/p to a summing amplifier. These different signal sources will be added together by this amplifier, and the added signal is directed to an audio amplifier. Question 6The basic non-inverting amplifier circuit using an op-amp is shown above. In this circuit the signal is applied to the non-inverting input of the amplifier. However the feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It is the value of these two resistors that govern the gain of the operational amplifier circuit. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs. As the input to the op-amp draws no current this means that the current flowing in the resistors R1 and R2 is the same. The voltage at the inverting input is formed from a potential divider consisting of R1 and R2, and as the voltage at both inputs is the same, the voltage at the inverting input must be the same as that at the non-inverting input.
Question 7 
Voltage follower is an op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. 

Question 1
 Question 1
Ideal Op-Amp are as follows:
- infinite input impedance and zero output impedance.
-use dual power supplies 
-have more than one compensation pin.
-the offset voltage due to the 0 V input. 

Implications :
-input resistance is infinite, so no current flow into either input terminals 
-differential input offset voltage is zero

Question 2
To produce a very stable op amp system, a negative feedback has to be created by sending back the signal to the inverting input/amplifier. This is done by using an external feedback resistor hence forces the differential input voltage towards zero. 
Characteristics:
o No current flows into input terminal
o Differential input voltage is zero

Question 3
 Virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). This concept will make almost all calculations becomes simple. It is not electrically connected to the ground since it is virtual. This concept is only valid if negative feedback is applied like in inverting amplifier. 

Question 4
The output impedance of the ideal operational amplifier is assumed to be zero acting as a perfect internal voltage source with no internal resistance so that it can supply as much current as necessary to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load. Real op-amps have output impedances in the 100-20kΩ range.

Question 6
The input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a voltage divider network. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability.
Characteristic:
• output signal is “in-phase” with the input signal.

Question 7
As the input signal is connected directly to the non-inverting input of the amplifier the output signal is not inverted resulting in the output voltage being equal to the input voltage, Vout = Vin. This then makes the voltage follower circuit ideal as a Unity Gain Buffer circuit because of its isolation properties.
Advantages:
• It can be used when impedance matching or circuit isolation is more important than amplification as it maintains the signal voltage.
• to isolated circuits from each other hence separating one filter stage from the other


Mohamad Norfaieqwan bin Kamarudin (1727771)

Mohamad Norfaieqwan Kamarudin (
Mohamad Norfaieqwan Kamarudin (
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Discussion
Discussion
Question 1 

1. Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages. 
- Ideal Op-Amp model is a three terminal circuit element that is modelled as a 
voltage-controlled voltage source. 
- It comes so close to ideal performance that it is useful to state the characteristics of an ideal amplifier without regard to what is inside the package. 
Its characteristics are : 
Infinite voltage gain
Infinite input impedance
Zero output impedance
Infinite bandwidth
Zero input offset voltage (i.e., exactly zero out if zero in).
     The implications of this model are 

• Infinite common-mode rejection 
• Infinite power supply rejection 
• Infinite output voltage range 
• Infinite output current capability 
• Infinite open-loop bandwidth 
• Infinite slew rate 
• Zero output resistance 
• Zero input-bias currents and offset current 
• Zero input-offset voltage 
 
2. Describe the operation and characteristics of the ideal inverting amplifier. 
 
 An ideal inverting-amplifier circuit is built by grounding the positive input of the operational amplifier and connecting resistors R1 and R2, called the feedback network, between the inverting input and the signal source and amplifier output node. 
Characteristics are : 
 No Current Flows into the Input Terminals 
The Differential Input Voltage is Zero as V1 = V2 = 0 (Virtual Earth) 
   
 Operation 
In the amplifier circuit, the inverting-input terminal of the operational amplifier is at ground potential, 0 V, and is referred to as a virtual ground. 
 The ideal Operational amplifier adjusts its output to whatever voltage is necessary to force the differential input voltage to zero.
 Because of the virtual ground at the inverting input, input voltage vi appears directly across resistor R1 and establishes an input current vi/R1. The op amp forces this input current to flow through R2 developing a voltage drop of vi · (R2/R1). Thus vo = −vi (R2/R1) and Av = −(R2/R1). 
3. What is the concept of virtual ground? 
 
Virtual ground is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential.
 In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence. 
 A voltage divider, using two resistors, can be used to create a virtual ground node. If two voltage sources are connected in series with two resistors, it can be shown that the midpoint becomes a virtual ground if  Vout/Vin = -Rf/Rin. 

V out/ V in = − R f /R in 

4. What is the significance of a zero output resistance? 
 
 The voltage may not drop across it and it would not receive the signal. 
 It would draw significant amounts of current into it. Thus, it would be a large load on the circuit. 
 

 5. Describe the operation  and characteristics of the ideal summing amplifier 
 
The summing amplifier is a handy circuit enabling you to add several signals together.
Can change the gain or add another input without messing with the gains of the other inputs. 
 
Operation 
Keep the potential of the negative terminal very close to the positive terminal. In this case, keep the negative terminal close to 0V (virtual ground). 
 The op amp essentially nails one leg of R1, R2 and R3 to a 0V potential. This makes it easy to write the currents in these resistors. 
       I1 = V1 / R1;    I2 = V2 / R2;   I3 = V3 / R3 
·         According to our friend Kirchoff, we get 
        I = I1 + I2 + I3 
·        So the output becomes Vo = -RF x I. 
Vo = - RF ( V1 / R1  +  V2 / R2  +  V3 / R3) 
      = - ( V1 · RF / R1  +  V2 · RF / R2  +  V3 · RF / R3 ) 
·        The gain for each input can be controlled by a single resistor: 
K1 = -RF/R1, 
K2 = -RF/R2 
K3 = -RF/R2. 
     
 
 
6. Describe the operation and characteristics of the ideal non inverting amplifier 
 
 
 The input signal is applied to the positive or (noninverting) input terminal of 
      the operational amplifier, and a portion of the output signal is fed back 
      to the negative input terminal (negative feedback). 
 
 Analysis of the circuit is performed by relating the voltage at V1 to both input voltage Vi and output voltage Vo. 
Operation 
·        Since the voltage across the inputs of the op amp must be zero , input voltage vi appears directly across resistor R1 and establishes a current vi/R1. 
·        This current flows down through R2 developing a scaled replica of vi {i.e., vi · (R2/R1)} across R2. 
·        The output is the sum of the voltages across R1 and R2 yielding vo = vi + vi (R2/R1) and Av = 1 + R2/R1. 

 7. Describe the voltage follower. what are the advantages of using this circuit. 
 

The value of R1 is infinite and that of R2 is zero. 
 
Advantages 
Provides a gain of 1 with infinite input resistance and zero output resistance and therefore provides a tremendous impedance-level transformation while maintaining the level of the signal voltage. 
Does not require any input current, yet can drive any desired load resistance without loss of signal voltage.
To transfer a voltage from one point in the circuit to another point without directly connecting the points together .

-Muhd Zulhelmie Samsuri
-1720589

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Nuranisa Suhada Binti Abd Rahim (1721952)
Nuranisa Suhada Binti Abd Rahim (1721952)
 Answer 1 

The current in or out of either input is negligible .No current flowing in and out of the input terminals of the op-amp (high input impedance of op-amp). If the output is not in saturation, the voltage between the inverting and non-inverting input terminals is zero. 

Answer 2 

In this Inverting Amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. When dealing with operational amplifiers there are two very important rules to remember about inverting amplifiers, these are: “No current flows into the input terminal” and that “V1 always equals V2”. However, in real world op-amp circuits both of these rules are slightly broken. 
This is because the junction of the input and feedback signal ( X ) is at the same potential as the positive ( + ) input which is at zero volts or ground then, the junction is a “Virtual Earth”. Because of this virtual earth node the input resistance of the amplifier is equal to the value of the input resistor, Rin and the closed loop gain of the inverting amplifier can be set by the ratio of the two external resistors. 
 
Answer 3 

A virtual ground, sometimes known as  a virtual short. In this case, it would be referred to as a virtual ground. At least for calculation of current, we can consider that there is actually a ground between here and … If it was a real ground, we would have no output because simply the signal would come in and go straight to ground, it would never get to the amp. This is a virtual ground but because for calculation purposes and analyzation, it does look like a ground. 
If we took this voltage in and we divided it by the resistance here, we would get a current and that current is not going to flow into the op amp because it has infinite resistance. That current will be felt through this resistance up here. Sometimes this is referred to as RF or feedback resistor. The value that flows through that current will develop a voltage and that will result in our output. 
We'll look at negative feedback in more detail later, but what we're going to find is that we can get a very predictable gain based upon the sizes of these two components. 
The same concept will result down here. We call this a virtual ground. Oftentimes, in this case, it would be called a virtual short because if you calculate the value of this voltage across this component, then we can do basically the same kind of calculation. 

Answer 4 

The output of an op amp comes from a source internal to it that has an associated series resistance. Here we see the input and we see an associated series resistance that's going to become our output resistance. 
The effective resistance is called the output resistance of an op amp. We looked at that back in the transistor section. 
Negative feedback lowers the effective output resistance. It is low enough that for practical purposes, we will consider it to be zero. 

 Answer 5 

The output voltage of a summing amplifier is proportional to the negative of the algebraic sum of its input voltages. Hence, the name summing amplifier. A summing amplifier is an inverted OP-Amp that can accept two or more inputs. 
 
Three voltages V1, V2 and V3 are applied to the inputs and produce currents I1, I2 and I3. 
The inverting input of the OP-Amp is at virtual ground (0 V) and there is no current to the input. 

So, the three input currents I1, I2 and I3 combine at the summing point A and form the total current If which goes through Rf as shown in figure above. 
 

 
When all the three inputs are applied, the output voltage is  

Thus the output voltage is proportional to the algebraic sum of the input voltages. 

If Rf =R1=R2=R3=R, then, we have 
 
Thus, when the gain of summing amplifier is unity, the output voltage is the algebraic sum of the input voltages. 

Answer 6 

 In the non-inverting, we're going to send in this input signal and since it's the non-inverting, the output will be the same phase as the input. 
Then we have a portion of that is fed back to the inverting input and so, notice, that is coming in like this. It's in the same phase. Recall that an op amp amplifies the difference. If we had the same phase of input on both inputs, then, again, this will tend to attenuate the signal. This idea of negative feedback is that the feedback opposes the original input signal. 
Again, this will attenuate the total gain from what we would have in AOL, but, again, it will make for an ACL, which is a closed-loop gain, and it will be an extremely predictable amount of gain. 
Since the op amp ideally has infinite input resistance, no current flows into the input. Remember, we've mentioned that several times, that this effectively has infinite input impedance. What we're going to say is that we're going to send in an input voltage and it will go across this resistance. 

Answer 7 

There are two important pros of the voltage follower which are the required unity gain is much more precise if compared with an emitter follower and the output resistance is much more smaller. 



 




NUR HUSNINA BINTI MUHAMAD ZURAIDI (1723394)
NUR HUSNINA BINTI MUHAMAD ZURAIDI (1723394)
 
Question 1
Op Amp is an integrated circuit that have well defined operating characteristics. The characteristics for ideal op amp are :
Infinite input impedance
Zero output impedance
Infinite voltage gain
Gain is independent of input frequency
Infinite bandwidth
Zero input offset voltage
Output can swing positive or negative to the same voltages as the supply rails 
 
The implications of this ideal model in terms of input current and voltages :
Input resistance of ideal Op Amp is infinite, so the input current will be zero which is no current flows.
Voltage gain is independent to output current
 
Question 2
The operation and characteristics of ideal inverting amplifier
The input signal is applied in the inverting input terminal, so the output being reversed 
Rf (feedback resistor) connected between output and inverting input terminals
The junction is virtual earth because the feedback signal is at the same potential as positive input which is zero volts
Virtual earth node the input resistance of the amplifier = the value of Rin
Closed loop gain of the inverting amplifier = the ratio of two internal resistor
The output is the inverse or 180° out of phase with the input
Vout = -(Rf/Rin) x Vin
The characteristics :
No current flows into the input terminals
The difference of input voltage is zero 

Question 3
Concept of virtual ground
The voltage at that particular node is almost equal to ground voltage (0V)
A concept that made for easy explanation and calculation purposes
Not electrically connected to ground
Voltage is approximately zero
Not able to sink infinite current
The concept is useful to analyse op amp when negative feedback is employed 

Question 4
The significance of a zero output resistance
The measure of the opposition to current flow
Output resistance comes from internal source that has associated series resistance
The output resistance of the op amp is the effective resistance
The negative feedback will lower the effective output resistance, and considered as zero for practical purposes 
 
Question 5
The operation and characteristics of the ideal summing amplifier
Operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage
The output voltage becomes proportional to the sum of the input voltages
- Vout = (Rf/Rin) (V1 + V2 + V3 ……..etc)
Input signals are effectively isolated from each other by the virtual earth node at the inverting input of the op amp
When the summing point is connected to the inverting input of the op amp, the circuit will produce the negative sum of input voltages and vice versa 
 
Question 6
The operation and characteristics of the ideal non inverting amplifier
The output is in the same sense or in phase with the input
Basic circuit :
The feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to the ground
The gain of the amplifier is exceedingly high
When the input draws no current, so the current flows in R1 and R2 is the same
Voltage at inverting input formed from a potential divider consist of R1 and R2, the voltage at both input is same, so voltage at inverting input must be the same as the non inverting input
Vin = Vout x R1 / (R1 + R2) 
 
Question 7
The voltage follower and the advantages of the circuit
Called as unity-gain amplifier, buffer amplifier or isolation amplifier
Op-amp has a voltage gain of 1
Does not provide any amplification to the signal
Output voltage = input voltage
Act as a buffer, provide no amplification to the signal
Draws a little current from power source
Not disturbing the original circuit
Give same voltage signal as output
Isolate the circuit so the power of the circuit disturbed very little
Importance in voltage divider circuits
Allow designer to supply efficient voltage to load 
Question 1
 Question 1
The characteristic of ideal op amp:
- Infinite voltage gain
-Infinite input impedance (nearly to very large value so it considered as infinte)
-Zero output impedance (the value close to zero)
-Infinite bandwidth
-Zero input offset voltage
Based on these characteristics, we can say that current cannot flow in or out from input terminal. Plus, the output will make the voltage difference between input become zero in the close loop.

Question 2
   
In this Inverting Amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. When dealing with operational amplifiers there are two important rules to remember about inverting amplifiers: 
-No current flows into the input terminal 
-V1 always equals V2
(But these two rules are invalid in real world op amp circuit)

This is because the junction of the input and feedback signal ( X ) is at the same potential as the positive ( + ) input which is at zero volts or ground then, the junction is a “Virtual Earth”. Because of this virtual earth node the input resistance of the amplifier is equal to the value of the input resistor, Rin and the closed loop gain of the inverting amplifier can be set by the ratio of the two external resistors. 

Question 3
By the term virtual ground, it does not mean it connected to the ground, but the value is about to similar with zero value which is considered as ground.
   
Consider an Inverting Op-amp Configuration with negative feedback. Referring to Ideal Op-Amp parameters, Input Impedance is ∞. So ideally no current flows through Op-amp.

As there is no current flowing through Op-amp, Current (Ia) flowing through node Va will be ‘0’. And by Ohm’s Law we could conclude that Va=0. V= I X R, as I is 0 perhaps V will also be ‘0’. 

