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MUHAMMAD ZULKARNAIN BIN ZAKARIA (1723395)

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 because the initial current is zero due to the infinite resistance. 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. It provide the same voltage at the output  and the voltage at the input.

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1. Ideal op amps have infinite voltage gain, infinitely high impedance, zero output impedance, its gain is independent of input frequency.The implications of this ideal model is zero input current and zero input offset voltage.

2. Inverting amplifier is one in which the output is exactly 180 degree out of phase with respect to input. Output is an inverted amplified version of input in terms of phase. The characteristics of the inverting amplifier is no current flow into input terminals and the differential input voltage is zero.

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

4. The significance of a zero output resistance is that it can supply a lot of current from them and carry large loads passing it.

5. Ideal summing amplifier combines the voltages present on two or more inputs into a single output voltages.The summing amplifier able to take almost unlimited number of inputs and none of one input should appear on another input.

6.  Non-inverting circuit has the input impedance increased to infinity and the feedback impedance reduced to zero. The output is connected directly back to the negative inverting input so the feedback is 100% and input voltage is exactly equal to output voltage giving it a fixed gain of .
The input impedance is infinite and also no current flows through the feedback loop so any value of resistance may be placed in the feedback loop without affecting the characteristics of the circuit as no voltage is dissipated across it, zero current flows, zero voltage drop, zero power loss.

7. A voltage follower 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. It is the safe and easy 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.

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Muhammad amirul farhan bin amran 1816013                    1. The ideal op-amp model includes infinite input impedence so that the little current is required to produce voltage. Besides, infinite loop gain so that voltage differential on the two input terminals will result in an infinite voltage on the output

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Muhammad amirul farhan bin amran 1816013                    1. The ideal op-amp model includes infinite input impedence so that the little current is required to produce voltage. Besides, infinite loop gain so that voltage differential on the two input terminals will result in an infinite voltage on the output

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2. The operational amplifier is connected with the feedback to produce a closed loop operation. Remember about inverting amplifiers, no current flows into the input terminal and that v1 always equal to v2. One of the main features of the inverting amplifier circuit is the overall gain that it produces. The voltage gain, Av is actually the output voltage divided by the input voltage. It is the number of times the output voltage is larger than the input voltage.

3. Virtual ground for some purposes we can consider it as equivalent to ground. In op-amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage ( 0v)

4. An ideal constant voltage power supply should have zero output impedence that charges in the load such as higher load currents do not cause a voltage drop at the output.

5. The term summing amplifier is also named as adder, which is used to add two signal voltages. The circuit of the voltage adder is so simple to construct and it enables to add many signals together. The summing amplifier is a very flexible circuit, enabling us to effectively “sum” several individual input signals. If the input resistors, R1, R2, R3 etc, are equal a “unity gain inverting adder” will be made. However, if the input resistors are of different values a “scalling summing amplifier” is produced which will output a weighed sum of the input signals

6. The op-amp non-inverting amplifier circuit provides a high input impedence along with all the advantages gained from using an operational amplifier is easy to determine. The calculations hinge around 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. A voltage follower is also known as a unity gain amplifier, a voltage buffer, or isolation amplifier. In a voltage follower circuit, the output voltage is equal to the input voltage; thus, it has a gain of one (unity) and does not amplify the incoming signal. The voltage follower allows us to move from one circuit to another and maintain the voltage level. It preserves the voltage source signal. This is why its also called a buffer or isolation amplifier

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

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Nurul Shafiqah Binti Haja Salim (1815960)

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Nurul Shafiqah Binti Haja Salim (1815960)

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Discussion Questions

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

Op-Amp is an analog integrated circuit that can perform many mathematical operations. It has two input terminals and one output terminal. The input terminals are called as inverting input terminal and non-inverting input terminal. Op-Amp also need power supply to operate. Both positive and negative power supply are used simultaneously. Input resistance of Op-Amp is infinity while output resistance is 0. At the close-loop operation, inverting input terminal is virtual ground. There should be no change in output voltage for any amount of voltage applied between those two shorted inputs and ground.

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

Inverting amplifier makes a 180 degree phase difference between input and output signals. The benefit of this amplifier is that its gain does not depend on the active component parameter but it depends on the passive component. Therefore, the gain of the amplifier is highly stable. According to Miller’s theorem, if the voltage gain of the amplifier is infinite then this close-loop amplifier’s inverting input terminal acts as a virtual ground where the potential of this point is zero with respect to ground but actually it does not connect to the ground physically.

3. What is the concept of virtual ground?

A virtual ground is a node of a circuit that is maintained at a steady reference potential without connected directly to the reference potential. In some cases the reference potential is considered to be that of the surface of the earth where the reference node is called "ground" or "earth" as a consequence. This concept helps circuit analysis in operational amplifier and other circuits as well as provides useful practical circuit effects that would be difficult to achieve in any other ways. A node may have any value of current or voltage but physical implementations of a virtual ground will have limitations of current handling ability and a non-zero impedance which may have practical side effects.

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

A low resistance means that the circuit draws or provides more power on the signal. Input resistance must be higher than output resistance. Input is only capable to provide power to output. If input resistance is lower than output resistance, input voltage will be dropped. Zero output resistance can provide the correct voltage level on the signal and the signal will be read correctly. Low impedance in a voltage source is usually preferred because it helps to keep out the noise out of the circuit and maintain a stable output voltage.

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

The output of the amplifier is the function of summation of the input voltages. The circuit can be done based on virtual ground or Kirchhoff current low. A summing amplifier sums several weighted voltage. Output is inverted.

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

The input and output signals are in the same phase. The benefit of this amplifier is that its gain does not depend on the active component parameter but passive component parameter which cause the gain of amplifier is infinite. If the voltage gain of amplifier is infinite, the close-loop amplifier inverting inverting input terminal acts as virtual ground. The potential of this point is zero with respect to the ground but physically not connected to the ground. Assume that no current enters the input terminal since the ideal op-amp input resistance is infinite.

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

In a voltage follower the output voltage is equal to the input voltage. The advantage of this circuit is that the op-amp can provide current and power gain. It also has very large input resistance and very small output resistance which can be used as an impedance transformer or buffer circuit. The op-amp draws almost no current from the input. It provides low output impedance to any circuit using the output of the follower where the output will not drop under load.

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SHAHRUL NIZAM 1719379

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

- Op-Amp is an analog devices in electronics used to gain in terms of voltage or current of the circuit. it has two input signal and a single output signal also has positive and negative terminal of power supply connected to it. The output is proportional to gap of the two input signal. the gap produces the high resistance which results to the higher voltage. the application of this devices is usually used to operate feedback function.

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

- the design of inverting op-amp circuit makes the amplifier unstable and hard to control due to the smallest of input signal. it can be afforded by losing some of this high gain by connecting a proper resistor across the amplifier from the output terminal back to the inverting input terminal to reduce and control the overall gain of the amplifier. This process is negative feedback that produces a very stable op-amp.

3. What is the concept of virtual ground?

-  Virtual ground means it is not physically connected to ground but voltage at that point is 0V. In ideal Op-Amp parameters, the input Impedance is infinite. So, no current flows through Op-amp. As there is no current flowing through Op-amp, Current flowing through node will be 0A, therefore the voltage will be 0V.

4. What is the significance of a zero output resistance?
-The configuration of zero output resistant in the case of virtual ground will occur the buffer which means the input voltage equals to output voltage without multiplication to the ratio of resistor.

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

- The resistances of input signal will determine the output signal that we call as feedback resistance. the deference resistance of input of resistors will produce the ratio between them that will be affected to the feedback resistant.

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

- The voltage source(input voltage) is connected to the positive sign of amplifier while the other side is connected to the inverting terminal (positive sign) of amplifier. From the analysis of the circuit, output voltage equals to the ratio of resistors that we had added and multiplied by the input voltage.

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

Input signal is applied directly to non-inverting input of amplifier. Then the output signal will not inverted and thus the output voltage is the same as input voltage, Vout = Vin.

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SHAHRUL NIZAM 1719379

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

Op-Amp is an analog devices in electronics used to gain in terms of voltage or current of the circuit. it has two input signal and a single output signal also has positive and negative terminal of power supply connected to it. The output is proportional to gap of the two input signal. the gap produces the high resistance which results to the higher voltage. the application of this devices is usually used to operate feedback function.

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

the design of inverting op-amp circuit makes the amplifier unstable and hard to control due to the smallest of input signal. it can be afforded by losing some of this high gain by connecting a proper resistor across the amplifier from the output terminal back to the inverting input terminal to reduce and control the overall gain of the amplifier. This process is negative feedback that produces a very stable op-amp.

3. What is the concept of virtual ground?

Virtual ground means it is not physically connected to ground but voltage at that point is 0V. In ideal Op-Amp parameters, the input Impedance is infinite. So, no current flows through Op-amp. As there is no current flowing through Op-amp, Current flowing through node will be 0A, therefore the voltage will be 0V.

4. What is the significance of a zero output resistance?
-The configuration of zero output resistant in the case of virtual ground will occur the buffer which means the input voltage equals to output voltage without multiplication to the ratio of resistor.

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

The resistances of input signal will determine the output signal that we call as feedback resistance. the deference resistance of input of resistors will produce the ratio between them that will be affected to the feedback resistant.

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

The voltage source(input voltage) is connected to the positive sign of amplifier while the otherside is connected to the inverting terminal (positive sign) of amplifier. From the analysis of the circuit, output voltage equals to the ratio of rasistors that we had added and multiplied by the input voltage.

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

In a voltage follower the output voltage is equal to the input voltage. The advantage of this circuit is that the op-amp can provide current and power gain. It also has very large input resistance and very small output resistance which can be used as an impedance transformer or buffer circuit. The op-amp draws almost no current from the input. It provides low output impedance to any circuit using the output of the follower where the output will not drop under load.

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

An ideal op amp will have infinite voltage gain and infinitely high input impedance. It also will have zero output impedance. In an ideal op amp, the gain that the op amp produces will be independent of frequency. If no voltage is applied to the inverting and non inverting 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.

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

The input signal is applied through resistor R1 to the inverting op amp input. Resistor RF is the feedback resistor which connects from the output to the inverting input. The circuit is called an inverting amplifier because its voltage gain is negative. If the input voltage is increasing or going positive, the output voltage will be decreasing or going negative, and vice versa.

3. What is the concept of virtual ground?

Virtual ground means that the voltage at that particular node is almost equal to ground voltage. It is not physically connected to ground. The voltage is approximately zero and not able to sink infinite current.

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

The significance of zero output resistance is means it can supply as much current as necessary to the load. The output resistance of the ideal operational amplifier is assumed to be zero. So, it supply maximum current to the load.

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

Ideal summing amplifier is used to add two signal voltages. The circuit of the voltage adder is so simple to construct and it enables to add many signals together. This kind of amplifiers is used in a wide range of electronic circuits. For summing amplifier, it is possible to apply more than one input single to an inverting amplifier. This circuit will then add all this input signals to produce at the input. The input resistance is infinity and the input current is 0.

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

In the non-inverting circuit, the input impedance Rin has increased to infinity and the feedback impedance Rƒ reduced to zero. The output is connected directly back to the negative inverting input so the feedback is 100% and Vin is exactly equal to Vout giving it a fixed gain of 1 or unity.

the input impedance is infinite (ideal op-amp) and also no current flows through the feedback loop so any value of resistance may be placed in the feedback loop without affecting the characteristics of the circuit as no voltage is dissipated across it, zero current flows, zero voltage drop, zero power loss.

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

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. The output voltage directly follows the input voltage, meaning the output voltage is the same as the input voltage. Voltage follower has three unique characteristics which are extremely high input impedance, extremely low output impedance and unity transmission gain. Therefore, an ideal circuit device for use as a buffer amplifier.

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1. Ideal op-amp model has infinite open loop voltage gain,infinite input impedance,zero output impedence and infinite bandwidth.The input currents and voltages will be zero.

2.  An ideal 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 the differential input is zero.

3. Virtual ground refers to a circuit element not directly connected to ground, held at a reference voltage. This reference voltage need not be the same voltage as ground either. As long as signal voltage are compared to this virtual ground,filtering or modification of the oscillating signals can be handled just fine as they only go negative relative to the virtual ground.

4. The significance of zero output resistance is that 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.

5. Ideal summing amplifier is another type of op amp circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. The operation is when more input resistors are added to the input terminal, each equal in value to the original input resistor. Ideal summing amplifier should be able to take almost unlimited number of inputs and none of one input should appear at another input.

6.  Input voltage is applied to the non-inverting Op-Amp input. A voltage divider consisting of feedback resistors and another resistor connects from the output node to the inverting input. The circuit is called a non-inverting amplifier because its voltage gain is positive. This means that if the input voltage is increasing or going positive, the output voltage will also be increasing or going positive.

7. Voltage follower is a special type of non-inverting amplifier circuit produced when a circuit have a fixed gain of 1 as all the output voltage would be present on the inverting input terminal. The advantages of voltage follower is that it can be used when impedance matching or circuit isolation is more than amplification as it mantains the signal voltage.

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Mohammad Azfar Zikri Bin Azhar [1818985]

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Mohammad Azfar Zikri Bin Azhar [1818985]

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1) The ideal Op-Amp model have a few characteristics which are infinite voltage gain and input impedance, zero output impedance, infinite bandwidth and zero input offset voltage. Most op amps use dual power supplies.
The implications of this ideal model in terms of input currents and voltages is The output attempts to do whatever is necessary to make the voltage difference between the inputs zero and the input draw no current.
2)  The input signal is applied through resistor to the inverting op amp input. The feedback resistor which connects from the output to the inverting input. If the input voltage is increasing or going positive, the output voltage will be decreasing or going negative because the voltage gain is negative.
3)  Making a node or a connection virtually ground and its not physically connected to Ground but voltage at that point/node is zero so we refer to it as Ground.
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.
5) Combining the voltages present on two or more inputs into a single output voltage. the output voltage now becomes proportional to the sum of the input voltages.
The summing point is connected to the inverting input of the op-amp. The circuit will produce the negative sum of any number of input voltages.
6)  The input voltage is applied to the non-inverting op amp input. A voltage divider consisting of resistors RF and R connects from the output node to the inverting input. The circuit is called a non-inverting ampliﬁer because its voltage gain is positive. This means that if the input voltage is increasing or going positive, the output voltage will also be increasing or going positive
7) A unity-gain non-inverting ampliﬁer. Compared to the non-inverting ampliﬁer ,the feedback resistor RF is replaced by a short circuit and resistor R is omitted. Because the output node is connected directly to the inverting input instead of through a voltage divider, the circuit is said to have 100% feedback. Therefore, the circuit has unity voltage gain. The voltage follower is often used to isolate a low resistance load from a high output resistance source. That is, the voltage follower supplies the current to drive the load while drawing no current from the input circuit

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1.Ideal op-amp model has infinite open loop voltage gain,infinite input impedance,zero output impedence and infinite bandwidth.The input currents and voltages will be zero.

2.An ideal inverting amplifier,the input signal is applied through resistor to the inverting Op-Amp input.The feedback resistor connects from the output to the inverting input.The circuit is called an inverting amplifier because its voltage gain is negative. So the input voltage is increasing,the output voltage will decreasing and vice versa.

3.The virtual ground means when the voltage at particular nodes is equal to ground voltage=0 V.But it is not actually grounded.

4.The significance of zero output resistance is the load will not cause the voltage to drop at the output and thus the load can get sufficient power to operate properly.

5.The output of the amplifier is the funtion of the summation of the input voltages. To simplify the analysis ,only three input signals are arbitrarily selected.The close-loop amplifier inverting input terminal act as virtual ground.The input resistance is infinity while the input current is 0.

6.The op amp non-inverting amplifier circuit provides a high input impedence and the advantage gained from using an operational amplifier. Even the basic non-inverting amplifier op amp circuit requires the same number components as it inverting counterpart,its find uses in application where the high input impedence of it importance.

7.The voltage follower of buffer amplifier circuit,where the output is simply equal to the input.The voltage follower does not need any external components. So,the advantage of this circuit is that the op amp can provide current and power gain. It also provides low output impedence to any circuit using the output of the follower, meaning that the output will not drop under load.

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

- 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. An Operational Amplifier, or op-amp for short, is fundamentally a voltage amplifying device designed to be used with external feedback components such as resistors and capacitors between its output and input terminals. These feedback components determine the resulting function or “operation” of the amplifier and by virtue of the different feedback configurations whether resistive, capacitive or both, the amplifier can perform a variety of different operations, giving rise to its name of “Operational Amplifier

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

- inverting amplifier:

·Inverting amplifier is one in which the output is exactly 180 degree out of phase with respect to input(i.e. if you apply a positive voltage, output will be negative).

· Output is an inverted(in terms of phase) amplified version of input.

· Assuming the op-amp is ideal and applying the concept of virtual short at the input terminals of op-amp, the voltage at the inverting terminal is equal to non inverting terminal.

3. What is the  concept of virtual ground?

- 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.

-The virtual ground concept aids circuit analysis in operational amplifier and other circuits and provides useful practical circuit effects that would be difficult to achieve in other ways.

-In circuit theory, a node may have any value of current or voltage but physical implementations of a virtual ground will have limitations of current handling ability and a non-zero impedance which may have practical side effects.

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

It  means that the output voltage is independent of output current. Real, physical op-amps only approximate this ideal and have very large input impedance and very low output impedance.

A high load impedance also means there won't be much current, which also means less power. The ideal op-amp has infinite input impedance and zero output impedance because it's easy to make the input impedance lower by putting a resistor in parallel or the source impedance higher by putting a resistor in series.

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

- 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

- Summing amplifier is a versatile device, used to combine the signals. These amplifiers add the signals directly or scale them to fit some prearranged combination rule.

· These amplifiers are used in an audio mixer to add different signals with equal gains

·There are various resistors are used at the input of the summing amplifier to give a weighted sum. This can be used to change a binary number to a voltage in an AC (digital to analog converter)

·This amplifier is used to apply a DC offset voltage with an AC signal voltage. This process can be done in an LED modulation circuit to maintain the LED in its linear operating range.

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

- The op amp non-inverting amplifier circuit provides a high input impedance along with all the advantages gained from using an operational amplifier.

Although the basic non-inverting op amp circuit requires the same number components as its inverting counterpart, it finds uses in applications where the high input impedance is of importance.The basic circuit is relatively straightforward.