Question 4
 We want the op-amp to be able to drive its output pin to the required voltage, irrespective of how much load there is on that output. Again, we want minimum “corruption” of the signal, so the lower the output resistance, the better the op-amp is able to “override” the influence of any surrounding circuitry by sinking or sourcing as much current as required.  In reality, no op-amp is “ideal”, but they come close enough that they can be assumed to be “ideal” in calculations for most practical purposes. 

Question 5
 The summing amplifier is a handy circuit enabling us to add several signals together. Its easy to understand that the main operation of op amp is to keep the potential of the negative terminal very close to the positive terminal.  In this case, keep the negative terminal close to 0V (virtual ground). The op amp essentially nails one leg of resistors in the circuit to a 0V potential. 

Question 6
 As for the non-inverting amplifier, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout.

Question 7
 Voltage follower is an op amp circuit whose output voltage straight away follows the input voltage. That is output voltage is equivalent to the input voltage. Op-amp circuit does not provide any amplification. Thus, voltage gain is equal to 1. They are similar to discrete emitter follower. The other names of voltage follower are Isolation Amplifier, Buffer Amplifier, and Unity-Gain Amplifier. The voltage follower provides no attenuation or no amplification but only buffering. This circuit has an advantageous characteristic of very high input impedance.
This high input impedance of voltage follower is the reason of it being used in several circuits. The voltage follower gives an efficient isolation of output from the input signal. 

The advantage of Voltage Follower :
Provides power gain and current gain
Low output impedance to the circuit which uses the output of the voltage follower
The Op-amp takes zero current from the input.
Loading effects can be avoided

Raja Amirul Hisham bin Raja Zafri (1721423)


Q1
Q1
1) Infinite voltage gain.
2) Have infintely high input  impedance. Ensure that the op amp causes no loading in the circuit. The lower the input impedance, the more current that an op amp will draw. The higher the impedance, the lower the current that an op will draw.
3) Have zero output impedance. We want Op amp to have zero voltage so that the maximum voltage will be transferred to the output load.  In order for the voltage to drop across the output load, that load must be of greater impedance than the output of the op amp. 
4) The gain that the op amp produces will be independent of frequency. This means that regardless of the frequency of the input signal going into the op amp.
5)  If no voltage is applied to the inverting and nonnverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins. 

Q2
1) No Current Flows into the Input Terminals.
2) The Differential Input Voltage is Zero as V1 = V2 = 0 

Q3
1)   A voltage divider,  using two resistors, can be used to create a virtual ground node.  If two voltage sources are connected in series with two resistors, it can be shown that the midpoint becomes a virtual ground 
2)
Gain = Vo/Vin
As gain is infinite, Vin = 0
Vin = V2 – V1
In the above circuit V1 is connected to ground, so V1 = 0. Thus V2 also will be at ground potential. 
3)  Voltage is approximately Zero .
4)  Not able to sink infinite current .
5)   Not electrically connected to Ground .

Q4
1) To transfer all output voltage to the load.
2) As the voltage drops, it will amplify the signal. 

Q5
1)  
Summing Amplifier Circuit

The summing amplifier circuit is shown below. In the circuit below Va, Vb and Vc are input signals. These input signals are given to the inverting terminal of the operational amplifier using input resistors like Ra, Rb and Rc. In the above manner, the number of input signals can be given to the inverting i/p. Here, Rf is feedback resistor and RL is the load resistor. Noninverting terminal of the operational amplifier is given to the ground terminal using Rm resistor. By applying KCL at node V2 we can get the following equation. 

If + Ib= Ia + Ib + Ic

The input resistance of an ideal operational amplifier is near to infinity, so we can neglect V2 and Ib

If= la + lb + lc

The first equation can be written as

(V2-V0)/Rf = Va/Ra + Vb/Rb + Vc/ Rc

By neglecting V2 we can get the following equation

-V0/Rf = Va/Ra + Vb/Rb + Vc/ Rc

V0 = -Rf (Va/Ra + Vb/Rb + Vc/ Rc)

V0 = -(Rf/Ra)/Va + (Rf/Rb)Vb + (Rf/ Rc) Vc

If the values of resistors Ra, Rb and Rc are same then the above equation can be written as

Vo= ( Va + Vb + Vc) X –( Rf/R)

If the values of R and Rf are similar, then the equation becomes
V0 = -(Va + Vb + Vc)

Q6
1)In this configuration, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit we saw in the last tutorial whose output gain is negative in value. The result of this is that the output signal is “in-phase” with the input signal.

Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout as shown below.





Q7
1)  
A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1.

This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. 

2)  
Voltage Followers Draw Very Little Current

When a circuit has a very high input impedance, very little current is drawn from the circuit. If you know ohm's law, you know that current, I=V/R. Thus, the greater the resistance, the less current is drawn from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load.
Let's look at both illustrations below:
The below circuit is a circuit in which a power source feeds a low-impedance load. 




In this circuit above, the load demands and draws a huge amount of current, because the load is low impedance. According to ohm's law, again, current, I=V/R. If a load has very low resistance, it draws huge amounts of current. This causes huge amounts of power to be drawn from the power source and, because of this, causes high disturbances and use of the power source powering the load.
Now let's look at the circuit below, connected to an op-amp voltage follower:




 
This circuit above now draws very little current from the power source above. Because the op amp has such high impedance, it draws very little current. And because an op amp that has no feedback resistors gives the same output, the circuit outputs the same signal that is fed in.

This is one of the reasons voltage followers are used. They draw very little current, not disturbing the original circuit, and give the same voltage signal as output. They act as isolation buffers, isolating a circuit so that the power of the circuit is disturbed very little. 


MUHAMMAD FARIS BIN NOR APANDI (1726779
Mazarina abu othman (1725268)
Mazarina abu othman (1725268)
Answer 1 :

The ideal op amp is a three terminal circuit element that is modeled as a voltage-controlled voltage source. That is, its output voltage is a gain multiplied by its input voltage. The input voltage is the difference voltage between the two input terminals. The output voltage is measured with respect to the circuit ground node. 
Then, In an ideal op amp, if no voltage is applied to the inverting and noninverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins. The current into terminal 1 and signal into terminal 2 are both zero. The terminal characteristics of the ideal op amp satisfy four conditions. These are as follows:
1. The current in each input lead is zero.
2. The output voltage is independent of the output current.
3. The voltage gain A is independent of frequency.
4. The voltage gain A is very large, approaching infinity in the limit

Answer 2:
Inverting amplifiers are used as summing amplifiers, which sums the voltage present on multiple inputs and combines them into a single output voltage. The below figure, illustrates the amplifier's inverting configuration. 
There are an operation amplifier and two resistors R1 and R2 inside of the inverting configuration. The second resistor, R2 is connected from terminal 3 (output terminal), back to terminal 1, which is the inverting (-) input terminal. As R2 is connected in this manner, we can apply negative feedback, which is the process of "feeding back" a small portion of the output signal back into the input terminal. However, in order to make the feedback negative, the output signal must be fed into the inverting terminal of the operation amplifier. Also, if R2 was connected between the output terminal 3 and the input terminal 2 (noninverting input), there would be positive feedback. Now the output signal is fed back into the noninverting (+) input, creating a positive feedback into the operational amplifier. If you look at the diagram closely, R2 also closed the loop surrounding the operational amp. In addition to R2 in this configuration, terminal 2 has been grounded and connected to the resistor R1 in between terminal 1 and the input signal source of voltage v1. Between terminal 3 and the ground is the point from which we will take the output since there is an impedance level that is ideally zero. Due to this, voltage v0 does not depend on the impedance value of the current that is supplied to the load impedance that is connected between the ground and terminal 3.

Answer 3 :
Virtual Ground Concept, As the name suggests Virtual Ground is making a node or a connection virtually ground. By the term virtually ground means, its not physically connected to Ground but voltage at that point/node is ‘0V’ so we refer to it as Ground. This concept is used for Analysis of Operational Amplifier Circuits. It makes analysis of OP-Amp based circuits very easy.

Answer 4 :
The output of an op amp comes from a source internal to it that has an associated series resistance. Here we see the input and we see an associated series resistance that's going to become our output resistance.
The effective resistance is called the output resistance of an op amp. We looked at that back in the transistor section.
Negative feedback lowers the effective output resistance. It is low enough that for practical purposes, we will consider it to be zero.

Answer 5 :





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QUESTION 1
 QUESTION 1
Ideal Op Amp characteristic are:
> It has Infinite voltage gain
> It also has Infinite Input impedance and zero output impedance
> Its gain is independent of the input
> Zero input offset voltage

QUESTION 2
Operation
> Applying a resistor across the Op Amp to cause an affect called Negative feedback.
> This effect produces a gain of amplifier in a closed loop
> Negative feedback results in the output voltage to have a opposite signal than input voltage
Characteristics
> No current flow into the input terminal
> V1=V2=0

QUESTION 3
> Virtual ground is not physically connected to the ground
> The potential difference at inverting and non-inverting terminal is always the same
> It is because of high input impedance

QUESTION 4
> To transfer all output voltage to the load.
> As the voltage drops, it will amplify the signal.

QUESTION 5
> A circuit that add several signals
> Combine voltages on inputs into a output voltage
> Output of the amp is the function of the summation of the input voltages
> Vout proportional to the sum of input voltages

QUESTION 6
> Output is in phase with the input signal
> Inverting input is connected with ground
> Feedback resistor connected between output and input terminal
> Its gain depends on passive component for stability

QUESTION 7
> Output voltage follows directly with the input voltage
> Output voltage and input voltage are equal
> A circuit which gain voltage is 1
> Op amp does not provide any amplification to the signal
> Circuit will have a very high impedance; less current off the circuit

MUHAMMAD SHAHRUL AFIQ BIN MOHAMAD RAFI ( 1728793 )
SITI NURHIDAYAH BT SULAIMAN (1720600)
SITI NURHIDAYAH BT SULAIMAN (1720600)
 
Q1 

An ideal op amp have the following characteristics : 

-Ideal op amps will have infinite voltage gain.  A voltage is input into the op amp and as output, it produces the voltage amplified. An ideal op amp will produce mega-gain, practically, it will be able to produce infinite gain. It will amplify the signal infinite times over so that we can have as much gain as we'd ever need. 

-Infinitely high input impedance.  This will ensure that the op amp causes no loading in the circuit. The lower the input impedance, the more current that an op amp will draw. The higher the impedance, the lower the current that an op will draw. We want high input impedance so that the op amp doesn't disturb the original circuit by pulling current from it. To do this, we need infinitely high input impedance. 

-Zero output impedance.  When an op amp produces its output signal, we want the op amp to have zero voltage so that the maximum voltage will be transferred to the output load. 

-Its gain is independent of input frequency , regardless of the frequency of the input signal going into the op amp, the gain that is produced will be constant and good across all frequencies. 

 -It has zero voltage offset,  if no voltage is applied to the inverting and noninverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins. 

Q2 
   
There are an operation amplifier and two resistors R1 and R2 inside of the inverting configuration. The second resistor, R2 is connected from terminal 3 (output terminal), back to terminal 1, which is the inverting (-) input terminal. As R2 is connected in this manner, we can apply negative feedback. In addition to R2 in this configuration, terminal 2 has been grounded and connected to the resistor R1 in between terminal 1 and the input signal source of voltage v1. Between terminal 3 and the ground is the point from which we will take the output since there is an impedance level that is ideally zero. Due to this, voltage v0 does not depend on the impedance value of the current that is supplied to the load impedance that is connected between the ground and terminal 3. 

Q3 

In op amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground. An active virtual ground circuit is sometimes called a rail splitter. Such a circuit uses an op-amp or some other circuit element that has gain. Since an operational amplifier has very high open-loop gain, the potential difference between its inputs tend to zero when a feedback network is implemented. This means that the output supplies the inverting input (via the feedback network) with enough voltage to reduce the potential difference between the inputs to microvolts. Thus, as far as the amplifier is working in its linear region (output not saturated, frequencies inside the range of the opamp), the voltage at the output terminal remains constant with respect to the real ground, and independent from the loads to which it may be connected. This property characterize a "virtual ground". 

Q4 

The output resistance of an electrical network is the measure of the opposition to current flow. An ideal op amp will have zero output resistance. When an op amp produces its output signal, we want the op amp to have zero voltage so that the maximum voltage will be transferred to the output load. Voltage is divided in a circuit according to the amount of impedance present in a circuit. Voltage drops across a component of higher impedance. In order for the voltage to drop across the output load, that load must be of greater impedance than the output of the op amp. 

Q5 
 
It is called a summing amplifier, because two signals are summed in one of the amplifier inputs.  In this case, V1 and V2 are summed in the non-inverting input. The summing of V1 and V2 is not direct.  Resistors R1 and R2 make a weighted sum and this is what makes this amplifier very useful. 

Q6 

 
In this configuration, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value. The result of this is that the output signal is “in-phase” with the input signal. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout as shown below. 

 

Q7 

A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is an op-amp circuit which has a voltage gain of 1. 

This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. 

An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used. 




Question 1
Question 1



DISCUSSION
DISCUSSION 
(NUR ANIS SYAKIRAH MOHD RUZI - 1729186)
QUESTION 1:
The ideal Op Amp (Operational Amplifier) is a model that has three circuit element. It is a voltage controlled voltage source with very high gain. It is modeled with differential input terminals and has a single output terminal. The characteristics of an ideal amplifier are:
Infinite voltage gain
Infinite input impedance
Zero output impedance
Infinite bandwidth
Zero input offset voltage 
In the terms of input current the input resistance of this ideal Op Amp is infinite, which can make the current in each input to be zero. So, no current flows. In terms of voltage, the voltage gain is independent of the output current. The input voltage is the difference voltage between the two input terminals.The output voltage is measured with respect to the circuit ground node. The output will attempt to make the voltage difference between the two input terminals to be zero if it is finite.

QUESTION 2:
An operational amplifier can be in the arrangement of inverting and non-inverting amplifier. It will operate depending on the terminal at which the signal is applied, which is the fundamental negative feedback configuration . Inverting amplifier arrangement is when the input signal, V1 is applied to the inverting terminal as shown below: It is called an inverting amplifier because its voltage gain is negative. This means that if the input voltage is increasing or going positive, the output voltage will be decreasing or going negative, and vice versa. The operational amplifier is connected with feedback to produce a closed loop operation. At the inverting input terminal, the voltage for both of the terminal is the same and the gain, A is approaching ideally equivalent toward infinity in both input terminal. Since the operation amplifier has an ideal infinite input impedance now, this means that no current flows into the two input terminals and instead it will flow through R2. So, the differential input voltage is zero as V1 = V2 = 0 (Virtual Earth). 
 
QUESTION 3
Virtual ground is refer to the virtual and not the real ground. For some reason we can consider it as equivalent to the real ground. The term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). But it is not physically connected to ground.  Virtual ground concept is very useful in analysis of an operational amplifier when negative feedback occur.  It can made things easy to explain and easy to make calculation. Consider an inverting op amp configuration with negative feedback. Referring to the ideal op amp, the input impedance is infinity. So, ideally no current flows through the op amp. As there is no current flowing through op amp, the current flowing through V1 will be zero. By Ohm’s Law we could conclude that Va=0. V= I X R, as I is zero and V will also be zero. 
 
QUESTION 4
The output resistance is the measure of the opposition to current flow. It is the ratio of change in output voltage to change in load current. An ideal constant voltage power supply should have zero output resistance so that changes in the load such as higher load currents do not cause a voltage drop at the output. The low resistance helps in reducing the noise and interference. When the supply has high impedance, high load current causes a voltage drop across this resistance and lower the output voltage. If we want all of the input current to be fully 'absorbed' by the amplifier, then ideally we need “0” input resistance in the input circuit. Thus, the input current would flow easily through the input circuit if it is in the lowest resistance. 
 