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

- A voltage follower is also known as a unity gain amplifier, a voltage buffer, or an isolation amplifier. In a voltage follower circuit, the output voltage is equal to the input voltage; thus, it has a gain of one (unity) and does not amplify the incoming signal. The voltage follower does not need any external components

- the advantages is it has a very high input impedance, which means that they don’t suck in much current (ideally, none) at the inputs. Op amps also have a very low output impedance. One application where this is useful is in a voltage divider. In a voltage divider it’s possible that the impedance load (Ro) can vary quite a bit.

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Discussion Questions

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 terminal characteristics of the ideal op amp satisfy four conditions which are the current in each input lead is zero, the output voltage is independent of the output current, the voltage gain A is independent of frequency and the voltage gain A is very large, approaching infinity in the limit. The first condition implies that the resistance seen looking into both input terminals is infinite. The second implies that the voltage gain is independent of the output current. This is equivalent to the condition that the output resistance is zero. The third implies that the bandwidth is infinite. The fourth implies that the difference voltage between the two input terminals must approach zero if the output voltage is finite.

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 the differential input is zero.

3. The circuit is a special case of an inverting amplifier where the input resistor is replaced with a short circuit. Because the v− terminal is a virtual ground, the input resistance is zero. The output resistance is also zero. Because i1 +iF = 0 and vO = iFRF .

4. 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). It's not so easy to go the other way; you 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.

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. Although, there are many ways to make a summer, this one is nice because it keeps the interaction between inputs at a minimum. 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.It need the opposite polarity, put an inverting stage before or after the summer.

6. The input voltage vI is applied to the non-inverting op amp input. A voltage divider consisting of resistors RF and R1 connects from the output node to the inverting input. The circuit is called a non-inverting amplifier because its voltage gain is positive. This means that if the input voltage is increasing or going positive, the output voltage will also be increasing or going positive. If the circuit diagrams of the inverting and the non-inverting amplifiers are compared, it can be seen that the circuits are the same if vI = 0. Thus the only difference between the two circuits is the node at which the input voltage is applied.

7. The voltage follower or unity-gain buffer is a unity-gain non-inverting amplifier. Compared to the non-inverting amplifier of the feedback resistor RF is replaced by a short circuit and resistor R1 is omitted. Because the output node is connected directly to the inverting input instead of through a voltage divider, the circuit is said to have 100% feedback. Because v+ = v−, it follows that vO = vI . Therefore, the circuit has unity voltage gain. The voltage follower is often used to isolate a low resistance load from a high output resistance source. That is, the voltage follower supplies the current to drive the load while drawing no current from the input circuit.

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

An ideal Op-Amp is a device with certain special characteristics such as infinite open-loop gain, infinite input resistance, zero output resistance, infinite bandwidth and zero offset.

The implication to this ideal model results with the following two “golden rules” of op amps:

i. The output attempts to do whatever is necessary to make the voltage difference between the inputs zero.

ii. The input draws no current.

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

Inverting amplifier is one in which the output is exactly 180 degree out of phase with respect to input.

The circuit 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.

3. What is the concept of virtual ground?

Virtual ground refers to a circuit element not directly connected to ground, held at a reference voltage. This reference voltage need not be the same voltage as ground either. As long as signal voltage are compared to this virtual ground, filtering or modification of the oscillating signals can be handled just fine as they only go negative relative to the virtual ground.

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

This means that the output voltage is independent of output current.

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

The summing amplifier is a useful circuit lets you to add several signals together. The circuit has multiple inputs which are summed to create the output. Each input is an ideal voltage source. This circuit forms an output which is the sum of gains times input voltages.

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

In this circuit the signal is applied to the non-inverting input of the op-amp. In this way the signal at the output is not inverted when compared to the input. However the feedback is taken from the output of the op-amp through a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It has to be applied to the inverting input as it is negative feedback. It is the value of these two resistors that determine the gain of the operational amplifier circuit as they determine the level of feedback. The voltage at both inputs is the same.

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

A voltage follower 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. 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. Another advantage of the voltage follower is

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MUHAMMAD IMAN MUSTAQQIM BIN BORHANODDIN (1810089 )

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MUHAMMAD IMAN MUSTAQQIM BIN BORHANODDIN (1810089 )

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Q1) Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages.

An ideal op amp is an op amp that has perfect conditions so it can function as an op amp with 100% efficiency. Ideal op amp has infinite voltage gain, zero output impedance, the gain is independent of input frequency, infinite high impedance, it has zero voltage offset. And the implication in terms of input currents and voltages;

1. Gain bandwidth product is infinity

2. Infinite voltage gain

3. Infinite input impedance

4. Zero output impedance

5. Zero input offset voltage

Q2) Describe the operation and characteristics of the ideal inverting amplifier.

Op Amp 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. It inverts input to receive feedback from the output of the amplifier. Then it will produce closed loop operation. During the inverting operational amplifier, there will be no current flow in or out of the input terminal. So, when there is no current flow, the differential input will be zero. This is because at virtual earth, the input and the feedback signal is at the same potential with positive input which is at 0V. 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.

Q3) What is the concept of virtual ground?

Virtual ground is refer to the virtual one and not the real ground. But we can consider it as equivalent to the real ground with some reasons. The virtual ground means that the voltage at that particular node is almost equal to ground voltage. But it is not physically connected to ground.  Virtual ground concept is very useful in analysis of an operational amplifier when negative feedback occur. We can easily explain and make calculation. Consider an inverting op amp configuration with negative feedback. Based on the ideal op amp, the input impedance is infinity. So, no current flows through the op amp and 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.

Q4) What is the significance of a zero output resistance?

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 by putting a resistor in parallel or the
source impedance higher by putting a resistor in series. The low resistance can
reduce 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.

Q5) Describe the operation  and characteristics of the ideal summing amplifier

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 . By referring to the Ohm's Law or by applying KCL or KVL,we can find another input.

Q6) Describe the operation and characteristics of the ideal non inverting amplifier

In the non-inverting, the output will be the same phase as the input. Then we have a portion that go back to the inverting input. 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 weaken the signal. This idea of negative feedback is that the feedback opposes the original input signal. Since the op amp ideally has infinite input resistance, no current flows into the input. This effectively has infinite input impedance. The input voltage will go across this resistance.

Q7) Describe the voltage follower. what are the advantages of using this circuit.

A voltage follower is an op amp circuit which has a voltage gain of 1. It does not provide any amplification to the signal and the output voltage directly follows the input voltage. So V₀=Vi. An op amp circuit is a circuit with very high input impedance. The advantage is that its input resistance is very large and output resistance is very small, so that it can be used as an impedance transformer or buffer circuit. The impedance transformer or buffer is used to avoid the loading effect on the circuit. This is the reason why the 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. But it has limited drive capability

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Rashidah Syakirah Bt Mohd Saidi (1818916)

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Rashidah Syakirah Bt Mohd Saidi (1818916)

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1. The ideal Op-Amp model is when the input current is zero. So, the both input impedance will be infinite. When the input impedance is high, the op amp will not disturb the original circuit by pulling current from the circuit. The ideal Op-amp must have zero impedance in the output so that the maximum voltage will be transferred to the output load. Voltage is divided in the circuit according the amount of impedance present in the circuit. In order for the voltage to drop across the output load, the impedance must be higher than the output of the op-amp.

2.  An inverting amplifier is an arrangement of op-amp when the input signal, is applied to the negative terminal. It is called an inverting amplifier because the voltage gain is negative. For example, if the input voltage is low, the output voltage produced will be high and vice versa. The op-amp is connected to the feedback to produce a closed loop operation. The voltage of both input terminal is the same and since the input impedance is infinity, no current flow into the both input terminals and instead it will flow through the resistor. So, both input voltage is zero.

3. The virtual ground means when the voltage at that particular node is almost equal to ground voltage which is 0 V but it is not actually grounded. It can be when we providing a negative feedback to the op amp.

4.  The significance of zero output resistance is that 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.

5. The operation of summing amplifier is to combine the voltages present on two or more inputs into a single output voltage.

6.   In non-inverting Op-Amp configuration, the input is applied at the non-inverting terminal of the op-amp and feedback is applied from the output the inverting end of the op-amp. In this configuration, the input and output voltages are in phase with each other.

The input impedance of this configuration is ideally infinite and practically it is very high.

7.  A voltage follower is when the output voltage is equal to the input voltage. The advantages of this circuit are the op-amp can provide current and power gain. It also providing a large input resistance and very small output resistance that can be used as a buffer circuit.

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1) Ideal om-amp model have infinite input impedance and zero output impedance. The implication of this ideal model is to make offset voltage when input voltage is 0V on the input pins.
2) As the open loop DC gain of an operational amplifier is extremely high we can afford to lose some of this high gain by connecting a suitable resistor across the amplifier from the output terminal back to the inverting input terminal to reduce and control the overall gain of the amplifier known as Negative Feedback which we feed it back to the negative terminal of the op-amp using an external Feedback Resistor. This feedback connection between the output and the inverting input terminal forces the differential input voltage towards zero producing a closed loop circuit. A closed-loop inverting amplifier uses negative feedback to control the overall gain of the amplifier results in the inverting input terminal having a different signal on it. The separation of the real input signal from the inverting input must be made by using an Input Resistor. As we are not using the positive non-inverting input this is connected to a common ground or zero voltage terminal but the effect of this closed loop feedback circuit results in the voltage potential at the inverting input being equal to that at the non-inverting input producing a Virtual Earth summing point because it will be at the same potential as the grounded reference input.
3) Virtual ground means it is not physically connected to ground but voltage at that point is 0V. In ideal Op-Amp parameters, the input Impedance is infinite. So, no current flows through Op-amp. As there is no current flowing through Op-amp, Current flowing through node will be 0A, therefore the voltage will be 0V.
4) Op amp needs low output impedances in order to drop its amplified voltage signals across the desired device effectively and not onto itself.
5) Summing amplifier is when we add input resistor which each equal in value to the original input resistor to the inverting amplifier that has a single input voltage applied to the inverting input terminal. This is because the input signals are effectively isolated from each other by the virtual earth node at the inverting input of the op-amp. A direct voltage addition can also be obtained when all the resistances are of equal value and feedback resistor is equal to input resistor. When the summing point is connected to the inverting input of the op-amp the circuit will produce the negative sum of any number of input voltages but when the summing point is connected to the non-inverting input of the op-amp, it will produce the positive sum of the input voltages.
6) The input voltage signal is applied directly to the non-inverting positive 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 negative input terminal via voltage divider network producing negative feedback. This closed-loop configuration produces a non-inverting amplifier circuit with very good stability, a very high input impedance, input resistance approaching infinity, as no current flows into the positive input terminal and a low output impedance. There is no current flows into the input terminal of the amplifier and V=V2. This was because the junction of the input and feedback signal ( V1 ) are at the same potential or we called as the the junction is a “virtual earth” summing point.
7) A voltage follower which is also called as a buffer 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. When a circuit has a very high input impedance, very little current is drawn from the circuit and the majority of voltage will fall across it. By having voltage follower, it can allow a designer to supply sufficient voltage to a load.

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

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Discussion Questions

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

Ideal op amps model 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 input voltage is the difference voltage between the two input terminals. The output voltage is measured with respect to the circuit ground node. The terminal characteristics of the ideal op amp satisfy four conditions which is:
-the current in each input lead is zero.
-The output voltage is independent of the output current.
-The voltage gain A is independent of frequency.
-The voltage gain A is very large, approaching infinity in the limit

Therefore, In a closed loop the output attempts to do whatever is necessary to make the voltage difference between the inputs zero and the inputs has no current

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

-Inverting amplifier is one in which the output is exactly 180 degree out of phase with respect to input for example  if you apply a positive voltage, output will be negative. Therefore, the output voltage changes in an opposite direction to the input voltage

3. What is the concept of virtual ground?

- the concept of  virtual ground is 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. The virtual ground concept aids circuit analysis in operational amplifier and other circuits and provides useful practical circuit effects that would be difficult to achieve in other ways.

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

-It  means that the output voltage is independent of output current. Real, physical op-amps only approximate this ideal and have very large input impedance and very low output impedance.

A high load impedance also means there won't be much current, which also means less power. The ideal op-amp has infinite input impedance and zero output impedance because it's easy to make the input impedance lower by putting a resistor in parallel or the source impedance higher by putting a resistor in series.

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

Characteristic: it is used to combine the voltages present on two or more inputs into a single output voltage.

Operation: it  is used as a virtual earth mixer as it is used to combine the voltages present on two or more inputs into a single output voltage. It finds many uses where several analogue signals need to be summed. One is as an audio mixer.

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

- Characteristic: Non Inverting amplifier is one in which the output is in phase with respect to input.

-Operation: for example,if you apply a positive voltage, output will be positive .  Output is an Non inverted(in terms of phase) amplified version of input.

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

In an inverting amplifier, the output voltage changes in an opposite direction to the input voltage. The output voltage changes in an opposite direction to the input voltage. resistor is   inserted between the non-inverting input and ground, this will reduce the input offset voltage due to different voltage drops due to bias current, and may reduce distortion in the op amps.

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Nik Dini Afique Irfan Bin Nik Zainudin-1818193

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Nik Dini Afique Irfan Bin Nik Zainudin-1818193

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1. Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages.
-The op-amp has one output terminal and two input terminals, called inverting input terminal and non-inverting input terminal. The op-amp also needs power supply for its operation and generally both positive and negative power supply are used simultaneously.
-Input resistance is infinity, open-loop differential mode voltage gain is infinity, open-loop common mode voltage gain is 0, gain bandwidth product is infinity, common mode rejection ratio is infinity, output resistance is 0. At close-loop operation, inverting input terminal is virtual ground.
- Since the input resistance is infinity, the input current is 0.
-Vo = Av ( V2 – V1), V1=V2 and make the open loop gain infinity.

2. Describe the operation and characteristics of the ideal inverting amplifier.
-Input signal is applied in the inverting input terminal and ground. The non-inverting terminal is connected to the ground. The feedback resistor is connected between the output and inverting input terminals. The inverting amplifier makes a 180 phase difference between input and output signals.
-The main benefit of this amplifier is that its gain does not depend on the active component parameter but depends on the passive component, so the gain of the amplifier is highly stable. According to Miller’s theorem, if the voltage gain of the amplifier is infinite, then this close-loop amplifier’s inverting input terminal acts as a virtual ground, that is the potential of this point is zero with respect to the ground, but physically it does not connect to the ground.
-Input resistance is infinity, input current = 0.

3. What is the concept of virtual ground?
-As the name indicates it is virtual, not real ground. It is considered as equivalent to ground. 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.

4. What is the significance of a zero output resistance?
-The output resistance 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 the maximum current to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load.

5. Describe the operation  and characteristics of the ideal summing amplifier
-The output of the amplifier is the function of the summation of the input voltages. To simplify the analysis, only three input signals are arbitrarily selected. The circuit analysis is done based on virtual ground and Kirchhoff current low.
-The close-loop amplifier inverting input terminal act as virtual ground.
-The input resistance is infinity, the input current is 0..

6. Describe the operation and characteristics of the ideal non inverting amplifier
-In this arrangement, input signal is applied in the non-inverting input terminal and ground. The inverting input is connected to the ground. The feedback resistor is connected between the output and inverting input terminals.
-In a non-inverting amplifier, the input and output signals are same phase. The main benefit is that its gain does not depend on the active component parameter but on the passive component, so the gain of the amplifier is highly stable. According to Miller’s theorem, if the voltage gain is infinite, then this close-loop amplifier inverting input terminal acts as virtual ground, that is the potential of this point is zero with respect to the ground, but physically it is not connected to the
ground.
-The analysis of the non-inverting amplifier is the same as for inverting amplifier
-We assume no current enter the input terminal since the input resistance is infinite.

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

Av = v0/vi = 1 + R2/R1

If R1 = infinity, whatever may the value of R1, (except R1 = infinity) close loop voltage gain of the amplifier is unity and positive; that is the output voltage follows the input voltage.

The advantage is that its input resistance is very large and output resistance is very small, so that it can be used as an impedance transformer or buffer circuit. The impedance transformer or buffer is used to avoid the loading effect on the circuit.

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Aliyatul Adleena Binti Abu Bashri (1815500)

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Aliyatul Adleena Binti Abu Bashri (1815500)

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1. The ideal Op-Amp model is the voltage gain is infinite, infinitely high input impedence, almost zero output impedence, the model mostly has two input terminal and one output terminal and lastly use dual power supplies which positive and negative terminal.

As for implications, the amplifier will draws no current and the voltage difference between inputs is zero.

2. Operation and characteristic of ideal inverting amplifier.

The input is connected directly to the inverting end of the Op-Amp causing the output voltage is 180 degree compared to input.

3.  Concept virtual ground

If one terminal is at the ground potential, the other terminal will appear to be at ground potential as well although they are not physically grounded

4. Significance of zero output resistance

The load will not cause the voltage to drop at the output and thus the load can get sufficient power to operate properly

5. Operation and characteristic of ideal summing amplifier

Summing amplifier is applying multiple inputs to either inverting or non-inverting terminal Op-Amp

6. Operation and characteristic of ideal non-inverting amplifier

The input voltage, Vi is connected directly to the non-inverting which is + terminal and thus creating the exact same signal as the input (signal not inverted)

Characteristic : high input impedence is required

7. Voltage follower

Input signal is applied directly to non-inverting input of amplifier. Then the output signal will not inverted and thus the output voltage is the same as input voltage, Vout = Vin.

Advantages

Impedence  matching or circuit isolation is more vital compared to amplifier because it maintains the signal voltage.

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MUHAMMAD ALIIF FARHAN BIN ABDUL MUIS (1810995)

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MUHAMMAD ALIIF FARHAN BIN ABDUL MUIS (1810995)

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1. The ideal op amp has these characteristics infinite voltage gain, infinite input impedance and zero output impedance. The implication is zero input current and zero input offset voltage.

2. The operation is the negative feedback that is the return of a portion of the output signal to be input signal. To make the negative feedback we have to inverting input of the op amp using an external feedback resistor.  The characteristics of the inverting amplifier is no current flow into input terminals and the differential input voltage is zero.

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 or the voltage at the particular node is zero.

4. The negative feedback lowers the effective output resistance  until it can be considered as zero. the significance is it can allow more current to go through it.