QUESTION 5
The summing amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. It is used to add two signal voltages into a single voltage. It is one of variation of the inverting amplifier. In inverting summer, there is only one voltage signal applied to the inverting input.  the input voltages are given to the inverting terminal and non-inverting terminal is grounded, but the difference in Inverting adder circuit is it has multiple inputs at its inverting terminal.  If we connect more input terminals in parallel to the existing input terminals, we  will be end up with another op am circuit which is summing amplifier. Or if we connect more resistors to the input terminal, each input value is equal to the input of the resistor. So,  the input of the resistor can also be considered as summing amplifier. The amplifier is add the signals directly or scale them to fit some prearranged combination rule. 
 
QUESTION 6
Non-inverting amplifier arrangement is when the input signal, V1 is applied to the non-inverting terminal as shown below:  The voltage gain of non-inverting amplifier is at positive input terminal. The feedback applied at the inverting input before is now applied at the non-inverting input. The input voltage signal, V1 is a applied directly to the non-inverting (+) input terminal, which means that the output gain of the amplifier will become positive in value.The voltage gain is always greater than one. This is in contrast with the inverting amplifier circuit, whose output gain will be negative in value. The result of output signal is “in-phase” with the input signal.  A non-inverting amplifier amplifies an input signal without inverting the signal. It also not changing the polarity of the output signal. Meaning that, if the input signal is positive, the output signal is positive.  Next, the voltage at both input is the same. If the output of the circuit remains within the supply of the amplifier, then the output voltage divided by the gain which means that there is virtually no difference between the two inputs. 

QUESTION 7
 A voltage follower also known as unity-gain amplifier or buffer amplifier is a op amp circuit which has a voltage gain of 1. The op amp acts as a buffer which does not provide any amplification to the signal. It is called a voltage follower because the output voltage directly follows the input voltage which means that the output voltage is the same as the input voltage. If 10V goes into the op amp as the input, then 10V will come out as the output. When a circuit has a very high input impedance, the current is dropped in the circuit. Referring to the Ohm's law, I=V/R where the greater the resistance, the less current is dropped from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load. It will not disturb the original circuit, and give the same voltage signal as output. It only draw very little power from the signal source, avoiding "loading" effects.  If a circuit has a plenty of voltage but little current, then by adding a voltage follower it will increase the current that can be supplied. The voltage follower does not amplify the voltage but it will result in the higher output current than before. 

Muhamad Syafiq (1626745
Muhamad Syafiq (1626745

1. The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions 
 An ideal op-amp is usually considered to have the following characteristics: Infinite open-loop gain G = vout / v. Infinite input impedance Rin, and so zero input current. Zero input offset voltage 

2. There are two inportant characteristic of ideal inverted amplifier which is
 1-No current flows into the input terminals
 2-The differential input voltage is zero as V1 = V2 = 0 (Virtual Earth) 

3.Virtual ground in a Op-amp is a phenomenon in which one of the input terminals will have zero terminal voltage although that terminal is not connected to ground terminal

4. In real life there is no such things as 'ideal' Op-amp. This significance of a zero output resistance plays a big role to get approximately for an Op-amp to ideal. For example you want the op-amp to be able to drive its output pin to the required voltage,  so the lower the output resistance, the better the op-amp is able to “override” the influence of any surrounding circuitry by sinking or sourcing as much (or little) current as required. 

5. The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.    
In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V1, V2, V3, etc. Then we can modify the original equation for the inverting amplifier to take account of these new inputs thus:

 
6.  
 In this circuit the signal is applied to the non-inverting input of the amplifier. However the feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It is the value of these two resistors that govern the gain of the operational amplifier circuit. 

 The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs. 

7. Voltage Follower- 
   If we made the feedback resistor, Rƒ equal to zero, (Rƒ = 0), and resistor R2 equal to infinity, (R2 = ∞), then the circuit would have a fixed gain of “1” as all the output voltage would be present on the inverting input terminal (negative feedback). This would then produce a special type of the non-inverting amplifier circuit called a Voltage Follower or also called a “unity gain buffer”.
As the input signal is connected directly to the non-inverting input of the amplifier the output signal is not inverted resulting in the output voltage being equal to the input voltage, Vout = Vin. This then makes the voltage follower circuit ideal as a Unity Gain Buffer circuit because of its isolation properties.


DISCUSSION
DISCUSSION
  
NUR WAHIDAH BINTI ZULKIFLI
172394 

(Question 1)
 Operational amplifier or op-amp is a high gain voltage amplifier. An op-amp has a differential input with a single ended output. An amplifier is considered as an ideal op-amp if it has these characteristic. The first characteristic to be considered as ideal op-amp is the open loop voltage gain (G), which is the gain without positive or negative feedback, must be infinite. Next, the input impedance is infinite. In order to get infinite input impedance, input current must be zero. After that, it has zero output impedance. It is because ideal op-amp need to act as a perfect internal voltage source without any internal resistance. So, from these characteristic, we can say that in ideal op-amp, current cannot flow in or flow out of the input terminals. Besides, the output will make the voltage difference between the input zero in a close loop.
 
 (Question 2)
     Operational amplifier can be in inverting amplifier circuit or non-inverting amplifier circuit. The difference between both circuits is where the op-amp connected. So, in inverting amplifier, op-amp is connected to the feedback. When op-amp is connected to the feedback, it will invert input to receives feedback from the output of the amplifier. It then will produce closed loop operation. The closed loop operation can be set by the ratio of two external resistor. During the inverting operational amplifier,  there will be no current flow in or out of the input terminal. Therefore, when there is no current flow, the differential input will be zero. This is because at point x or "virtual earth", the input and the feedback signal is at the same potential with positive input which is at zero volts. Hence, V1 will be equal to V2. The virtual earth then will caused the input resistance of the amplifier equal to the input value of resistor.
 
 (Question 3)
 Virtual ground or virtual earth is a node of a circuit that maintained at a steady reference potential which also called as potential at ground terminal. It is maintained without directly connected to the reference potential. For some cases, it can be considered equal to the ground which referred to the reference node. However, unlike the real ground terminal, there is possibility that the current will be restricted. It is because it is not physically connected to the ground. As it is indicates to its name, it is virtual, not real ground. This concept is used in analysis the op-amp circuit. In op-amp circuit, the virtual ground usually refers to the small signal analysis. In order to practice this concept, first, the inverting op-amp circuit need to be considered with a negative feedback. Then, by referring to the ideal op-amp parameters, the input impedance will be infinite. Hence, there will be no current flow in or out of op-amp through node Va. When there is no current, we can conclude that Ia is equal to 0. Therefore, Va also will be 0 as according to the Ohm's Law, V = IR and right now I is 0, hence V will also be 0.
 
 (Question 4)
 Zero output resistance is important when the op-amp want to drive its output pin to required voltage. It does not depend on how much load in  the output. In order to get a minimum disturbance of the signal, therefore, we need to lower the output resistance. It is to ensure that we get better op-amp in order to able to override the influence of any surrounding circuitry by sinking or sourcing as much current as required. To get an ideal op-amp, the circuit need to have zero output resistance. It implies that the output voltage is independent of the load connected to the output.
 
 (Question 5)
 Summing amplifier is another type of inverting amplifier. As indicates by its name, it enable us to add several signal together. In inverting amplifier, there is only a single voltage signal applied to it. However, it can be easily modified by combining the voltage present on several inputs in parallel so it will make a single output voltage. If we add more input resistor to the input, each of it will have the same value with the previous input resistor and will cause another summing amplifier circuit. In summing amplifier, the value of output voltage is the total of voltages input, Vout = V1+V2+V3+....From that equation, we can modified it by referring to the Ohm's Law or by applying KCL or KVL in order to find another input. 
 
 (Question 6)
  The other types of operational amplifier is non-inverted amplifier. In non-inverted amplifier, the input of amplifier is connected to the ground. Before, in inverted amplifier, the feedback is applied at inverting input, but now, the input is applied at the non-inverting input. The output is in phase with the output. While the gain of the amplifier is exceedingly high, the voltage for both inputs is the same. The output voltage is divide by the gain as the output of the circuit remain the same within the amplifier. Hence, there is no difference between the two inputs. Previously, in inverted amplifier, there is no current flow and both V1 and V2 is equal is because of the junction that caused the input and V1 at same potential. Therefore, the junction which is the virtual earth act as summing point and because of that, Rf and R2 form a potential divider network across the non-inverted amplifier. The voltage gain also can determined by the ratios of R2 and Rf. The closed loop gain will be greater but less than one but if the value of Rf is zero than the gain will be equal to one.
 
 (Question 7)
 Voltage follower or also known as unity gain buffer is a type of non-inverted amplifier circuit which has a fixed voltage gain of 1 and do not amplify the incoming signal. It is called voltage follower because the output voltage directly followed the input voltage. The voltage amplifier can helped to boost available current from the circuit without increasing the voltage at the same time. The advantage of using voltage follower is it can helped to draw a very little current. An op-amp circuit has a high input impedance and  to balanced the state, it has a low output impedance. By using voltage follower, it enabled the transfer of voltage from a first circuit with a high input impedance to the second circuit with low output impedance while maintain the voltage level. It can helped preserved the voltage signal and prevents the second circuit from loading the first circuit by drawing very little power from the circuit. It is very useful at first stage.Besides, the voltage follower act as isolation buffer by isolating a circuit so that there is only a very little power of circuit is disturbed. Therefore, voltage follower can be add in the circuit when there is a circuit that capable in providing plenty of voltage but little current as it will increase the current that can be supplied. It will not change or amplify the voltage but it can increase the output current higher than the original circuit.


 QUESTION
  
QUESTION 1 

An ideal design of op amp model has two input terminals, an output terminal, two power supply connections, and one or more compensation terminal. These characteristics made the model ideal as an operational amplifier. 
1) Two input terminal- Referring to negative and positive terminal 
2) An output terminal- Op amps are considered has a single-ended output. However, it may have inverted and non-inverted output. Most of the op amps only use the non-inverted output. 
3) Two power supplies connections- There's a positive and a negative supply associated with them. 
4) One or more one compensation pin- These pins are used to fine-tune the behaviour of the op amp. With 0 V on the input pins, some positive or negative output voltage will be produced. This is called the offset voltage. The typical voltage gain is 100,000. If the tiniest voltage on the inputs can cause a rather large output, these pins are required to null out this offset voltage. 
5) Infinite input impedance- An ideal op-amp shouldn't be drawing any current for the inputs which means the current into terminal 1 and signal into terminal 2 are both zero. This is to say that the input impedance of an ideal op-amp is supposed to be infinite. 
6) Zero output impedance
7) Infinite open loop gain, G = Vout/Vin 
8) Zero input offset voltage 
9) Infinite bandwith with zero phase shift and infinite slew rate. 
These characteristics lead to the golden rules for op-amps. They allow you to logically deduce the operation of any op-amp circuit. The rules states that the output attempts to do whatever is necessary to make the voltage difference between the inputs zero and the inputs draw no current.        

 QUESTION 2  The Inverting Operational Amplifier configuration 
Operation 

·         We connect suitable resistor across the amplifier from the output terminal back to the inverting input terminal to both reduce and control the overall gain of the amplifier. 
·         This then produces and effect known commonly as Negative Feedback, and thus produces a very stable Operational Amplifier based system. 
·         This feedback connection between the output and the inverting input terminal forces the differential input voltage towards zero. This effect produces a closed loop circuit to the amplifier resulting in the gain of the amplifier 
·         Then a closed-loop inverting amplifier uses negative feedback to accurately control the overall gain of the amplifier, but at a cost in the reduction of the amplifiers gain. This negative feedback results in the inverting input terminal having a different signal on it than the actual input voltage as it will be the sum of the input voltage plus the negative feedback voltage giving it the label or term of a Summing Point. 
Characteristics 

·         When dealing with operational amplifiers there are two very important rules to remember about inverting amplifiers, these are: “No current flows into the input terminal” and that “V1 always equals V2”. 

QUESTION 3 
In electronics, a virtual ground (or virtual earth) is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence. 

QUESTION 4 
Op amps have zero output impedance because of the concept of a voltage divider, which is how voltage is divided in a circuit depending on the amount of impedance present in given parts of a circuit. Once the voltage is dropped across the op amp and it does its task of amplifying the signal, the signal should get dropped across the device that the op amp should feed. For example, say we have a microphone circuit. The signals spoken into the microphone need amplification from an op amp so that they can reach a level that can drive speakers. When the signals are amplified now, they are to be dropped across the speakers. Thus, the speakers must be of greater impedance than the output of the op amp, so that the voltage signals will drop across the speakers. Thus, the op amp needs a very low output impedance, so that the amplified voltage signal drops across the speakers and not the op amp. 


QUESTION 5 
The Summing Amplifier ConfigurationOperations 

·         The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.  in the inverting operational amplifier that the inverting amplifier has a single input voltage, (Vin) applied to the inverting input terminal. 
·         If we add more input resistors to the input, each equal in value to the original input resistor, (Rin) we end up with another operational amplifier circuit called a Summing Amplifier, “summing inverter” or even a “voltage adder” circuit as shown. 

Characteristics 
·         The Summing Amplifier is a very flexible circuit indeed, enabling us to effectively “Add” or “Sum” (hence its name) together several individual input signals. If the inputs resistors, R1, R2, R3 etc, are all equal a “unity gain inverting adder” will be made. However, if the input resistors are of different values a “scaling summing amplifier” is produced which will output a weighted sum of the input signals. 

QUESTION 6 
 Non-inverting Operational Amplifier design.  
Characteristics 
·         For an ideal op-amp “No current flows into the input terminal” of the amplifier and that “V1 always equals V2”. This was because the junction of the input and feedback signal ( V1 ) are at the same potential. 
·         In other words the junction is a “virtual earth” summing point. Because of this virtual earth node the resistors, Rƒ and R2 form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of R2 and Rƒ 

Operations 
Then using the formula to calculate the output voltage of a potential divider network, we can calculate the closed-loop voltage gain ( AV ) of the Non-inverting Amplifier as follows: 

 
Then the closed loop voltage gain of a Non-inverting Operational Amplifier will be given as: 

 
We can see from the equation above, that the overall closed-loop gain of a non-inverting amplifier will always be greater but never less than one (unity), it is positive in nature and is determined by the ratio of the values of Rƒ and R2. 

If the value of the feedback resistor Rƒ is zero, the gain of the amplifier will be exactly equal to one (unity). If resistor R2 is zero the gain will approach infinity, but in practice it will be limited to the operational amplifiers open-loop differential gain, ( AO ). 

We can easily convert an inverting operational amplifier configuration into a non-inverting amplifier configuration by simply changing the input connections as shown 

QUESTION 7 
If we made the feedback resistor, Rƒ equal to zero, (Rƒ = 0), and resistor R2 equal to infinity, (R2 = ∞), then the circuit would have a fixed gain of “1” as all the output voltage would be present on the inverting input terminal (negative feedback). This would then produce a special type of the non-inverting amplifier circuit called a Voltage Follower or also called a “unity gain buffer”. 

The advantage of the unity gain voltage follower is that it can be used when impedance matching or circuit isolation is more important than amplification as it maintains the signal voltage. The input impedance of the voltage follower circuit is very high, typically above 1MΩ as it is equal to that of the operational amplifiers input resistance times its gain ( Rin x AO ). Also its output impedance is very low since an ideal op-amp condition is assumed. 