5.  The summing amplifier is used to add two signal voltages. The circuit of the summing amplifier is so simple to construct and it enables to add many signals together.

6. Non inverting amplifier will be  resulting the output voltage being equal to the input voltage, Vout = Vin.  The characteristics is 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 also called as a unity-gain amplifier, a buffer amplifier, and an isolation amplifier that is a op-amp circuit which has a voltage gain of 1. It means that the op amp does not provide any amplification to the signal/ the advantage is it have high input impedance and low input impedance.

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1810411

1) The characteristics of an ideal op- amp are.

-Open loop gain is the gain of the Op Amp without a positive or negative feedback. An ideal OP Amp should have an infinite open loop gain but typically it range between 20,000 and 2, 00000.

-Input impedence. It is the ratio of the input voltage to input current. It should be infinite without any leakage of current from the supply to the inputs. But there will be a few Pico ampere current leakages in most Op Amps.

-The ideal Op Amp should have zero output impedance without any internal resistance. So that it can supply full current to the load connected to the output.

-The ideal Op Amp should have an infinite frequency response so that it can amplify any frequency from DC signals to the highest AC frequencies. But most Op Amps have limited bandwidth.

-The output of the Op Amp should be zero when the voltage difference between the inputs is zero. But in most Op Amps, the output will not be zero when off but there will be a minute voltage from it.

2) Inverting amplifier.

Negative Feedback is the process of feeding back a fraction of the output signal back to the input, but to make the feedback negative, we must feed it back to the negative or inverting input terminal of the op-amp using an external Feedback Resisto. 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 now being called its Closed-loop Gain. 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. We must therefore separate the real input signal from the inverting input by using an Input Resistor.

3) Virtual ground.

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.

4) Zero output resistance.

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.

5) Summing Amplifier

Combine the voltages present on two or more inputs into a single output voltage. The operation is when more input resistors are added to the input terminal. The summing amplifier able to take almost unlimited number of inputs and none of one input should appear on another input.

6)  Non inverting amplifier

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 amplified version of input. The gain of the non-inverting amplifier circuit for the operational amplifier is easy to determine. 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

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.

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

The op-amp has one output terminal and two input terminals, called inverting input terminal and non-inverting input terminal. The op-amp also needs power supply for its operation and generally both positive and negative power supply are used simultaneously.

Input resistance is infinity, open-loop differential mode voltage gain is infinity, open-loop common mode voltage gain is 0, gain bandwidth product is infinity, common mode rejection ratio is infinity, output resistance is 0. At close-loop operation, inverting input terminal is virtual ground.

Since the input resistance is infinity, the input current is 0.

Vo = Av ( V2 – V1), V1=V2 and make the open loop gain infinity.

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

Input signal is applied in the inverting input terminal and ground. The non-inverting terminal is connected to the ground. The feedback resistor is connected between the output and inverting input terminals. The inverting amplifier makes a 180 phase difference between input and output signals.

The main benefit of this amplifier is that its gain does not depend on the active component parameter but depends on the passive component, so the gain of the amplifier is highly stable. According to Miller’s theorem, if the voltage gain of the amplifier is infinite, then this close-loop amplifier’s inverting input terminal acts as a virtual ground, that is the potential of this point is zero with respect to the ground, but physically it does not connect to the ground.

Input resistance is infinity, input current = 0.

3. What is the concept of virtual ground?

As the name indicates it is virtual, not real ground. It is considered as equivalent to ground. 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.

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

The output resistance 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 the maximum current to the load. This internal resistance is effectively in series with the load thereby reducing the output voltage available to the load.

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

The output of the amplifier is the function of the summation of the input voltages. To simplify the analysis, only three input signals are arbitrarily selected. The circuit analysis is done based on virtual ground and Kirchhoff current low.

The close-loop amplifier inverting input terminal act as virtual ground.

The input resistance is infinity, the input current is 0..

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

In this arrangement, input signal is applied in the non-inverting input terminal and ground. The inverting input is connected to the ground. The feedback resistor is connected between the output and inverting input terminals.

In a non-inverting amplifier, the input and output signals are same phase. The main benefit is that its gain does not depend on the active component parameter but on the passive component, so the gain of the amplifier is highly stable. According to Miller’s theorem, if the voltage gain is infinite, then this close-loop amplifier inverting input terminal acts as virtual ground, that is the potential of this point is zero with respect to the ground, but physically it is not connected to the ground.

The analysis of the non-inverting amplifier is the same as for inverting amplifier

We assume no current enter the input terminal since the input resistance is infinite.

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

Av = v0/vi = 1 + R2/R1

If R1 = infinity, whatever may the value of R1, (except R1 = infinity) close loop voltage gain of the amplifier is unity and positive; that is the output voltage follows the input voltage.

The advantage is that its input resistance is very large and output resistance is very small, so that it can be used as an impedance transformer or buffer circuit. The impedance transformer or buffer is used to avoid the loading effect on the circuit.

# data[].attributes.body
1. An ideal Op-Amp has infinite input impedance, zero output impedance and infinite open loop gain. The implication is the current into each input is zero and the input voltage is the difference between two input terminals.
2. the inverting amplifier receives feedback from the output of the amplifier.
3. The concept of virtual ground is that voltage at that node is almost equal to ground voltage(0V) and it is not physically connected to ground.
4. The significance of zero output resistance is it can provide more power in the signal.

5. The summing amplifier is used to combine the voltages present o two or more input into a single output voltage.
6. In non-inverting amplifier, the input voltage is applied directly to the non-inverting input terminal which means the output gain of the amplifier become +ve in value. The result of this is that the output signal is in phase with the input signal.
7.the voltage follower is known as a unity gain amplifier, a voltage buffer or an isolation amplifier. The output voltage is equal to input voltage. The advantage of using this circuit is Op-Amp can provide current and power gain.

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NURUL NAJIHAH BINTI BAKAR (1813424)

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

An ideal op amp is an op amp that has perfect conditions to allow it to function as an op amp with 100% efficiency. The ideal op-amp has infinite voltage gain,infinite bandwidth,infinite input impedance and zero output impedance.The implications of this ideal model in terms of input currents and voltages is the output attempts to do whatever is necessary to make the voltage difference between the inputs zero which applies only to closed-loop amplifier circuits, means that the feedback sent from the output to the input causes the two input voltages to become the same. Then, the input draws no current. This means that the input terminals look at the voltage placed across them but do not allow any current to flow into the op amp.

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

The ideal inverting amplifier is the output is inverted with respect to input. The voltage gain can be adjusted as greater than equal to or less than one. The input impedance is R1. The op-amp input resistance is large,so the current into the positive terminal and negative terminal op-amp inputs terminal will be small,essentially zero.

3. What is the concept of virtual ground?

The term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0 v). It is not physically connected to ground. A virtual ground is a node of a circuit that is maintained at a steady reference potential, without being connected directly to the reference potential. The virtual ground concept aids circuit analysis in operational amplifier and other circuits and provides useful practical circuit effects that would be difficult to achieve in other ways.

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

An ideal op amp will have zero output impedance. When an op amp produces its output signal, the op amp will  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.

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

The term summing amplifier is also named as adder, which is used to add two signal voltages. Summing amplifier is an amplifier that adds different inputs provided at inverting or non-inverting input terminals.It is highly used when we need to add different inputs. The output of the amplifier is the function of summation of the input voltages. The circuit analysis is done based on virtual ground and Kirchhoff current law (kcl).

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

The ideal non-inverting amplifier is no phase shift between input and output. The voltage gain is always greater than one. The input impedance is very large. The input resistance to the non-inverting amplifier is very high because the input current to the amplifier is also the input current to the op-amp which must be extremely small.

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

A voltage follower is also called a unity-gain amplifier, a buffer amplifier, and an isolation amplifier 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.The advantages are the input resistance  is very large and output resistance is very small, so it can be used as an impedance transformer or buffer circuit.The impedance transformer or buffer is used to avoid the loading effect on the circuit.

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1.  An ideal Op-Amp model has infinite input resistance and zero output resistance. As the result , there is no current flow in input terminal and zero input offset voltage.

2. In an ideal inverting amplifier, a portion of output signal will be returned to input signal. Its become out of phase with the input signal.

3. Virtual ground is a node or junction in which the voltage at that point is zero. No current flow through the Op-Amp.

4. The significance of a zero output resistance is that the output signal can be amplified multiple times than its input signal.

5. In an ideal non-inverting amplifier, a portion of the output signal will be returned to its input signal. All the signal are in phase. Next, input voltage signal is applied directly to non-inverting positive input terminal, output gain become "Positive" in value.

6. Ideal summing amplifier combines the voltages present on two or more inputs into a single output voltages.

7. Voltage follower also called as unity-gain amplifier which has voltage gain of 1. Does not provide any amplification to the signal. The advantages are its only draw a little current from power source and act as isolating buffer.

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1. Ideal op-amp model has infinite open loop voltage gain, infinite input impedance ,zero output impedance and infinite bandwidth. The input currents and voltages will be zero.

2. Inverting Amplifier is a normal OP-Amp in which the output is given as feedback to the inverted terminal of input by means of a feedback resistor. We apply a resistance between negative terminal of op amp and output terminal. this resistance is called negative feedback resistance that is represented by R with subscript f.

3. Virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground.

4. Low impedance in a voltage source is usually preferred because it helps to keep out the noise out of the circuit and maintain a stable output voltage.

5. 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 summing amplifier.

6. In this circuit the signal is applied to the non-inverting input of the op-amp. In this way the signal at the output is not inverted when compared to the input. However the feedback is taken from the output of the op-amp via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It has to be applied to the inverting input as it is negative feedback. It is the value of these two resistors that govern the gain of the operational amplifier circuit as they determine the level of 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. When a circuit has high input impedance , very little current is drawn from the circuit. If you are familiar with ohm’s law, you’ll know that I=V/R. Thus, greater the resistance, less current is drawn from the source. The power of the circuit is not affected when current is feeding a high impedance load.

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Nurul Nadirah Binti Jemidi 1815910
1. Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages.

Operational amplifier is an integrated circuit having well defined operating characteristics. It is a high gain linear amplifier circuit that is capable of amplifying the difference between two of its input signals and produce a single output signal. An operation amplifier is called a building block of analog circuit since any electronic circuit can be constructed by using op-amp. Op amp has one output terminal and two input terminals called inverting input terminal and non inverting input terminal.

For ideal characteristics of op-amp is
-the input resistance is infinity,
-open loop differential mode voltage gain is infinity,
-open loop common mode voltage gain is 0,
-gain bandwidth product is infinity,
-common mode rejection ratio is infinity,
-output resistance is 0
- at close loop operation, inverting input terminal is virtual ground.

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

Input signal is applied in the inverting input terminal and ground for this arrangement. The inverting amplifier makes a 180 degree phase difference between input and output signals. This amplifier has it gain that does not depend on the active component but but depends on the passive components so the gain is highly stable.

If the voltage gain of the amplifier is infinite, then this close loop amplifier’s inverting input terminal acts as a virtual ground (the potential of this point is zero with respect to the ground but not connect with ground physically.

3. What is the concept of virtual ground?
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.

4. What is the significance of a zero output resistance?
An ideal op-amp has zero output impedance. This means that the output voltage is independent of output current.
Real, physical op-amps only approximate this ideal and have very large input impedance and very low output impedance.
When the op-amp is part of a circuit like an amplifier, filter, etc., the input impedance of the circuit will, in general, be different from the input impedance of the op-amp proper.

5. Describe the operation  and characteristics of the ideal summing amplifier
The output of the amplifier is the function of summation of the input voltages. To simplify the circuit, only three input signals are arbitrarily selected. The circuit analysis is done baseed on virtual ground and KCL. Using KCL at the input node point i1+i2+i3+i(in)+i4=0. Since the input resistance of op-amp is infinity, so we can write i(in)=0.

6. Describe the operation and characteristics of the ideal non inverting amplifier
In this circuit the signal is applied to the non-inverting input of the op-amp. In this way the signal at the output is not inverted when compared to the input.
However the feedback is taken from the output of the op-amp via a resistor to the inverting input of the operational amplifier where another resistor is taken to ground. It has to be applied to the inverting input as it is negative feedback.
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. This means that Vin = Vout x R1 / (R1 + R2).

7. Describe the voltage follower. what are the advantages of using this circuit.
The voltage follower or buffer amplifier circuit, where the output is simply equal to the input. 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. It provides low output impedance to any circuit using the output of the follower, meaning that the output will not drop under load. The load is a 1k resistor in this case.the op-amp provides all the current needed to drive the load, without requiring any current from the input.

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Answers:

1. Ideal Op-Amp model has infinite input impedance and zero output impedance. The resistance at both input terminals is infinite therefore the current in each input lead is said to be zero. The output voltage is independent of the output current as the voltage gain is independent of the output current so it can be said that the output resistance is zero.

2. In an ideal inverting amplifier, the input signal is applied through resistor to the inverting Op-Amp input. The feedback resistor connects from the the output to the inverting input. The circuit 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.

3. The virtual ground means that the voltage at that particular node is almost equal to ground voltage which is 0V. However, it is not physically connected to ground.

4. 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. Therefore, Op-Amp needs low output impedance, so that it can drop its amplified voltage signals across the desired device effectively and not on itself.

5. An ideal 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. These amplifiers are used in an audio mixer to add different signals with equal gains. There are various resistors are used at the input of the summing amplifier to give a weighted sum. This can be used to change a binary number to a voltage in an AC (digital to analog converter). This amplifier is used to apply a DC offset voltage with an AC signal voltage.

6. Input voltage is applied to the non-inverting Op-Amp input. A voltage divider consisting of feedback resistors and another resistor connects from the output node to the inverting input. The circuit is called a non-inverting amplifier because its voltage gain is positive. This means that if the input voltage is increasing or going positive, the output voltage will also be increasing or going positive.

7. The voltage follower or unity-gain buffer is a unity-gain non-inverting amplifier. Compared to the non-inverting amplifier, the feedback resistor is replaced by a short circuit and resistor is omitted. The advantage of using this circuit is it is said to have 100% feedback as the output node is connected directly to the inverting input instead of through a voltage divider. Therefore, the circuit has unity voltage gain. The voltage follower is often used to isolate a low resistance load from a high output resistance source. Due to that, the voltage follower supplies the current to drive the load while drawing no current from the input circuit.

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MUHAMMAD ZULHAFIZ BIN ZULKIFLI [1812661]

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MUHAMMAD ZULHAFIZ BIN ZULKIFLI [1812661]

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1)  An ideal Operational Amplifier is a model consisting of 3 elements. It has a voltage-dependent voltage source with high gain, and modeled with 2 differential input terminals and a single output terminal. Some of its characteristics are infinite input impedance, zero output impedance, infinite voltage gain and infinite bandwidth.

Infinite input impedance makes the input current to be zero or cannot flow through each input. The differential input voltage is also zero.

2) An Inverting amplifier is an arrangement of op-amp when the input signal, is applied to the inverting (negative) terminal. It is called an inverting amplifier because its voltage gain is negative. For example, if the input voltage is low, the output voltage produced will be high, and vice versa. The op-amp is connected to feedback to produce a closed loop operation. The voltage of both input terminal is the same and since the input impedance is infinity, no current flow into the both input terminals and instead it will flow through the resistor. So, both input voltage is zero.

Some of its characteristics are infinite input impedance, zero output impedance, and infinite open loop gain.

3) Virtual ground is a term to say that the voltage at that particular node is almost equal to ground voltage which is 0 V while it is not physically connected to ground. Because of the zero voltage, it is called “virtual” ground as if it is connected to the ground. This concept is very useful in analysis of op-amp circuits and it will simplify a lot of calculation.

4) The output resistance is the measure of the opposition to current flow. An ideal voltage source 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, causing the output voltage to rise. The low resistance also helps in reducing the noise and interference.

5)  Summing amplifier a type of inverting amplifier configuration. It enable us to sum up several signals together. In an 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 a summing amplifier, the value of output voltage is the total of the input voltages that is parallel to one another.

6) A Non-inverting amplifier is an arrangement of op-amp when the input signalis applied to the non-inverting terminal. The voltage gain of non-inverting amplifier is at positive input terminal. The input voltage signal is applied directly to the positive input terminal, which means that the output gain of the amplifier will become positive in value. The voltage gain is always greater than one. The result of output signal is in-phase with the input signal.  A non-inverting amplifier amplifies an input signal without inverting the signal. Meaning that, if the input signal is positive, the output signal is positive, and vice versa.  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.

7)  A voltage follower is an op-amp arrangement that is known as unity-gain amplifier or buffer amplifier 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. 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.

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Siti Nur Farzana Binti Mohd Nasir   1818400

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Siti Nur Farzana Binti Mohd Nasir   1818400

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1. The ideal Op-Amp model has one output terminal and two inputs terminals which are inverting input terminal and non-inverting input terminal. Ideal op amps will have an infinite open loop gain,infinite input resistance, zero output resistance and at close loop operation,inverting input terminal is virtual ground. This ideal model will cause no current flows into either input terminal and that the differential input offset voltage is zero.

2.    The ideal inverting amplifier with the input signal is applied in the inverting input terminal and ground while the non inverting input connected to the ground. Two resistors are connected in the circuit in such that a resistor feeds the input signal while another resistor between the output and Inverting input terminals. Here when the input signal is positive the output will be negative and vice versa. The voltage change at the output relative to the input depends on the ratio of the resistors.Therefore the voltage gain is R2/R1.

3.    Virtual ground is a concept that is very useful in analysis of Op-Amp circuits and it will make  the calculations very simple. The voltage at that particular node is almost equal to ground voltage which is 0V.

4.    The significance of a zero output resistance is to make 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 resistance present in a circuit. In order for the voltage to drop across the output load, that load must be of greater resistance than the output of the op-amp.

5.    The ideal summing amplifier enable to add many signals together. These input signals are given to the inverting terminal of the operational amplifier using input resistors. Non-inverting terminal of the operational amplifier is given to the ground terminal using a resistor.A feedback resistor is placed between input inverting and output terminals. The resulting output will be the sum of all the input voltages applied but inverted. So, the formula to find the output voltage is VOUT = – (Rf/RIN) VIN

6.    The ideal non inverting amplifier has the non inverting input receives the signal while the Inverting input is connected with ground.The feedback resistor connected between output and inverting input terminals. When the input signal moves either positive or negative, the output will be in same phase.The voltage gain in this case will be always higher than 1 so (1+R2/R1).