 Maisarah binti Mohamad Sattar (1728650)
- ZIEZI EZWANIE BINT
 - ZIEZI EZWANIE BINTI ZAINOL AFANDI

- 1725058

QUESTION 1

Op-Amps are linear devices that have all the properties required for nearly ideal DC amplification. The circuit can perform many mathematical operations that is why it is called operational amplifier. Op-Amps are one of the basic building blocks of analog circuits, since any electronic circuit can be constructed by using op-amp. 

Ideal op-amp can be identified with the following characteristics:

a) Infinite open-loop gain (Avo)
Op-Amp's main function is to amplify the input signal therefore the more open loop gain is the better. 
b) Infinite input impedance 
The input impedance(Zin) is assumed to be infinite to prevent current flowing into the amplifier.
c)Zero output impedance
Current will be supplied enough to the load with zero internal resistance.
d)Infinite bandwith
Ideal Op-Amp can amplify any frequency signal from DC to the highest AC frequencies.
e)Zero input offset voltage(ie. exactly zero out if zero in)

The implication of this model in terms of input currents is there is no current flowing into the amplifier as the input impedance is infinite. Meanwhile, input offset voltage is zero to make sure the ouput is zero.

QUESTION 2

https://padlet-uploads.storage.googleapis.com/315591657/bcfbf9853382388674a9d127891f6f9f/image.png

Based on the circuit above, the operational amplifier is connected with feedback to produce a closed loop operation.  The characteristics for inverting amplifiers are no current flows into the input terminals and the differential input voltage is zero as V1=V2=0 (Virtual Earth).

QUESTION 3

Virtual ground is where the node has voltage almost equal to ground voltage (0V). However, it is not physically connected to the ground. It is useful in Op-Amp circuits analysis and make calculations a lot easier.

QUESTION 4

The reason why we have zero output resistance is because we want to transfer all the output voltage to the load. Examples of load are a speaker, hard disk motor and digital circuits. If the output resistance is not zero, there will be voltage division which will make the load receive weak input.

 

QUESTION 5

 Ideal Summing Amplifier which is also called adder as is a circuit where we can add several signals together. We can change the gain or add another input without messing with the gains of  other inputs. The operation of this ideal summing amplifier is based on the circuit below.

https://padlet-uploads.storage.googleapis.com/315591657/04ce8b3ca4a5fde3a9b89b1c70de3df1/uy.png

Va, Vb and Vc are input signals. These input signals are given to the inverting terminal of the operational amplifier using input resistors like Ra, Rb and Rc. Rf is feedback resistor and RL is load resistor. We can use KCL to get equation : If=Ia+Ib+Ic. After some derivations, we get V0= -(Va+Vb+Vc).
The characteristic for ideal summing amplifier is when there more than one input voltage ends up as one output voltage.


QUESTION 6

Op-Amp is identified as non-inverting format when the output is in phase with the input signal. In this circuit the signal is applied to the non-inverting input of the op-amp. The signal of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor is taken to ground. It has to be applied to the inverting input as it is negative feedback.

Gain in non-inverting amplifier is :
Vout/Vin = Av = 1 + R2/R1


QUESTION 7

The properties of voltage follower are voltage follower will result voltage gain equals to 1, input resistance of voltage follower is infinity and the output resistance is low. The advantage of using voltage follower is it is used to boost the current available from a circuit without increasing the voltage at the same time. Second, the voltage follower does not amplify the voltage but the output current 



DISCUSSION ANSWERS { NUR ALYAA SYAZWANI MOHD ZAIDI - 1725810 }
DISCUSSION ANSWERS { NUR ALYAA SYAZWANI MOHD ZAIDI - 1725810 }

§  Question   1

The ideal Op-Amp Model is in which it includes these characteristics; infinite input impedance, zero output impedance, infinite voltage gain, zero input offset voltage. An operational amplifier or Op-Amp is said to be ideal if it has infinite input resistance and zero input current due to the infinite input impedance and zero output impedance.  This differential amplifier with a single-ended output is commonly known as a high voltage gain amplifier at all frequencies, whereby the internal voltage gain of op-amp decreases at higher frequencies. Therefore, with 0-V on the input pins, some output voltage may result. This is called the offset voltage with either positive or negative polarity. An ideal op amp also includes the negative feedback whereby it is the return of a portion of the output signal to the input signal (out-of-phase). Usually, the infinite voltage gain closed loop (ACL) has a feedback, and the infinite voltage gain open loop (AOL) has no feedback. 

§  Question  2
  

The basic amplifier configurations are inverting amplifier and non-inverting amplifier. The characteristics of an ideal inverting amplifier is when RF  provides a portion of the output back to the input which is called negative feedback. The input signal is applied to the inverting input, resulting to output being reversed.  The circuit operation for the ideal inverting amplifier is when due to negative input remains at ground potential (0-V), it is referred to as virtual ground. Because of the feedback loop, it results to voltage gain in an inverting amplifier according to the formula: Av = -RF / R1

§  Question   3

Ideally the gain of op-amp is infinite. The virtual ground or virtual earth or usually called as virtual short is that the potential at inverting and non-inverting terminal is always same if when any of the input two terminals is grounded, the second terminal will also have ground potential. This happens because of very high input impedance of op-amp, no current flow in both the terminal of op-amp so no voltage drop takes place between these two terminals, resulting to both terminals to have same potential due to virtual ground. 

§  Question   4

The output resistance comes from internal source that has an associated with series resistance. The effective resistance resulted is called the output resistance. The negative feedback lowers output resistance, which is usually low enough for practical purposes that it is considered to be zero. The ideal op-amp has infinite input impedance and zero output impedance because it's easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). The low resistance helps in reducing the noise and disturbance. In order to have the input current to fully enter the amplifier, the input resistance must decrease to ensure it flows easily through the input circuit. 

§  Question   5

The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.In the inverting operational amplifier that the inverting amplifier has a single input voltage, (Vin) applied to the inverting input terminal. If we add more input resistors to the input, each equal in value to the original input resistor, (Rin) we end up with another operational amplifier circuit called a Summing Amplifier, “summing inverter” or even a “voltage adder” circuit as shown above. The easiest way to characterize (characteristic) of summing amplifier is when the input voltage is present to be two or more resulting to an output voltage. In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V1, V2, V3, etc. 

§  Question   6
   
In which the basic amplifier configurations has non-inverting amplifier and inverting amplifier, here are several characteristics and identification to recognize the non-inverting amplifier. First of all for the characteristics, it is typical if the signal is applied to the inverting negative input, the output will be inverted. Meanwhile, if the signal is applied to the inverting positive input, the output will not be inverted. As we know, the op amp open loop gain is extremely high. Therefore, the output voltage will only responds to the difference in potential between its two inputs. Output voltage swing also will be limited to within 103 V of the supply voltage. Proceeding to the circuit operation, as the input pins on an op-amp are essentially open circuits, no voltage drops across RB.  This is because the input impedance infinite, therefore the voltage drop is 0-V at RB unless it is stated that the value of RB can be ignored. Feedback resistor or RF and R1 wil form a voltage divider across output voltage and find the voltage gain using Av = (RF/ R1) + 1. 

§  Question   7

A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. The advantages of using this voltage follower circuit is so that when a circuit has a very high input impedance, very little current is drawn from the circuit. If you know ohm's law, you know that current, I=V/R. Thus, the greater the resistance, the less current is drawn from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load. Other than that, the reason voltage followers are used because of their importance in voltage divider circuits. This again deals with ohm's law. According to ohm's law, voltage= current x resistance (V=IR). 
In a circuit, voltage divides up or is allocated according to the resistance or impedance of components. Because an op amp has a very high input impedance, the majority of voltage will fall across it, (since it's so high impedance). So it's very valuable when used in a voltage divider circuit because strategically doing so can allow a designer to supply sufficient voltage to a load. 

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MUHAMMAD ZULKARNAIN BIN ZAKARIA

1723395

SECTION 6

1.       Ideal Op Amp is when the input impedance (input resistance) is infinity and the output impedance (output resistance) equal to zero. Its implication to the input current and voltage, they will be block by this input impedance which is infinity.

2.       Input resistance is infinite.

Output resistance is zero.

Differential input voltage equal to zero.

Internal differential gain is infinite.

No current flow.

V1 – V2 = 0, V1=V2

So that it will give out maximum output voltage or current with such minimum input voltage or current.

3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.

4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.

5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.

6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.

7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.
infinite.

No current flow.

V1 – V2 = 0, V1=V2

So that it will give out maximum output voltage or current with such minimum input voltage or current.

3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.

4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.

5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.

6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.

7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.

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MUHAMMAD ZULKARNAIN BIN ZAKARIA

1723395

SECTION 6

1.       Ideal Op Amp is when the input impedance (input resistance) is infinity and the output impedance (output resistance) equal to zero. Its implication to the input current and voltage, they will be block by this input impedance which is infinity.

2.       Input resistance is infinite.

Output resistance is zero.

Differential input voltage equal to zero.

Internal differential gain is infinite.

No current flow.

V1 – V2 = 0, V1=V2

So that it will give out maximum output voltage or current with such minimum input voltage or current.

3.       In Ideal Op Amp, the input resistance is infinite, so the virtual ground is a concept for calculation purposes and analyzing. So, that we know where the current goes and easier to analyze.

4.       The significance is so that the amplifier will be efficient which it will give the maximum output voltage.

5.       Different source can be sum to a single source because of all of it will connect to one of the terminal of amplifier.

6.       Non Inverting Amplifier is when the voltage source is connected to the positive (non-inverting) terminal of the amplifier and no voltage source connected to the negative (inverting) terminal of the amplifier. Resistor from inverting terminal form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of those resistor.

7.       Voltage follower is when the gain is equal to 1; Vo = Vi. The advantage of the voltage follower is that it can be used to maintains the signal voltage.

*P/s: Advantage of using the circuit in the discussion question. First, the circuit is using inverting amplifier. The op amp inverting amplifier circuit is very easy to design and can be implemented with a very limited number of additional components.

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MUHAMMAD FAKHRUL HADI BIN ZAMZURI (1726963)

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MUHAMMAD FAKHRUL HADI BIN ZAMZURI (1726963)

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Q1) An ideal op amp is an op amp that has perfect conditions to allow it to function as an op amp with 100% efficiency. Ideal op amps will have infinite voltage gain, infinitely high impedance, zero output impedance, its gain is independent of input frequency, it has zero voltage offset, its output can swing positive or negative to the same voltages as the supply rails, and its output swings instantly to the correct value.
The implications of this ideal model in terms of input currents and voltages :
1. Infinite voltage gain
2. Infinite input impedance
3. Zero output impedance
4. Infinite bandwidth
5. Zero input offset voltage

Q2) Inverting amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. With the operational amp having such characteristics that are close to ideal, it is rather easy to design and build circuits using the IC op amp.
The characteristics of an ideal op-amp are as follows :
1. Infinite bandwidth due to the ideal gain inside of the op-amp
2. Infinite open-loop gain A
3. Infinite or zero common-mode gain
4. Input impedance of an infinite value
5. Output impedance of zero

Q3) In op-amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground. This concept is very useful in analysis of op-amp circuits and it will make a lot of calculations very simple.
This is how the virtual ground concept is employed in inverting amplifier :
Q4) Impedance is the relationship between voltage and current. It's a combination of resistance (frequency-independent, resistors) and reactance (frequency-dependant, inductors and capacitors).
An ideal op-amp has infinite input impedance. This means that there can be no current into or out of the inverting and non-inverting input terminals.
An ideal op-amp has zero output impedance. This means that the output voltage is independent of output current.
To summarize, input impedance is "high" (ideally infinite). Output impedance is "low" (ideally zero).

Q5) The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.
In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V1, V2, V3, etc.

Q6) In this Non-inverting Operational Amplifier, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit we saw in the last tutorial whose output gain is negative in value. The result of this is that the output signal is “in-phase” with the input signal.
An ideal op-amp “No current flows into the input terminal” of the amplifier and that “V1 always equals V2”.

Q7) A voltage follower is a op-amp circuit which has a voltage gain of 1. The op amp does not provide any amplification to the signal and the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage.
An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used.
A voltage follower uses an op-amp to set the voltage on the output to be the same as the voltage on the input. It does however have limited drive capability

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QUESTION 1:
The ideal Op Amp (Operational Amplifier) is a model that has three circuit element. It is a voltage controlled voltage source with very high gain. It is modeled with differential input terminals and has a single output terminal. The characteristics of an ideal amplifier are: 
Infinite voltage gain
Infinite input impedance
Zero output impedance

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1. - An amplifier with infinite input impedance, infinite open-loop gain, zero output impedance and infinite bandwidth.
- In the terms of input current, the input resistance of this ideal Op Amp is infinite, which can make the current in each input to be zero.
- In terms of voltage, the voltage gain is independent of the output current.

2. - No Current Flows into the Input Terminals.
- The Differential Input Voltage is Zero as V1 = V2 = 0

3. Voltage of a node that are almost equal to the virtual ground (V=0)

4. - To transfer all of the output voltage to the load.
- When the voltage drops, it will amplify the signal.

5. - Ideal summing amplifiers is applied when the two or more different signals need to be combined.
- These different signal sources will be added together by this amplifier.

6. Op-Amp is identified as non-inverting format when the output is in phase with the input signal. The signal is applied to the non-inverting input of the op-amp. The signal of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor is taken to ground. It must be applied to the inverting input as it is negative feedback.

7. A op-amp circuit which has a voltage gain of 1. The output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage

The advantages of such voltage follower circuit are:

- Very large input resistance, of the order of M
- Low output impedance, almost zero. Hence it can be used to connect high impedance source to a low impedance load, as a buffer.
- It has large bandwidth.
- The output follows the input exactly without Phase shift.

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1.Describe the ideal op-amp model

-have infinite voltage gain

-infinitely high impedance

-zero output impedance

-its gain is independent of input frequency

- has zero voltage offset

-its output can swing positive or negative to the same voltages as the supply rails

and its output swings instantly to the correct value.

4.What is the significance of zero output resistance

output impedance is zero because that's what amplifiers do.They convert a small signal into a larger one and  suppose the ratio of input to output impedance could be one measure of such.

5.decribe the operation and characteristics of ideal summing amplifier

n numbers of input terminal are connected in parallel. Here, in the circuit, the non-inverting

terminal of the op amp is grounded, hence potential at that terminal is zero. As the op amp is

considered as ideal op amp, the potential of the inverting terminal is also zero. So, the

electric potential at node 1, is also zero. From the circuit, it is also clear that the current i is

the sum of currents of input terminals.

Now, in the case of ideal op amp the current at the inverting and non-inverting terminal are

zero. So, as per Kirchhoff Current Law, the entire input current passes through the feedback path of resistance Rf. That means,

From, equation (i) and (ii), we get,

This indicates that output voltage v₀ is weighted sum of numbers of input voltages.

6.describe the operation and  chracteristics of the ideal non inverting amplifiers

Then using the formula to calculate the output voltage of a potential divider network, we can calculate the closed-loop voltage gain ( AV ) of the Non-inverting Amplifier as follows:

Then the closed loop voltage gain of a Non-inverting Operational Amplifier will be given as:

We can see from the equation above, that the overall closed-loop gain of a non-inverting amplifier will always be greater but never less than one (unity), it is positive in nature and is determined by the ratio of the values of Rƒ and R2.

If the value of the feedback resistor Rƒ is zero, the gain of the amplifier will be exactly equal to one (unity). If resistor R2 is zero the gain will approach infinity, but in practice it will be limited to the operational amplifiers open-loop differential gain, ( AO ).

We can easily convert an inverting operational amplifier configuration into a non-inverting amplifier configuration by simply changing the input connections as shown

7.describe the voltage follower.what are the advantages of using this circuit

The voltage follower is the safest and easiest transistor amplifier circuit to build. Its purpose is to provide approximately the same voltage to a load as what is input to the amplifier but at a much greater current. In other words, it has no voltage gain, but it does have current gain.

the advantage of this circuit is that the op-amp can provide current and power gain; the op-amp draws almost no current from the input.

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Muhammad Zahin Hafifi Bin Masrizal (1725353)                                                                                                                                Question 1                                                                                                                                                                                                          1. Internal differential gain Aod is infinite.                                                                                                                                                   2. Differential input voltage (v2-v1) is zero.                                                                                                                                                 3. Effective input resistance is infinite.                                                                                                                                                         4. Output resistance is zero so output voltage is connected directly to dependent voltage source.                                                                                                                                                                                                                                                     Question 2                                                                                                                                                                                                Voltage at node 1 (inverting)  =  voltage at node 2 (non-inverting ) KCL at node 1:I1 – I2 – Iin = 0(Vi – 0) / R1 = (0 – Vo) / R2Vi / R1 = - Vo / R2Vo/Vi =  - R2 /R1Voltage gain, Av = V0/Vi = -R2/R1Input resistance, Ri = Vi/I1 = R1Output resistance, R0 = V0/I2 = R2                                                                                                                                                                                                                                                                                                                                                                                                               Question 3                                                                                                                                                                                                  Virtual Ground is making a node or a connection virtually ground. By the term virtually ground mean, it is not physically connected to ground but voltage at that point/node is 0V. So we refer to it as ground. This concept is used for analysis of operational amplifier circuits. It makes analysis of OP-Amp based circuits very easy.                                                                                                                                                                                                                                                                           Question 4                                                                                                                                                                                                       The zero output resistance is important because it is easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). It is not so easy to go the other way. We need something that can amplify. An op-amp as a voltage follower is one way to transform a high source impedance into a low source impedance.                                                                                                                                                                                                                  Question 5                                                                                                                                                                                                           If the input resistances of a summing amplifier are connected to potentiometers, the individual input signals can be mixed together by varying amounts. We can change the gain or add another input without messing with the gains of the other inputs. Just remember that the circuit also inverts the input signals. Not a big deal. If you need the opposite polarity, put an inverting stage before or after the summer.                                                                                                                                                                                                                                                                                                                                                     Question 6                                                                                                                                                                                                     Non-inverting amplifier is one in which the output is in phase with respect to the input. The feedback is applied at the inverting input. However, the input is now applied at the non-inverting input. The output is a non-Inverted (in terms of phase) amplified version of input. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs.                                                                                                                                                                                                                                                          Question 7                                                                                                                                                                                                           A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used

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Muhammad Zahin Hafifi Bin Masrizal (1725353)                                                                                                                                Question 1                                                                                                                                                                                                          1. Internal differential gain Aod is infinite.                                                                                                                                                   2. Differential input voltage (v2-v1) is zero.                                                                                                                                                 3. Effective input resistance is infinite.                                                                                                                                                         4. Output resistance is zero so output voltage is connected directly to dependent voltage source.                                                                                                                                                                                                                                                     Question 2                                                                                                                                                                                                Voltage at node 1 (inverting)  =  voltage at node 2 (non-inverting ) KCL at node 1:I1 – I2 – Iin = 0(Vi – 0) / R1 = (0 – Vo) / R2Vi / R1 = - Vo / R2Vo/Vi =  - R2 /R1Voltage gain, Av = V0/Vi = -R2/R1Input resistance, Ri = Vi/I1 = R1Output resistance, R0 = V0/I2 = R2                                                                                                                                                                                                                                                                                                                                                                                                               Question 3                                                                                                                                                                                                  Virtual Ground is making a node or a connection virtually ground. By the term virtually ground mean, it is not physically connected to ground but voltage at that point/node is 0V. So we refer to it as ground. This concept is used for analysis of operational amplifier circuits. It makes analysis of OP-Amp based circuits very easy.                                                                                                                                                                                                                                                                           Question 4                                                                                                                                                                                                       The zero output resistance is important because it is easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). It is not so easy to go the other way. We need something that can amplify. An op-amp as a voltage follower is one way to transform a high source impedance into a low source impedance.                                                                                                                                                                                                                  Question 5                                                                                                                                                                                                           If the input resistances of a summing amplifier are connected to potentiometers, the individual input signals can be mixed together by varying amounts. We can change the gain or add another input without messing with the gains of the other inputs. Just remember that the circuit also inverts the input signals. Not a big deal. If you need the opposite polarity, put an inverting stage before or after the summer.                                                                                                                                                                                                                                                                                                                                                     Question 6                                                                                                                                                                                                     Non-inverting amplifier is one in which the output is in phase with respect to the input. The feedback is applied at the inverting input. However, the input is now applied at the non-inverting input. The output is a non-Inverted (in terms of phase) amplified version of input. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs.                                                                                                                                                                                                                                                          Question 7                                                                                                                                                                                                           A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used

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1)The IC Op-amp comes so close to ideal performance that it is useful to state the characteristics of an ideal amplifier without regard to what is inside the package.

i)Infinite voltage gain
ii)Infinite input impedance
iii)Zero output impedance
iv)Infinite bandwidth
v)Zero input offset voltage

Implications :
i) input resistance is infinite, so current flow into either input terminals=0
ii) differential input offset voltage is 0.

2) Applying a resistor across the Op Amp to cause an affect called Negative feedback. This effect produces a gain of amplifier in a closed loop. Negative feedback results in the output voltage to have a opposite signal than input voltage characteristics.

3)Virtual Ground is a node of a circuit  that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence.

4)The output impedance of the ideal operational amplifier is assumed to be zero acting as a perfect internal voltage source with no internal resistance so that it can supply as much current as necessary to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load.

5) ideal summing circuit is a circuit that add several signals and combine voltages on inputs into a output voltage. We can change the gain or add another input without messing with the gains of  other inputs.

6) Op-Amp is identified as non-inverting format when the output is in phase with the input signal. In this circuit the signal is applied to the non-inverting input of the op-amp. The signal  of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor    is taken to ground. It has to be applied to the inverting input as it is negative feedback.

7) A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1.
This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage,      meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.

Voltage Follower, using an OpAmp, may have a rather precise copying of Vin onto Vout, with ability to handle varying loads while still performing that precise copying.

# data[].attributes.headline
Mohamad Haziq Bin Mohamad Faizal (1727001)

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Mohamad Haziq Bin Mohamad Faizal (1727001)

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Question 1
The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions.
Question 2
The characteristics of the ideal inverting amplifier is no current flows into the input terminalsand the differential input voltage is zero.
Question 3
Virtual Ground is a node of a circuit  that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence.
Question 4
An ideal constant voltage power supply should have zero output impedance so that changes in the load such as higher load currents do not cause a voltage drop at the output. In addition, the low impedance helps in reducing the noise and interference. When the supply has high impedance, high load current causes a voltage drop across this impedance and lower the output voltage.
Question 5
A summing amplifier is a one kind of circuit which is used to add when the two or more signals need to be combined like in audio mixing applications. The sounds from various musical devices can be changed to an exact voltage level by using transducers, and linked as i/p to a summing amplifier. These different signal sources will be added together by this amplifier, and the added signal is directed to an audio amplifier. Question 6The basic non-inverting amplifier circuit using an op-amp is shown above. In this circuit the signal is applied to the non-inverting input of the amplifier. However the feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It is the value of these two resistors that govern the gain of the operational amplifier circuit. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs. As the input to the op-amp draws no current this means that the current flowing in the resistors R1 and R2 is the same. The voltage at the inverting input is formed from a potential divider consisting of R1 and R2, and as the voltage at both inputs is the same, the voltage at the inverting input must be the same as that at the non-inverting input.
Question 7
Voltage follower is an op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.

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Question 1
Ideal Op-Amp are as follows:
- infinite input impedance and zero output impedance.
-use dual power supplies
-have more than one compensation pin.
-the offset voltage due to the 0 V input.

Implications :
-input resistance is infinite, so no current flow into either input terminals
-differential input offset voltage is zero

Question 2
To produce a very stable op amp system, a negative feedback has to be created by sending back the signal to the inverting input/amplifier. This is done by using an external feedback resistor hence forces the differential input voltage towards zero.
Characteristics:
o No current flows into input terminal
o Differential input voltage is zero

Question 3
Virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). This concept will make almost all calculations becomes simple. It is not electrically connected to the ground since it is virtual. This concept is only valid if negative feedback is applied like in inverting amplifier.

Question 4
The output impedance of the ideal operational amplifier is assumed to be zero acting as a perfect internal voltage source with no internal resistance so that it can supply as much current as necessary to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load. Real op-amps have output impedances in the 100-20kΩ range.

Question 6
The input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a voltage divider network. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability.
Characteristic:
• output signal is “in-phase” with the input signal.

Question 7
As the input signal is connected directly to the non-inverting input of the amplifier the output signal is not inverted resulting in the output voltage being equal to the input voltage, Vout = Vin. This then makes the voltage follower circuit ideal as a Unity Gain Buffer circuit because of its isolation properties.
Advantages:
• It can be used when impedance matching or circuit isolation is more important than amplification as it maintains the signal voltage.
• to isolated circuits from each other hence separating one filter stage from the other

Mohamad Norfaieqwan bin Kamarudin (1727771)

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Question 1

1. Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages.

- Ideal Op-Amp model is a three terminal circuit element that is modelled as a

voltage-controlled voltage source.
- It comes so close to ideal performance that it is useful to state the characteristics of an ideal amplifier without regard to what is inside the package.

Its characteristics are :

1. Infinite voltage gain

2. Infinite input impedance

3. Zero output impedance

4. Infinite bandwidth

5. Zero input offset voltage (i.e., exactly zero out if zero in).

The implications of this model are

• Infinite common-mode rejection

• Infinite power supply rejection

• Infinite output voltage range

• Infinite output current capability

• Infinite open-loop bandwidth

• Infinite slew rate

• Zero output resistance

• Zero input-bias currents and offset current

• Zero input-offset voltage

2. Describe the operation and characteristics of the ideal inverting amplifier.

An ideal inverting-amplifier circuit is built by grounding the positive input of the operational amplifier and connecting resistors R1 and R2, called the feedback network, between the inverting input and the signal source and amplifier output node.

Characteristics are :

No Current Flows into the Input Terminals

The Differential Input Voltage is Zero as V1 = V2 = 0 (Virtual Earth)

Operation

In the amplifier circuit, the inverting-input terminal of the operational amplifier is at ground potential, 0 V, and is referred to as a virtual ground.

The ideal Operational amplifier adjusts its output to whatever voltage is necessary to force the differential input voltage to zero.

Because of the virtual ground at the inverting input, input voltage vi appears directly across resistor R1 and establishes an input current vi/R1. The op amp forces this input current to flow through R2 developing a voltage drop of vi · (R2/R1). Thus vo = −vi (R2/R1) and Av = −(R2/R1).

3. What is the concept of virtual ground?

Virtual ground is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential.

In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence.

A voltage divider, using two resistors, can be used to create a virtual ground node. If two voltage sources are connected in series with two resistors, it can be shown that the midpoint becomes a virtual ground if  Vout/Vin = -Rf/Rin.

V out/ V in = − R f /R in

4. What is the significance of a zero output resistance?

The voltage may not drop across it and it would not receive the signal.

It would draw significant amounts of current into it. Thus, it would be a large load on the circuit.

5. Describe the operation  and characteristics of the ideal summing amplifier

The summing amplifier is a handy circuit enabling you to add several signals together.

Can change the gain or add another input without messing with the gains of the other inputs.

Operation

Keep the potential of the negative terminal very close to the positive terminal. In this case, keep the negative terminal close to 0V (virtual ground).

The op amp essentially nails one leg of R1, R2 and R3 to a 0V potential. This makes it easy to write the currents in these resistors.

I1 = V1 / R1;    I2 = V2 / R2;   I3 = V3 / R3

·         According to our friend Kirchoff, we get

I = I1 + I2 + I3

·        So the output becomes Vo = -RF x I.

Vo = - RF ( V1 / R1  +  V2 / R2  +  V3 / R3)

= - ( V1 · RF / R1  +  V2 · RF / R2  +  V3 · RF / R3 )

·        The gain for each input can be controlled by a single resistor:

K1 = -RF/R1,

K2 = -RF/R2

K3 = -RF/R2.

6. Describe the operation and characteristics of the ideal non inverting amplifier

The input signal is applied to the positive or (noninverting) input terminal of

the operational amplifier, and a portion of the output signal is fed back

to the negative input terminal (negative feedback).

Analysis of the circuit is performed by relating the voltage at V1 to both input voltage Vi and output voltage Vo.

Operation

·        Since the voltage across the inputs of the op amp must be zero , input voltage vi appears directly across resistor R1 and establishes a current vi/R1.

·        This current flows down through R2 developing a scaled replica of vi {i.e., vi · (R2/R1)} across R2.

·        The output is the sum of the voltages across R1 and R2 yielding vo = vi + vi (R2/R1) and Av = 1 + R2/R1.

7. Describe the voltage follower. what are the advantages of using this circuit.

The value of R1 is infinite and that of R2 is zero.

Advantages

Provides a gain of 1 with infinite input resistance and zero output resistance and therefore provides a tremendous impedance-level transformation while maintaining the level of the signal voltage.

Does not require any input current, yet can drive any desired load resistance without loss of signal voltage.

To transfer a voltage from one point in the circuit to another point without directly connecting the points together .

-Muhd Zulhelmie Samsuri
-1720589

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Nuranisa Suhada Binti Abd Rahim (1721952)

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Nuranisa Suhada Binti Abd Rahim (1721952)

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Answer 1

The current in or out of either input is negligible .No current flowing in and out of the input terminals of the op-amp (high input impedance of op-amp). If the output is not in saturation, the voltage between the inverting and non-inverting input terminals is zero.

Answer 2

In this Inverting Amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. When dealing with operational amplifiers there are two very important rules to remember about inverting amplifiers, these are: “No current flows into the input terminal” and that “V1 always equals V2”. However, in real world op-amp circuits both of these rules are slightly broken.

This is because the junction of the input and feedback signal ( X ) is at the same potential as the positive ( + ) input which is at zero volts or ground then, the junction is a “Virtual Earth”. Because of this virtual earth node the input resistance of the amplifier is equal to the value of the input resistor, Rin and the closed loop gain of the inverting amplifier can be set by the ratio of the two external resistors.

Answer 3

A virtual ground, sometimes known as  a virtual short. In this case, it would be referred to as a virtual ground. At least for calculation of current, we can consider that there is actually a ground between here and … If it was a real ground, we would have no output because simply the signal would come in and go straight to ground, it would never get to the amp. This is a virtual ground but because for calculation purposes and analyzation, it does look like a ground.

If we took this voltage in and we divided it by the resistance here, we would get a current and that current is not going to flow into the op amp because it has infinite resistance. That current will be felt through this resistance up here. Sometimes this is referred to as RF or feedback resistor. The value that flows through that current will develop a voltage and that will result in our output.

We'll look at negative feedback in more detail later, but what we're going to find is that we can get a very predictable gain based upon the sizes of these two components.