7.    Voltage follower is a Op-Amp 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. The advantage of voltage follower is that its input resistance is very large and output resistance is very small,so it can be used as buffer circuit. The buffer is used to avoid the loading effect on the circuit.

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Muhammad Faizuddin bin Ahmad Farid 1813561

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Muhammad Faizuddin bin Ahmad Farid 1813561

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1. An ideal op amp has infinite voltage gain at all frequencies and infinite input impedance. Thus, implicating in zero input current and zero input offset voltage.

2. In ideal inverting amplifier, the voltage at the inverting terminal is equal to non-inverting terminal. The non-inverting input of the op amp is connected to ground so that the inverting input must be virtually at earth potential.

3. Virtual ground means that the voltage at the particular node is almost equal to the ground voltage (0v). It is not physically connected to the ground.

4. The significance of a zero output resistance is the op amp can supply more current without tge voltage changing much.

5. Ideal summing amplifier is another type of op amp circuit configuration that is used to combine the voltages present on two or more inputs into a single output voltage. The operation is when more input resistors are added to the input terminal, each equal in value to the original input resistor. Ideal summing amplifier should be able to take almost unlimited number of inputs and none of one input should appear at another input.

6. Ideal non-inverting amplifier is one in which output is in phase with respect to the input. The operation is by applying a small part of the output voltage back to the inverting input terminal via voltage divider network. This closed loop configuration produces a non-inverting amplifier with very good stability, high input impedence (approaching infinity) and no cirrebt flows into the positive input terminal.

7. Voltage follower is a special type of non-inverting amplifier circuit produced when a circuit have a fixed gain of 1 as all the output voltage would be present on the inverting input terminal. The advantages of voltage follower is that it can be used when impedance matching or circuit isolation is more than amplification as it mantains the signal voltage.

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Nur Izzah Nazurah binti Kusuadi   1816500

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Nur Izzah Nazurah binti Kusuadi   1816500

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Answers :

1. An ideal op-amp has these characteristics; 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. The implications of this ideal op-amp in terms of input current and voltage is when the input resistance is infinite, the input current flow into either input terminals will be zero and the differential input offset voltage is zero.

2. In an inverting amplifier circuit, the op-amp inverting input receives feedback from the output of the amplifier. Assuming the op-amp is ideal and applying the concept of virtual short at the input terminals of op-amp, the voltage at the inverting terminal is equal to non-inverting terminal. The non-inverting input of the op-amp is connected to ground. As the gain of the op-amp itself is very high and the output from the amplifier is only a few volts, this shows that the difference between the two input terminals is exceedingly small and can be ignored. As the non-inverting input of the operational amplifier is held at ground potential this means that the inverting input must be virtually at earth potential.

3. The concept of virtual ground is the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground.

4. Op-amp needs zero output resistance so that it can drop its amplified voltage signals across the desired device effectively.

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.

6. The op-amp non-inverting amplifier circuit provides a high input impedance along with all the advantages gained from using an operational amplifier. 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 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. A voltage follower acts as a buffer, providing no amplification or attenuation to the signal. Voltage follower gives an efficient isolation of output from the input signal.

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1. The ideal Op-Amp model which the things have infinite input impedance and zero output impedance and most of op amps use dual power supplies. The implication of the ideal op amps model is zero input current and zero input offset voltage.

2. The operation of the ideal inverting amplifier, the input signal was opposite with the output signal as it was inverted. Some of the output signal was returned to the input. The returned signal was same as the output signal, but out of phase, which called as 'Negative Feedback'.

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

4.  The significance of a zero output resistance was it can supply a lot of current from them and carry large loads.

5. The ideal summing amplifier had many number of input signal which can be summed using an op-amp. The sum of the input signal is amplified to create the output signal. The summing point is connected to the inverting input of the op-amp. The circuit will produce the negative sum of any number of input voltages.

6. In the non-inverting amplifier, the input signal and the output signal will be the same phase since it was non-inverting. Some of the signal returned to the inverting input also in the same phase. This idea of negative feedback is that the feedback opposes the original input signal.

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

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1. the ideal op-amp model
-  Infinite input impedance so that the a little current is required to make voltage.
-  Infinite open loop gain so that  voltage differential on the two input terminals will result in an infinite voltage on the output.

2. The operational amplifier is connected with feedback to produce a closed loop operation. Remember about inverting amplifiers, no current flows into the input terminal and that V1 always equals V2.  One of the main features of the inverting amplifier circuit is the overall gain that it produces. The voltage gain, Av, is actually the output voltage (Vout) divided by the input voltage (Vin), it is the number of times the output voltage is larger than the input voltage.

3.  Virtual ground for some purposes we can consider it as equivalent to ground. In op-amps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0 V).

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.

5.  The term summing amplifier is also named as adder, which is used to add two signal voltages. The circuit of the voltage adder is so simple to construct and it enables to add many signals together.  The Summing Amplifier is a very flexible circuit, enabling us to effectively  “Sum” 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.

6.  The op amp non-inverting amplifier circuit provides a high input impedance along with all the advantages gained from using an operational amplifier. The gain of the non-inverting 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. A voltage follower is also known as a unity gain amplifier, a voltage buffer, or an isolation amplifier. In a voltage follower circuit, the output voltage is equal to the input voltage; thus, it has a gain of one (unity) and does not amplify the incoming signal.  The voltage follower allows us to move from one circuit to another and maintain the voltage level. It preserves the voltage source signal. This is why it’s also called a buffer or isolation amplifier.

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1.   The input impedence considered near to infinity and the output impedence is near to zero. The implications of this ideal model is zero input current and zero input offset voltage

2. The input signal will be opposite on that output signal. he signal comes in and a portion of it is returned to the input. The coming in and returning signal is all same except that it is out of phase. It tend to weaken the final output. The returned signal was same as output signal but out of phase (negative feedback)

3. Node of circuit that is maintained at steady reference potential also known as potential at ground terminal. However, unlike the actual ground terminal, the current may be restricted.

4.  Can delivered a lot of current and carrying large load passing it

5. Summing amplifier is a type of op amp circuit which can be use to add signal. . The sum of the input signal is amplified by a certain factor and made available at the output .Any number of input signal can be summed using an op-amp. The operation of summing amplifier is connected to the inverting input of the op-amp the circuit will produce the negative sum of any number of input voltages.When the summing point is connected to the non-inverting input of the op-amp, it will produce the positive sum of the input voltages.

6.   Input signal is sent and since the output will be the same phase as the input.The signal is fed back to the inverting input and  same phase. This idea of negative feedback is that the feedback opposes the original input signal.

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

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1. An ideal op-amp is usually considered to have infinite one-loop gain G = v(out)/v(in), infinite input impedance R(in), infinite output voltage range and zero output impedance R(out). The implications are that the input current will be zero.
2. The output is fed back to the input of the op-amp through an external resistor, called feedback resistor R(f). Feedback connection provides an accurate control of the gain of the op-amp, depending on the application. An inverting amplifier inverts the input signal while amplifying it. A positive going signal at the input of an inverting amplifier results in a negative going signal at the output and vice versa.
3. A virtual ground is a node that is sustained at a steady reference potential that is considered to be the surface of the earth, but in this case it is not connected directly to the reference potential because the potential at the node is similar to that of the actual reference potential which is 0V.
4. Op-amps are voltage gain devices, using the concept of voltage divider, they amplify a voltage fed into the op-amp and give out the same signal as output with a much larger gain. In order for an op-amp to receive the voltage signal as its input, the voltage signal must be dropped across the op-amp.
5. A summing amplifier is a handy circuit that enables us to add several signals together. A summing amplifier keeps the potential of the negative terminal very close to the positive terminal. The output the becomes V=R(connected between the negative terminal of op-amp and its output terminal) x I(total currents from all inputs).
6. The non-inverting amplifier provides a high input impedance along with all the advantages gained from using an op-amp. The signal is applied to the non-inverting input of the op-amp. In this way the signal at the output is not inverted compared to the output. The feedback is taken from the output of the op-amp via a resistor the inverting input of the op-amp where another resistor is taken to the ground. This is a negative feedback.
7. A voltage follower is an op-amp that has a voltage gain of 1. This means that there is no amplification to the signal. The output voltage follows directly the input voltage. A voltage follower acts as a buffer, providing no amplification nor attenuation to the signal. The advantage of this circuit draws very little current. Thus, the power of the circuit is not affected when current is feeding a high impedance load. Another advantage is its importance in voltage divider circuits. According to Ohm's Law, V=IR. In a circuit, voltage divides up according to the resistance or impedance of components. Because of op-amp's very high input impedance, the majority of voltage will fall across it. This allows a circuit designer to supply sufficient voltage to a load.

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Op Amp Characteristics - Negative feedback

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Op Amp Characteristics - Negative feedback

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Continuing in 11.1 and the subject is "Negative Feedback is Required"-it often is required for op amps.

Negative feedback is the return of a portion of the output signal to the input signal (out-of-phase).

When an op amp has feedback, its operation is closed loop; with no feedback, it is open loop.

Couple of concepts here to consider: Here we have two op amps that are configured to use negative feedback. One is using the inverting input and the other is using the non-inverting input. It's needful to look at the differences in the configuration.