The same concept will result down here. We call this a virtual ground. Oftentimes, in this case, it would be called a virtual short because if you calculate the value of this voltage across this component, then we can do basically the same kind of calculation.

Answer 4

The output of an op amp comes from a source internal to it that has an associated series resistance. Here we see the input and we see an associated series resistance that's going to become our output resistance.

The effective resistance is called the output resistance of an op amp. We looked at that back in the transistor section.

Negative feedback lowers the effective output resistance. It is low enough that for practical purposes, we will consider it to be zero.

Answer 5

The output voltage of a summing amplifier is proportional to the negative of the algebraic sum of its input voltages. Hence, the name summing amplifier. A summing amplifier is an inverted OP-Amp that can accept two or more inputs.

Three voltages V₁, V₂ and V₃ are applied to the inputs and produce currents I₁, I2 and I₃.

The inverting input of the OP-Amp is at virtual ground (0 V) and there is no current to the input.

So, the three input currents I₁, I2 and I₃ combine at the summing point A and form the total current If which goes through Rf as shown in figure above.

When all the three inputs are applied, the output voltage is

Thus the output voltage is proportional to the algebraic sum of the input voltages.

If Rf =R1=R₂=R₃=R, then, we have

Thus, when the gain of summing amplifier is unity, the output voltage is the algebraic sum of the input voltages.

Answer 6

In the non-inverting, we're going to send in this input signal and since it's the non-inverting, the output will be the same phase as the input.

Then we have a portion of that is fed back to the inverting input and so, notice, that is coming in like this. It's in the same phase. Recall that an op amp amplifies the difference. If we had the same phase of input on both inputs, then, again, this will tend to attenuate the signal. This idea of negative feedback is that the feedback opposes the original input signal.

Again, this will attenuate the total gain from what we would have in AOL, but, again, it will make for an ACL, which is a closed-loop gain, and it will be an extremely predictable amount of gain.
Since the op amp ideally has infinite input resistance, no current flows into the input. Remember, we've mentioned that several times, that this effectively has infinite input impedance. What we're going to say is that we're going to send in an input voltage and it will go across this resistance.

Answer 7

There are two important pros of the voltage follower which are the required unity gain is much more precise if compared with an emitter follower and the output resistance is much more smaller.

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NUR HUSNINA BINTI MUHAMAD ZURAIDI (1723394)

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NUR HUSNINA BINTI MUHAMAD ZURAIDI (1723394)

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Question 1

Op Amp is an integrated circuit that have well defined operating characteristics. The characteristics for ideal op amp are :

1. Infinite input impedance

2. Zero output impedance

3. Infinite voltage gain

4. Gain is independent of input frequency

5. Infinite bandwidth

6. Zero input offset voltage

7. Output can swing positive or negative to the same voltages as the supply rails

The implications of this ideal model in terms of input current and voltages :

1. Input resistance of ideal Op Amp is infinite, so the input current will be zero which is no current flows.

2. Voltage gain is independent to output current

Question 2

The operation and characteristics of ideal inverting amplifier

The input signal is applied in the inverting input terminal, so the output being reversed

Rf (feedback resistor) connected between output and inverting input terminals

The junction is virtual earth because the feedback signal is at the same potential as positive input which is zero volts

Virtual earth node the input resistance of the amplifier = the value of Rin

Closed loop gain of the inverting amplifier = the ratio of two internal resistor

The output is the inverse or 180° out of phase with the input

Vout = -(Rf/Rin) x Vin

The characteristics :

1. No current flows into the input terminals

2. The difference of input voltage is zero

Question 3

Concept of virtual ground

The voltage at that particular node is almost equal to ground voltage (0V)

A concept that made for easy explanation and calculation purposes

Not electrically connected to ground

Voltage is approximately zero

Not able to sink infinite current

The concept is useful to analyse op amp when negative feedback is employed

Question 4

The significance of a zero output resistance

The measure of the opposition to current flow

Output resistance comes from internal source that has associated series resistance

The output resistance of the op amp is the effective resistance

The negative feedback will lower the effective output resistance, and considered as zero for practical purposes

Question 5

The operation and characteristics of the ideal summing amplifier

Operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage

The output voltage becomes proportional to the sum of the input voltages

- Vout = (Rf/Rin) (V1 + V2 + V3 ……..etc)

Input signals are effectively isolated from each other by the virtual earth node at the inverting input of the op amp

When the summing point is connected to the inverting input of the op amp, the circuit will produce the negative sum of input voltages and vice versa

Question 6

The operation and characteristics of the ideal non inverting amplifier

The output is in the same sense or in phase with the input

Basic circuit :

The feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to the ground

The gain of the amplifier is exceedingly high

When the input draws no current, so the current flows in R1 and R2 is the same

Voltage at inverting input formed from a potential divider consist of R1 and R2, the voltage at both input is same, so voltage at inverting input must be the same as the non inverting input

Vin = Vout x R1 / (R1 + R2)

Question 7

The voltage follower and the advantages of the circuit

Called as unity-gain amplifier, buffer amplifier or isolation amplifier

Op-amp has a voltage gain of 1

Does not provide any amplification to the signal

Output voltage = input voltage

Act as a buffer, provide no amplification to the signal

Draws a little current from power source

Not disturbing the original circuit

Give same voltage signal as output

Isolate the circuit so the power of the circuit disturbed very little

Importance in voltage divider circuits

Allow designer to supply efficient voltage to load

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Question 1
The characteristic of ideal op amp:
- Infinite voltage gain
-Infinite input impedance (nearly to very large value so it considered as infinte)
-Zero output impedance (the value close to zero)
-Infinite bandwidth
-Zero input offset voltage
Based on these characteristics, we can say that current cannot flow in or out from input terminal. Plus, the output will make the voltage difference between input become zero in the close loop.

Question 2

In this Inverting Amplifier circuit the operational amplifier is connected with feedback to produce a closed loop operation. When dealing with operational amplifiers there are two important rules to remember about inverting amplifiers:
-No current flows into the input terminal
-V1 always equals V2
(But these two rules are invalid in real world op amp circuit)

This is because the junction of the input and feedback signal ( X ) is at the same potential as the positive ( + ) input which is at zero volts or ground then, the junction is a “Virtual Earth”. Because of this virtual earth node the input resistance of the amplifier is equal to the value of the input resistor, Rin and the closed loop gain of the inverting amplifier can be set by the ratio of the two external resistors.

Question 3
By the term virtual ground, it does not mean it connected to the ground, but the value is about to similar with zero value which is considered as ground.

Consider an Inverting Op-amp Configuration with negative feedback. Referring to Ideal Op-Amp parameters, Input Impedance is ∞. So ideally no current flows through Op-amp.

As there is no current flowing through Op-amp, Current (Ia) flowing through node Va will be ‘0’. And by Ohm’s Law we could conclude that Va=0. V= I X R, as I is 0 perhaps V will also be ‘0’.

Question 4
We want the op-amp to be able to drive its output pin to the required voltage, irrespective of how much load there is on that output. Again, we want minimum “corruption” of the signal, so the lower the output resistance, the better the op-amp is able to “override” the influence of any surrounding circuitry by sinking or sourcing as much current as required.  In reality, no op-amp is “ideal”, but they come close enough that they can be assumed to be “ideal” in calculations for most practical purposes.

Question 5
The summing amplifier is a handy circuit enabling us to add several signals together. Its easy to understand that the main operation of op amp is to keep the potential of the negative terminal very close to the positive terminal.  In this case, keep the negative terminal close to 0V (virtual ground). The op amp essentially nails one leg of resistors in the circuit to a 0V potential.

Question 6

1.  As for the non-inverting amplifier, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout.

Question 7
Voltage follower is an op amp circuit whose output voltage straight away follows the input voltage. That is output voltage is equivalent to the input voltage. Op-amp circuit does not provide any amplification. Thus, voltage gain is equal to 1. They are similar to discrete emitter follower. The other names of voltage follower are Isolation Amplifier, Buffer Amplifier, and Unity-Gain Amplifier. The voltage follower provides no attenuation or no amplification but only buffering. This circuit has an advantageous characteristic of very high input impedance.
This high input impedance of voltage follower is the reason of it being used in several circuits. The voltage follower gives an efficient isolation of output from the input signal.

The advantage of Voltage Follower :

Provides power gain and current gain

Low output impedance to the circuit which uses the output of the voltage follower

The Op-amp takes zero current from the input.

Loading effects can be avoided

Raja Amirul Hisham bin Raja Zafri (1721423)

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1) Infinite voltage gain.
2) Have infintely high input  impedance. Ensure that the op amp causes no loading in the circuit. The lower the input impedance, the more current that an op amp will draw. The higher the impedance, the lower the current that an op will draw.
3) Have zero output impedance. We want Op amp to have zero voltage so that the maximum voltage will be transferred to the output load.  In order for the voltage to drop across the output load, that load must be of greater impedance than the output of the op amp.
4) The gain that the op amp produces will be independent of frequency. This means that regardless of the frequency of the input signal going into the op amp.
5)  If no voltage is applied to the inverting and nonnverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins.

Q2
1) No Current Flows into the Input Terminals.
2) The Differential Input Voltage is Zero as V1 = V2 = 0

Q3
1)   A voltage divider,  using two resistors, can be used to create a virtual ground node.  If two voltage sources are connected in series with two resistors, it can be shown that the midpoint becomes a virtual ground
2)

Gain = Vo/Vin

As gain is infinite, Vin = 0

Vin = V2 – V1

In the above circuit V1 is connected to ground, so V1 = 0. Thus V2 also will be at ground potential.
3)  Voltage is approximately Zero .
4)  Not able to sink infinite current .
5)   Not electrically connected to Ground .

Q4
1) To transfer all output voltage to the load.
2) As the voltage drops, it will amplify the signal.

Q5
1)

Summing Amplifier Circuit

The summing amplifier circuit is shown below. In the circuit below Va, Vb and Vc are input signals. These input signals are given to the inverting terminal of the operational amplifier using input resistors like Ra, Rb and Rc. In the above manner, the number of input signals can be given to the inverting i/p. Here, Rf is feedback resistor and RL is the load resistor. Noninverting terminal of the operational amplifier is given to the ground terminal using Rm resistor. By applying KCL at node V2 we can get the following equation.

If + Ib= Ia + Ib + Ic

The input resistance of an ideal operational amplifier is near to infinity, so we can neglect V2 and Ib

If= la + lb + lc

The first equation can be written as

(V2-V0)/Rf = Va/Ra + Vb/Rb + Vc/ Rc

By neglecting V2 we can get the following equation

-V0/Rf = Va/Ra + Vb/Rb + Vc/ Rc

V0 = -Rf (Va/Ra + Vb/Rb + Vc/ Rc)

V0 = -(Rf/Ra)/Va + (Rf/Rb)Vb + (Rf/ Rc) Vc

If the values of resistors Ra, Rb and Rc are same then the above equation can be written as

Vo= ( Va + Vb + Vc) X –( Rf/R)

If the values of R and Rf are similar, then the equation becomes
V0 = -(Va + Vb + Vc)

Q6
1)In this configuration, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value in contrast to the “Inverting Amplifier” circuit we saw in the last tutorial whose output gain is negative in value. The result of this is that the output signal is “in-phase” with the input signal.

Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout as shown below.

Q7
1)

A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1.

This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.

2)

Voltage Followers Draw Very Little Current

When a circuit has a very high input impedance, very little current is drawn from the circuit. If you know ohm's law, you know that current, I=V/R. Thus, the greater the resistance, the less current is drawn from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load.

Let's look at both illustrations below:

The below circuit is a circuit in which a power source feeds a low-impedance load.

In this circuit above, the load demands and draws a huge amount of current, because the load is low impedance. According to ohm's law, again, current, I=V/R. If a load has very low resistance, it draws huge amounts of current. This causes huge amounts of power to be drawn from the power source and, because of this, causes high disturbances and use of the power source powering the load.

Now let's look at the circuit below, connected to an op-amp voltage follower:

This circuit above now draws very little current from the power source above. Because the op amp has such high impedance, it draws very little current. And because an op amp that has no feedback resistors gives the same output, the circuit outputs the same signal that is fed in.

This is one of the reasons voltage followers are used. They draw very little current, not disturbing the original circuit, and give the same voltage signal as output. They act as isolation buffers, isolating a circuit so that the power of the circuit is disturbed very little.

MUHAMMAD FARIS BIN NOR APANDI (1726779

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Answer 1 :

The ideal op amp is a three terminal circuit element that is modeled as a voltage-controlled voltage source. That is, its output voltage is a gain multiplied by its input voltage. The input voltage is the difference voltage between the two input terminals. The output voltage is measured with respect to the circuit ground node.

Then, In an ideal op amp, if no voltage is applied to the inverting and noninverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins. The current into terminal 1 and signal into terminal 2 are both zero. The terminal characteristics of the ideal op amp satisfy four conditions. These are as follows:

1. The current in each input lead is zero.

2. The output voltage is independent of the output current.

3. The voltage gain A is independent of frequency.

4. The voltage gain A is very large, approaching infinity in the limit

Answer 2:

Inverting amplifiers are used as summing amplifiers, which sums the voltage present on multiple inputs and combines them into a single output voltage. The below figure, illustrates the amplifier's inverting configuration.

There are an operation amplifier and two resistors R1 and R2 inside of the inverting configuration. The second resistor, R2 is connected from terminal 3 (output terminal), back to terminal 1, which is the inverting (-) input terminal. As R2 is connected in this manner, we can apply negative feedback, which is the process of "feeding back" a small portion of the output signal back into the input terminal. However, in order to make the feedback negative, the output signal must be fed into the inverting terminal of the operation amplifier. Also, if R2 was connected between the output terminal 3 and the input terminal 2 (noninverting input), there would be positive feedback. Now the output signal is fed back into the noninverting (+) input, creating a positive feedback into the operational amplifier. If you look at the diagram closely, R2 also closed the loop surrounding the operational amp. In addition to R2 in this configuration, terminal 2 has been grounded and connected to the resistor R1 in between terminal 1 and the input signal source of voltage v1. Between terminal 3 and the ground is the point from which we will take the output since there is an impedance level that is ideally zero. Due to this, voltage v0 does not depend on the impedance value of the current that is supplied to the load impedance that is connected between the ground and terminal 3.

Answer 3 :

Virtual Ground Concept, As the name suggests Virtual Ground is making a node or a connection virtually ground. By the term virtually ground means, its not physically connected to Ground but voltage at that point/node is ‘0V’ so we refer to it as Ground. This concept is used for Analysis of Operational Amplifier Circuits. It makes analysis of OP-Amp based circuits very easy.

Answer 4 :

The output of an op amp comes from a source internal to it that has an associated series resistance. Here we see the input and we see an associated series resistance that's going to become our output resistance.

The effective resistance is called the output resistance of an op amp. We looked at that back in the transistor section.

Negative feedback lowers the effective output resistance. It is low enough that for practical purposes, we will consider it to be zero.

Answer 5 :

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QUESTION 1
Ideal Op Amp characteristic are:
> It has Infinite voltage gain
> It also has Infinite Input impedance and zero output impedance
> Its gain is independent of the input
> Zero input offset voltage

QUESTION 2
Operation
> Applying a resistor across the Op Amp to cause an affect called Negative feedback.
> This effect produces a gain of amplifier in a closed loop
> Negative feedback results in the output voltage to have a opposite signal than input voltage
Characteristics
> No current flow into the input terminal
> V1=V2=0

QUESTION 3
> Virtual ground is not physically connected to the ground
> The potential difference at inverting and non-inverting terminal is always the same
> It is because of high input impedance

QUESTION 4
> To transfer all output voltage to the load.
> As the voltage drops, it will amplify the signal.

QUESTION 5
> A circuit that add several signals
> Combine voltages on inputs into a output voltage
> Output of the amp is the function of the summation of the input voltages
> Vout proportional to the sum of input voltages

QUESTION 6
> Output is in phase with the input signal
> Inverting input is connected with ground
> Feedback resistor connected between output and input terminal
> Its gain depends on passive component for stability

QUESTION 7
> Output voltage follows directly with the input voltage
> Output voltage and input voltage are equal
> A circuit which gain voltage is 1
> Op amp does not provide any amplification to the signal
> Circuit will have a very high impedance; less current off the circuit

MUHAMMAD SHAHRUL AFIQ BIN MOHAMAD RAFI ( 1728793 )

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Q1

An ideal op amp have the following characteristics :

-Ideal op amps will have infinite voltage gain.  A voltage is input into the op amp and as output, it produces the voltage amplified. An ideal op amp will produce mega-gain, practically, it will be able to produce infinite gain. It will amplify the signal infinite times over so that we can have as much gain as we'd ever need.

-Infinitely high input impedance.  This will ensure that the op amp causes no loading in the circuit. The lower the input impedance, the more current that an op amp will draw. The higher the impedance, the lower the current that an op will draw. We want high input impedance so that the op amp doesn't disturb the original circuit by pulling current from it. To do this, we need infinitely high input impedance.

-Zero output impedance.  When an op amp produces its output signal, we want the op amp to have zero voltage so that the maximum voltage will be transferred to the output load.

-Its gain is independent of input frequency , regardless of the frequency of the input signal going into the op amp, the gain that is produced will be constant and good across all frequencies.

-It has zero voltage offset,  if no voltage is applied to the inverting and noninverting input pins, the op amp will output a voltage of 0, since there is no difference at all of the voltage applied to the 2 input pins.

Q2

There are an operation amplifier and two resistors R1 and R2 inside of the inverting configuration. The second resistor, R2 is connected from terminal 3 (output terminal), back to terminal 1, which is the inverting (-) input terminal. As R2 is connected in this manner, we can apply negative feedback. In addition to R2 in this configuration, terminal 2 has been grounded and connected to the resistor R1 in between terminal 1 and the input signal source of voltage v1. Between terminal 3 and the ground is the point from which we will take the output since there is an impedance level that is ideally zero. Due to this, voltage v0 does not depend on the impedance value of the current that is supplied to the load impedance that is connected between the ground and terminal 3.

Q3

In op amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground. An active virtual ground circuit is sometimes called a rail splitter. Such a circuit uses an op-amp or some other circuit element that has gain. Since an operational amplifier has very high open-loop gain, the potential difference between its inputs tend to zero when a feedback network is implemented. This means that the output supplies the inverting input (via the feedback network) with enough voltage to reduce the potential difference between the inputs to microvolts. Thus, as far as the amplifier is working in its linear region (output not saturated, frequencies inside the range of the opamp), the voltage at the output terminal remains constant with respect to the real ground, and independent from the loads to which it may be connected. This property characterize a "virtual ground".

Q4

The output resistance of an electrical network is the measure of the opposition to current flow. An ideal op amp will have zero output resistance. When an op amp produces its output signal, we want the op amp to have zero voltage so that the maximum voltage will be transferred to the output load. Voltage is divided in a circuit according to the amount of impedance present in a circuit. Voltage drops across a component of higher impedance. In order for the voltage to drop across the output load, that load must be of greater impedance than the output of the op amp.

Q5

It is called a summing amplifier, because two signals are summed in one of the amplifier inputs.  In this case, V1 and V2 are summed in the non-inverting input. The summing of V1 and V2 is not direct.  Resistors R1 and R2 make a weighted sum and this is what makes this amplifier very useful.

Q6

In this configuration, the input voltage signal, ( VIN ) is applied directly to the non-inverting ( + ) input terminal which means that the output gain of the amplifier becomes “Positive” in value. The result of this is that the output signal is “in-phase” with the input signal. Feedback control of the non-inverting operational amplifier is achieved by applying a small part of the output voltage signal back to the inverting ( – ) input terminal via a Rƒ – R2 voltage divider network, again producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, Rin approaching infinity, as no current flows into the positive input terminal, (ideal conditions) and a low output impedance, Rout as shown below.

Q7

A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is an op-amp circuit which has a voltage gain of 1.

This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal.

An op amp circuit is a circuit with a very high input impedance. This high input impedance is the reason voltage followers are used.

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(NUR ANIS SYAKIRAH MOHD RUZI - 1729186)

QUESTION 1:

The ideal Op Amp (Operational Amplifier) is a model that has three circuit element. It is a voltage controlled voltage source with very high gain. It is modeled with differential input terminals and has a single output terminal. The characteristics of an ideal amplifier are:

1. Infinite voltage gain

2. Infinite input impedance

3. Zero output impedance

4. Infinite bandwidth

5. Zero input offset voltage

In the terms of input current the input resistance of this ideal Op Amp is infinite, which can make the current in each input to be zero. So, no current flows. In terms of voltage, the voltage gain is independent of the output current. The input voltage is the difference voltage between the two input terminals.The output voltage is measured with respect to the circuit ground node. The output will attempt to make the voltage difference between the two input terminals to be zero if it is finite.

QUESTION 2:

An operational amplifier can be in the arrangement of inverting and non-inverting amplifier. It will operate depending on the terminal at which the signal is applied, which is the fundamental negative feedback configuration . Inverting amplifier arrangement is when the input signal, V1 is applied to the inverting terminal as shown below: It is called an inverting amplifier because its voltage gain is negative. This means that if the input voltage is increasing or going positive, the output voltage will be decreasing or going negative, and vice versa. The operational amplifier is connected with feedback to produce a closed loop operation. At the inverting input terminal, the voltage for both of the terminal is the same and the gain, A is approaching ideally equivalent toward infinity in both input terminal. Since the operation amplifier has an ideal infinite input impedance now, this means that no current flows into the two input terminals and instead it will flow through R₂. So, the differential input voltage is zero as V1 = V₂ = 0 (Virtual Earth).

QUESTION 3

Virtual ground is refer to the virtual and not the real ground. For some reason we can consider it as equivalent to the real ground. The term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). But it is not physically connected to ground.  Virtual ground concept is very useful in analysis of an operational amplifier when negative feedback occur.  It can made things easy to explain and easy to make calculation. Consider an inverting op amp configuration with negative feedback. Referring to the ideal op amp, the input impedance is infinity. So, ideally no current flows through the op amp. As there is no current flowing through op amp, the current flowing through V₁ will be zero. By Ohm’s Law we could conclude that Va=0. V= I X R, as I is zero and V will also be zero.

QUESTION 4

The output resistance is the measure of the opposition to current flow. It is the ratio of change in output voltage to change in load current. An ideal constant voltage power supply should have zero output resistance so that changes in the load such as higher load currents do not cause a voltage drop at the output. The low resistance helps in reducing the noise and interference. When the supply has high impedance, high load current causes a voltage drop across this resistance and lower the output voltage. If we want all of the input current to be fully 'absorbed' by the amplifier, then ideally we need “0” input resistance in the input circuit. Thus, the input current would flow easily through the input circuit if it is in the lowest resistance.

QUESTION 5

The summing amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. It is used to add two signal voltages into a single voltage. It is one of variation of the inverting amplifier. In inverting summer, there is only one voltage signal applied to the inverting input.  the input voltages are given to the inverting terminal and non-inverting terminal is grounded, but the difference in Inverting adder circuit is it has multiple inputs at its inverting terminal.  If we connect more input terminals in parallel to the existing input terminals, we  will be end up with another op am circuit which is summing amplifier. Or if we connect more resistors to the input terminal, each input value is equal to the input of the resistor. So,  the input of the resistor can also be considered as summing amplifier. The amplifier is add the signals directly or scale them to fit some prearranged combination rule.

QUESTION 6

Non-inverting amplifier arrangement is when the input signal, V1 is applied to the non-inverting terminal as shown below: The voltage gain of non-inverting amplifier is at positive input terminal. The feedback applied at the inverting input before is now applied at the non-inverting input. The input voltage signal, V₁ is a applied directly to the non-inverting (+) input terminal, which means that the output gain of the amplifier will become positive in value.The voltage gain is always greater than one. This is in contrast with the inverting amplifier circuit, whose output gain will be negative in value. The result of output signal is “in-phase” with the input signal.  A non-inverting amplifier amplifies an input signal without inverting the signal. It also not changing the polarity of the output signal. Meaning that, if the input signal is positive, the output signal is positive.  Next, the voltage at both input is the same. If the output of the circuit remains within the supply of the amplifier, then the output voltage divided by the gain which means that there is virtually no difference between the two inputs.

QUESTION 7

A voltage follower also known as unity-gain amplifier or buffer amplifier is a op amp circuit which has a voltage gain of 1. The op amp acts as a buffer which does not provide any amplification to the signal. It is called a voltage follower because the output voltage directly follows the input voltage which means that the output voltage is the same as the input voltage. If 10V goes into the op amp as the input, then 10V will come out as the output. When a circuit has a very high input impedance, the current is dropped in the circuit. Referring to the Ohm's law, I=V/R where the greater the resistance, the less current is dropped from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load. It will not disturb the original circuit, and give the same voltage signal as output. It only draw very little power from the signal source, avoiding "loading" effects.  If a circuit has a plenty of voltage but little current, then by adding a voltage follower it will increase the current that can be supplied. The voltage follower does not amplify the voltage but it will result in the higher output current than before.

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1. The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions
An ideal op-amp is usually considered to have the following characteristics: Infinite open-loop gain G = vout / v. Infinite input impedance Rin, and so zero input current. Zero input offset voltage

2. There are two inportant characteristic of ideal inverted amplifier which is
1-No current flows into the input terminals
2-The differential input voltage is zero as V1 = V2 = 0 (Virtual Earth)

3.Virtual ground in a Op-amp is a phenomenon in which one of the input terminals will have zero terminal voltage although that terminal is not connected to ground terminal

4. In real life there is no such things as 'ideal' Op-amp. This significance of a zero output resistance plays a big role to get approximately for an Op-amp to ideal. For example you want the op-amp to be able to drive its output pin to the required voltage,  so the lower the output resistance, the better the op-amp is able to “override” the influence of any surrounding circuitry by sinking or sourcing as much (or little) current as required.

5. The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.

In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V1, V2, V3, etc. Then we can modify the original equation for the inverting amplifier to take account of these new inputs thus:

6.
In this circuit the signal is applied to the non-inverting input of the amplifier. However the feedback is taken from the output via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It is the value of these two resistors that govern the gain of the operational amplifier circuit.

The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. The calculation hinges around the fact that the voltage at both inputs is the same. This arises from the fact that the gain of the amplifier is exceedingly high. If the output of the circuit remains within the supply rails of the amplifier, then the output voltage divided by the gain means that there is virtually no difference between the two inputs.

7. Voltage Follower-

If we made the feedback resistor, Rƒ equal to zero, (Rƒ = 0), and resistor R2 equal to infinity, (R2 = ∞), then the circuit would have a fixed gain of “1” as all the output voltage would be present on the inverting input terminal (negative feedback). This would then produce a special type of the non-inverting amplifier circuit called a Voltage Follower or also called a “unity gain buffer”.

As the input signal is connected directly to the non-inverting input of the amplifier the output signal is not inverted resulting in the output voltage being equal to the input voltage, Vout = Vin. This then makes the voltage follower circuit ideal as a Unity Gain Buffer circuit because of its isolation properties.

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NUR WAHIDAH BINTI ZULKIFLI
172394

(Question 1)
Operational amplifier or op-amp is a high gain voltage amplifier. An op-amp has a differential input with a single ended output. An amplifier is considered as an ideal op-amp if it has these characteristic. The first characteristic to be considered as ideal op-amp is the open loop voltage gain (G), which is the gain without positive or negative feedback, must be infinite. Next, the input impedance is infinite. In order to get infinite input impedance, input current must be zero. After that, it has zero output impedance. It is because ideal op-amp need to act as a perfect internal voltage source without any internal resistance. So, from these characteristic, we can say that in ideal op-amp, current cannot flow in or flow out of the input terminals. Besides, the output will make the voltage difference between the input zero in a close loop.

(Question 2)
Operational amplifier can be in inverting amplifier circuit or non-inverting amplifier circuit. The difference between both circuits is where the op-amp connected. So, in inverting amplifier, op-amp is connected to the feedback. When op-amp is connected to the feedback, it will invert input to receives feedback from the output of the amplifier. It then will produce closed loop operation. The closed loop operation can be set by the ratio of two external resistor. During the inverting operational amplifier,  there will be no current flow in or out of the input terminal. Therefore, when there is no current flow, the differential input will be zero. This is because at point x or "virtual earth", the input and the feedback signal is at the same potential with positive input which is at zero volts. Hence, V1 will be equal to V2. The virtual earth then will caused the input resistance of the amplifier equal to the input value of resistor.

(Question 3)
Virtual ground or virtual earth is a node of a circuit that maintained at a steady reference potential which also called as potential at ground terminal. It is maintained without directly connected to the reference potential. For some cases, it can be considered equal to the ground which referred to the reference node. However, unlike the real ground terminal, there is possibility that the current will be restricted. It is because it is not physically connected to the ground. As it is indicates to its name, it is virtual, not real ground. This concept is used in analysis the op-amp circuit. In op-amp circuit, the virtual ground usually refers to the small signal analysis. In order to practice this concept, first, the inverting op-amp circuit need to be considered with a negative feedback. Then, by referring to the ideal op-amp parameters, the input impedance will be infinite. Hence, there will be no current flow in or out of op-amp through node Va. When there is no current, we can conclude that Ia is equal to 0. Therefore, Va also will be 0 as according to the Ohm's Law, V = IR and right now I is 0, hence V will also be 0.

(Question 4)
Zero output resistance is important when the op-amp want to drive its output pin to required voltage. It does not depend on how much load in  the output. In order to get a minimum disturbance of the signal, therefore, we need to lower the output resistance. It is to ensure that we get better op-amp in order to able to override the influence of any surrounding circuitry by sinking or sourcing as much current as required. To get an ideal op-amp, the circuit need to have zero output resistance. It implies that the output voltage is independent of the load connected to the output.

(Question 5)
Summing amplifier is another type of inverting amplifier. As indicates by its name, it enable us to add several signal together. In inverting amplifier, there is only a single voltage signal applied to it. However, it can be easily modified by combining the voltage present on several inputs in parallel so it will make a single output voltage. If we add more input resistor to the input, each of it will have the same value with the previous input resistor and will cause another summing amplifier circuit. In summing amplifier, the value of output voltage is the total of voltages input, Vout = V1+V2+V3+....From that equation, we can modified it by referring to the Ohm's Law or by applying KCL or KVL in order to find another input.

(Question 6)
The other types of operational amplifier is non-inverted amplifier. In non-inverted amplifier, the input of amplifier is connected to the ground. Before, in inverted amplifier, the feedback is applied at inverting input, but now, the input is applied at the non-inverting input. The output is in phase with the output. While the gain of the amplifier is exceedingly high, the voltage for both inputs is the same. The output voltage is divide by the gain as the output of the circuit remain the same within the amplifier. Hence, there is no difference between the two inputs. Previously, in inverted amplifier, there is no current flow and both V1 and V2 is equal is because of the junction that caused the input and V1 at same potential. Therefore, the junction which is the virtual earth act as summing point and because of that, Rf and R2 form a potential divider network across the non-inverted amplifier. The voltage gain also can determined by the ratios of R2 and Rf. The closed loop gain will be greater but less than one but if the value of Rf is zero than the gain will be equal to one.

(Question 7)
Voltage follower or also known as unity gain buffer is a type of non-inverted amplifier circuit which has a fixed voltage gain of 1 and do not amplify the incoming signal. It is called voltage follower because the output voltage directly followed the input voltage. The voltage amplifier can helped to boost available current from the circuit without increasing the voltage at the same time. The advantage of using voltage follower is it can helped to draw a very little current. An op-amp circuit has a high input impedance and  to balanced the state, it has a low output impedance. By using voltage follower, it enabled the transfer of voltage from a first circuit with a high input impedance to the second circuit with low output impedance while maintain the voltage level. It can helped preserved the voltage signal and prevents the second circuit from loading the first circuit by drawing very little power from the circuit. It is very useful at first stage.Besides, the voltage follower act as isolation buffer by isolating a circuit so that there is only a very little power of circuit is disturbed. Therefore, voltage follower can be add in the circuit when there is a circuit that capable in providing plenty of voltage but little current as it will increase the current that can be supplied. It will not change or amplify the voltage but it can increase the output current higher than the original circuit.

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QUESTION 1

An ideal design of op amp model has two input terminals, an output terminal, two power supply connections, and one or more compensation terminal. These characteristics made the model ideal as an operational amplifier.
1) Two input terminal- Referring to negative and positive terminal
2) An output terminal- Op amps are considered has a single-ended output. However, it may have inverted and non-inverted output. Most of the op amps only use the non-inverted output.
3) Two power supplies connections- There's a positive and a negative supply associated with them.
4) One or more one compensation pin- These pins are used to fine-tune the behaviour of the op amp. With 0 V on the input pins, some positive or negative output voltage will be produced. This is called the offset voltage. The typical voltage gain is 100,000. If the tiniest voltage on the inputs can cause a rather large output, these pins are required to null out this offset voltage.
5) Infinite input impedance- An ideal op-amp shouldn't be drawing any current for the inputs which means the current into terminal 1 and signal into terminal 2 are both zero. This is to say that the input impedance of an ideal op-amp is supposed to be infinite.
6) Zero output impedance
7) Infinite open loop gain, G = Vout/Vin
8) Zero input offset voltage
9) Infinite bandwith with zero phase shift and infinite slew rate.
These characteristics lead to the golden rules for op-amps. They allow you to logically deduce the operation of any op-amp circuit. The rules states that the output attempts to do whatever is necessary to make the voltage difference between the inputs zero and the inputs draw no current.

QUESTION 2 The Inverting Operational Amplifier configuration

Operation

·         We connect suitable resistor across the amplifier from the output terminal back to the inverting input terminal to both reduce and control the overall gain of the amplifier.

·         This then produces and effect known commonly as Negative Feedback, and thus produces a very stable Operational Amplifier based system.

·         This feedback connection between the output and the inverting input terminal forces the differential input voltage towards zero. This effect produces a closed loop circuit to the amplifier resulting in the gain of the amplifier

·         Then a closed-loop inverting amplifier uses negative feedback to accurately control the overall gain of the amplifier, but at a cost in the reduction of the amplifiers gain. This negative feedback results in the inverting input terminal having a different signal on it than the actual input voltage as it will be the sum of the input voltage plus the negative feedback voltage giving it the label or term of a Summing Point.
Characteristics

·         When dealing with operational amplifiers there are two very important rules to remember about inverting amplifiers, these are: “No current flows into the input terminal” and that “V1 always equals V2”.

QUESTION 3
In electronics, a virtual ground (or virtual earth) is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth, and the reference node is called "ground" or "earth" as a consequence.

QUESTION 4
Op amps have zero output impedance because of the concept of a voltage divider, which is how voltage is divided in a circuit depending on the amount of impedance present in given parts of a circuit. Once the voltage is dropped across the op amp and it does its task of amplifying the signal, the signal should get dropped across the device that the op amp should feed. For example, say we have a microphone circuit. The signals spoken into the microphone need amplification from an op amp so that they can reach a level that can drive speakers. When the signals are amplified now, they are to be dropped across the speakers. Thus, the speakers must be of greater impedance than the output of the op amp, so that the voltage signals will drop across the speakers. Thus, the op amp needs a very low output impedance, so that the amplified voltage signal drops across the speakers and not the op amp.

QUESTION 5
The Summing Amplifier ConfigurationOperations

·         The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.  in the inverting operational amplifier that the inverting amplifier has a single input voltage, (Vin) applied to the inverting input terminal.

·         If we add more input resistors to the input, each equal in value to the original input resistor, (Rin) we end up with another operational amplifier circuit called a Summing Amplifier, “summing inverter” or even a “voltage adder” circuit as shown.

Characteristics

·         The Summing Amplifier is a very flexible circuit indeed, enabling us to effectively “Add” or “Sum” (hence its name) together several individual input signals. If the inputs resistors, R₁, R₂, R₃ etc, are all equal a “unity gain inverting adder” will be made. However, if the input resistors are of different values a “scaling summing amplifier” is produced which will output a weighted sum of the input signals.

QUESTION 6
Non-inverting Operational Amplifier design.

Characteristics

·         For an ideal op-amp “No current flows into the input terminal” of the amplifier and that “V1 always equals V2”. This was because the junction of the input and feedback signal ( V1 ) are at the same potential.

·         In other words the junction is a “virtual earth” summing point. Because of this virtual earth node the resistors, Rƒ and R2 form a simple potential divider network across the non-inverting amplifier with the voltage gain of the circuit being determined by the ratios of R2 and Rƒ

Operations

Then using the formula to calculate the output voltage of a potential divider network, we can calculate the closed-loop voltage gain ( AV ) of the Non-inverting Amplifier as follows:

Then the closed loop voltage gain of a Non-inverting Operational Amplifier will be given as:

We can see from the equation above, that the overall closed-loop gain of a non-inverting amplifier will always be greater but never less than one (unity), it is positive in nature and is determined by the ratio of the values of Rƒ and R2.

If the value of the feedback resistor Rƒ is zero, the gain of the amplifier will be exactly equal to one (unity). If resistor R2 is zero the gain will approach infinity, but in practice it will be limited to the operational amplifiers open-loop differential gain, ( AO ).

We can easily convert an inverting operational amplifier configuration into a non-inverting amplifier configuration by simply changing the input connections as shown

QUESTION 7
If we made the feedback resistor, Rƒ equal to zero, (Rƒ = 0), and resistor R2 equal to infinity, (R2 = ∞), then the circuit would have a fixed gain of “1” as all the output voltage would be present on the inverting input terminal (negative feedback). This would then produce a special type of the non-inverting amplifier circuit called a Voltage Follower or also called a “unity gain buffer”.

The advantage of the unity gain voltage follower is that it can be used when impedance matching or circuit isolation is more important than amplification as it maintains the signal voltage. The input impedance of the voltage follower circuit is very high, typically above 1MΩ as it is equal to that of the operational amplifiers input resistance times its gain ( Rin x AO ). Also its output impedance is very low since an ideal op-amp condition is assumed.

Maisarah binti Mohamad Sattar (1728650)

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- ZIEZI EZWANIE BINTI ZAINOL AFANDI

- 1725058

QUESTION 1

Op-Amps are linear devices that have all the properties required for nearly ideal DC amplification. The circuit can perform many mathematical operations that is why it is called operational amplifier. Op-Amps are one of the basic building blocks of analog circuits, since any electronic circuit can be constructed by using op-amp.

Ideal op-amp can be identified with the following characteristics:

a) Infinite open-loop gain (Avo)

Op-Amp's main function is to amplify the input signal therefore the more open loop gain is the better.

b) Infinite input impedance

The input impedance(Zin) is assumed to be infinite to prevent current flowing into the amplifier.

c)Zero output impedance

Current will be supplied enough to the load with zero internal resistance.

d)Infinite bandwith

Ideal Op-Amp can amplify any frequency signal from DC to the highest AC frequencies.

e)Zero input offset voltage(ie. exactly zero out if zero in)

The implication of this model in terms of input currents is there is no current flowing into the amplifier as the input impedance is infinite. Meanwhile, input offset voltage is zero to make sure the ouput is zero.

QUESTION 2

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Based on the circuit above, the operational amplifier is connected with feedback to produce a closed loop operation.  The characteristics for inverting amplifiers are no current flows into the input terminals and the differential input voltage is zero as V1=V2=0 (Virtual Earth).

QUESTION 3

Virtual ground is where the node has voltage almost equal to ground voltage (0V). However, it is not physically connected to the ground. It is useful in Op-Amp circuits analysis and make calculations a lot easier.

QUESTION 4

The reason why we have zero output resistance is because we want to transfer all the output voltage to the load. Examples of load are a speaker, hard disk motor and digital circuits. If the output resistance is not zero, there will be voltage division which will make the load receive weak input.

QUESTION 5

Ideal Summing Amplifier which is also called adder as is a circuit where we can add several signals together. We can change the gain or add another input without messing with the gains of  other inputs. The operation of this ideal summing amplifier is based on the circuit below.

https://padlet-uploads.storage.googleapis.com/315591657/04ce8b3ca4a5fde3a9b89b1c70de3df1/uy.png

Va, Vb and Vc are input signals. These input signals are given to the inverting terminal of the operational amplifier using input resistors like Ra, Rb and Rc. Rf is feedback resistor and RL is load resistor. We can use KCL to get equation : If=Ia+Ib+Ic. After some derivations, we get V0= -(Va+Vb+Vc).

The characteristic for ideal summing amplifier is when there more than one input voltage ends up as one output voltage.

QUESTION 6

Op-Amp is identified as non-inverting format when the output is in phase with the input signal. In this circuit the signal is applied to the non-inverting input of the op-amp. The signal of the output is not inverted when compared to the input. The feedback is taken from the output through a resistor to the inverting input of the op-amp. Meanwhile, another resistor is taken to ground. It has to be applied to the inverting input as it is negative feedback.

Gain in non-inverting amplifier is :

Vout/Vin = Av = 1 + R2/R1

QUESTION 7

The properties of voltage follower are voltage follower will result voltage gain equals to 1, input resistance of voltage follower is infinity and the output resistance is low. The advantage of using voltage follower is it is used to boost the current available from a circuit without increasing the voltage at the same time. Second, the voltage follower does not amplify the voltage but the output current

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DISCUSSION ANSWERS { NUR ALYAA SYAZWANI MOHD ZAIDI - 1725810 }

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DISCUSSION ANSWERS { NUR ALYAA SYAZWANI MOHD ZAIDI - 1725810 }

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§  Question   1

The ideal Op-Amp Model is in which it includes these characteristics; infinite input impedance, zero output impedance, infinite voltage gain, zero input offset voltage. An operational amplifier or Op-Amp is said to be ideal if it has infinite input resistance and zero input current due to the infinite input impedance and zero output impedance.  This differential amplifier with a single-ended output is commonly known as a high voltage gain amplifier at all frequencies, whereby the internal voltage gain of op-amp decreases at higher frequencies. Therefore, with 0-V on the input pins, some output voltage may result. This is called the offset voltage with either positive or negative polarity. An ideal op amp also includes the negative feedback whereby it is the return of a portion of the output signal to the input signal (out-of-phase). Usually, the infinite voltage gain closed loop (ACL) has a feedback, and the infinite voltage gain open loop (AOL) has no feedback.

§  Question  2

The basic amplifier configurations are inverting amplifier and non-inverting amplifier. The characteristics of an ideal inverting amplifier is when RF  provides a portion of the output back to the input which is called negative feedback. The input signal is applied to the inverting input, resulting to output being reversed.  The circuit operation for the ideal inverting amplifier is when due to negative input remains at ground potential (0-V), it is referred to as virtual ground. Because of the feedback loop, it results to voltage gain in an inverting amplifier according to the formula: Av = -RF / R₁

§  Question   3

Ideally the gain of op-amp is infinite. The virtual ground or virtual earth or usually called as virtual short is that the potential at inverting and non-inverting terminal is always same if when any of the input two terminals is grounded, the second terminal will also have ground potential. This happens because of very high input impedance of op-amp, no current flow in both the terminal of op-amp so no voltage drop takes place between these two terminals, resulting to both terminals to have same potential due to virtual ground.

§  Question   4

The output resistance comes from internal source that has an associated with series resistance. The effective resistance resulted is called the output resistance. The negative feedback lowers output resistance, which is usually low enough for practical purposes that it is considered to be zero. The ideal op-amp has infinite input impedance and zero output impedance because it's easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series). The low resistance helps in reducing the noise and disturbance. In order to have the input current to fully enter the amplifier, the input resistance must decrease to ensure it flows easily through the input circuit.

§  Question   5

The Summing Amplifier is another type of operational amplifier circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage.In the inverting operational amplifier that the inverting amplifier has a single input voltage, (Vin) applied to the inverting input terminal. If we add more input resistors to the input, each equal in value to the original input resistor, (Rin) we end up with another operational amplifier circuit called a Summing Amplifier, “summing inverter” or even a “voltage adder” circuit as shown above. The easiest way to characterize (characteristic) of summing amplifier is when the input voltage is present to be two or more resulting to an output voltage. In this simple summing amplifier circuit, the output voltage, ( Vout ) now becomes proportional to the sum of the input voltages, V₁, V₂, V₃, etc.

§  Question   6

In which the basic amplifier configurations has non-inverting amplifier and inverting amplifier, here are several characteristics and identification to recognize the non-inverting amplifier. First of all for the characteristics, it is typical if the signal is applied to the inverting negative input, the output will be inverted. Meanwhile, if the signal is applied to the inverting positive input, the output will not be inverted. As we know, the op amp open loop gain is extremely high. Therefore, the output voltage will only responds to the difference in potential between its two inputs. Output voltage swing also will be limited to within 103 V of the supply voltage. Proceeding to the circuit operation, as the input pins on an op-amp are essentially open circuits, no voltage drops across RB.  This is because the input impedance infinite, therefore the voltage drop is 0-V at RB unless it is stated that the value of RB can be ignored. Feedback resistor or RF and R₁ wil form a voltage divider across output voltage and find the voltage gain using Av = (RF/ R₁) + 1.

§  Question   7

A voltage follower (also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier) is a op-amp circuit which has a voltage gain of 1. This means that the op amp does not provide any amplification to the signal. The reason it is called a voltage follower is because the output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Thus, for example, if 10V goes into the op amp as input, 10V comes out as output. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. The advantages of using this voltage follower circuit is so that when a circuit has a very high input impedance, very little current is drawn from the circuit. If you know ohm's law, you know that current, I=V/R. Thus, the greater the resistance, the less current is drawn from a power source. Thus, the power of the circuit isn't affected when current is feeding a high impedance load. Other than that, the reason voltage followers are used because of their importance in voltage divider circuits. This again deals with ohm's law. According to ohm's law, voltage= current x resistance (V=IR).

In a circuit, voltage divides up or is allocated according to the resistance or impedance of components. Because an op amp has a very high input impedance, the majority of voltage will fall across it, (since it's so high impedance). So it's very valuable when used in a voltage divider circuit because strategically doing so can allow a designer to supply sufficient voltage to a load.