Let's just look at, for example, here we have an input signal. The signal comes in like so. Notice it's inverting, so that signal will be just the opposite of that on the output. Notice the signal comes in and a portion of it is returned to the input. Here we have this signal coming in and the returning signal is the same signal except that it is out-of-phase. This will tend to attenuate the final output.

We mentioned something about closed loop and open loop and often you'll see a term called "AOL," not for America Online, that is for gain open loop. Gain open loop is kind of like beta was in transistor. The open loop gain, for example, for a 741 can be anywhere from 20,000 to 100,000. We call this gain ACL.

This is for gain closed loop, and that's what we're looking at when we incorporate negative feedback, is gain in a closed-loop configuration. If this resistance wasn't here, you'd feed the input and it'd come out here and there's no loop at all, it's just open loop. When we close this loop, like this, that's why we're calling it gain closed loop. When we do this, we can get a very predictable gain.

The diagrams here, let's see, we're using inverting and non-inverting ... Okay, we looked at the inverting, let's look at the non-inverting. 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.

There's something that we haven't mentioned. There is a concept, sometimes it's referred to as a virtual ground, sometimes 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.

Output Resistance

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.

With the 741, just as an example, it has 25 ohms of resistance with gain open loop and nearly zero with negative feedback. In fact, if we went in and did the formalized calculations for that, we would find that with negative feedback the resistance is usually less than 1 ohm, so for practical purposes, we consider it to be zero.

Output Voltage Swing

The output of an op amp can normally have output voltage swings that are within 2-3 V of the supply voltage.

If the output tries to exceed these limits, it will be distorted. It will result in clipping; we will have saturation in one of the output transistors. Where clipping occurs, it is commonly referred to as the "rails" and we'll get to that in a couple of minutes.

Here we have some examples and here we have an amplifier with, in each case here, the gain is 1,000,000, the supply voltages are +15 and -15. The only thing that is changing is the input and the output. In this case, here we have 1 microvolt of input and so we come in with 1 microvolt, we amplify it 1,000,000 times and so it has 1 volt of output. The input and the output have the same shape except that it's been significant amplified.

Then in the next circuit here, everything's the same except now we're putting in 10 microvolts, so now we're getting 10 volts out.

Next screen, we feed in 15 microvolts and now the op amp is unable to provide that much amplification. We're sending it a signal but the supply voltage are going to limit our output. Notice that we're not getting all the way to 15, in this case we're getting to 12 and this value will actually vary depending upon the size of the load resistance [inaudible 0:08:52]. If you have a very large load resistance, you might get a little more than that. If you have a very small load resistance, you actually might get a little less than this.

In this case, here we have 20 microvolts and, again, now we're having severe attenuation and the output signals going to look kind of like this. It's almost beginning to look like a square wave, no, not quite, but it's getting there.

These signals where it gets clipped off, this would be referred to as the rails of the op amp outputs because it's the limitation where it can't go any further.

Open Versus Closed-loop Gain

We've alluded to this already. An ideal op amp has infinite voltage gain at all frequencies. This isn't going to be true, but we'll just say that's the ideal.

Practical op amps have open-loop gains ranging from 100,000 to over 1,000,000-and notice this-at low frequencies. We will look at a graph in a later presentation.

The internal voltage gain of an op amp decreases at higher frequencies. When we look at this graph we will see the decrease in voltage gain as frequency increases.

We've looked briefly at open- versus closed-loop gain, we looked at output voltage swings, output resistance, and we talked about the concept of negative feedback, which is usually used in operational amplifiers.

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Op Amps Characteristics (Part 3) - Negative Feedback

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Continuing in 11.1 and the subject is "Negative Feedback is Required"-it often is required for op amps. Negative feedback is the return of a portion of the output signal to the input signal (out-of-phase). When an op amp has feedback, its operation is closed loop; with no feedback, it is open loop.

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We're in Chapter 11 and we'll be looking at the subjection of operational amplifiers and circuits and they're commonly referred to as "op amps" for short.

We'll be looking at this particular section, 11.1, in three different sections and so we're starting out with A.

Introduction

An operational amplifier (op amp) refers to an integrated circuit having well-defined operating characteristics. We will be looking at those operating characteristics.

A single IC may contain a single op amp, or multiple op amps may be contained on a single IC. So you may see an IC that is just one op amp or you may see an IC that actually has multiple op amps on the same piece of silicon.

Op amps are widely used in computer circuits and industrial computer applications.

Op Amp Characteristics

Op amps in electronic circuits may be assumed to be ideal for design and troubleshooting purposes. This term that we're using here, "ideal," we'll be looking at that more throughout this section.

This addresses things like infinite input impedance and zero output impedance. As we go along in this chapter, we'll find that for purposes of design and troubleshooting, the input impedance can be considered to be infinite. It isn't infinite, but it is so large that for practical purposes, we consider it to be infinite. Also, the output impedance, though it is not technically zero, it is close to zero that for design and troubleshooting purposes we can consider it zero. There will be other properties of an op amp that we will view as ideal as well.

The symbol for an op amp includes two input terminals, an output terminal, two power supply connections, and one or more compensation terminal. We'll be looking at those terminals in a few minutes.

The op amp is essentially a differential amplifier with a single-ended output. This is what your text says and most of them are this way. Remember when we talked about a differential amplifier, that it has two inputs and on the differential amplifier portion it can have two outputs-one was inverted and one was non-inverted. Most operational amplifiers will only use the non-inverted output. However, there are some op amps out there that will actually use both. So it is not an in concrete thing that they only have single-ended outputs, it's just that most are that way.

Most op amps use dual power supplies. When we say dual, we mean that there's a positive and a negative supply associated with them.

Some op amps have more than one compensation pin. These pins are used to fine-tune the behavior of the op amp.

With 0 V on the input pins, some output voltage may result. This is called the offset voltage and could be either positive or it could be negative.

In some designs, the compensation pins are used to null out this offset voltage. You need that to recall that ... Actually, you don't need to recall, but with op amps, the gain is typically 100,000 and so the tiniest voltage on the inputs can cause a rather large output and so that's why sometimes they have these compensation pins to adjust for that output voltage that results.

Schematic Representation

The 741 is a very common op amp and this is the multi-sym representation of the 741. We'll notice the inputs. There are inputs two and three. This would be the inverting input. This is the noninverting input, shown by the minus and the plus. Pin four is one of the power supply connections, it is for the negative power supply, and seven is for the positive power supply. Pins one and five are used for offset if they are deemed necessary to be used. They are not commonly used, to be honest with you. Pin six is the output.

Down here, we just have the basic symbols showing inputs and outputs and in many circuits, all you'll see is this, they don't give you all of the detail.

This is the schematic representation of the same thing from the previous page that we looked at regarding the symbol and the abbreviated symbol.

This is our introduction to op amps. We looked at schematic representation, we looked briefly at offset voltage, and we looked at some of the characteristics of an op amp.

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We're in Chapter 11 and we'll be looking at the subjection of operational amplifiers and circuits and they're commonly referred to as "op amps" for short. We'll be looking at this particular section, 11.1, in three different sections and so we're starting out with A.

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We're continuing in 10.1 and we're looking at amplifier basics. Characteristics of amplifiers are common across devices including integrated circuits. Gain is a term to indicate the increase in signal given by an amplifier. Gain is expressed as gain = output/input and is commonly represented as A. Amplifiers may be designated to amplify current, voltage or power.

dB Gain

Gain or loss can also be expressed as decibels as in dB. Decibels are based upon logarithms and provide a convenient way to express very large ratios. Conversion formulas for voltage, current, and power are...

Here we have the conversion to decibels for voltage, current, and power. Now, you'll notice here. For voltage, we're going to take 20log of the output over the input. Let's just do some examples here. Let's pretend that our output voltage--and we'll just use very round numbers for ease. The output voltage is 100. The input voltage is 1. If we were evaluating gain, we would say the amplification was the input or the input is 100 times larger than the input.

Now, to look at the gain in decibels, we will need to bring out our calculator. We're going to say 100 and then we'll take the log of 100 which is 2, and then we need to multiply it by 20 so times 20 equals, and the value is 40. We could say that we have and what we commonly do say is that we see 40 decibels of gain in this amplifier, and this would be voltage gain, 40 dB of voltage.

Now, keep in mind that when we use the term decibel, this is a unitless value. By that, I mean this simply represents the relationship between input and put since we have 1 volt of input, 100 volts of output. We're taking 20 times the log of 100. Let's look at current and we'll amplify this side.

Let's say we had the same amplifier and this wouldn't necessarily be always the case, but let's just pretend that in the same amp, we also had a current gain. This time, the current gain would be 100 milliamps and then we had 1 milliamp of current. Like I said, this would not necessarily be the case, but just for ease of numbers again, we'll do the same thing.

Now, we could say the current gain is 100. To simply say, 100 times the input. Now, if we were taking the log of that, we took 20log times--again, it would be just 100. We get the same thing. Again, we would say we get 40 dB. Now, the fact is that, again, this is a much smaller unit. This is in milliamps, but the ration remains the same so the output is the same. Again, we're looking at--the decibels is unitless. It simply represents the relationship between input and output. When we're looking at voltage in current, the relationship is going to be 20 times the log of that value.

Now, when we look at power gain, we're going to find that power gain is not 20log. It's going to be 10 times the log. Now, recall that when we calculate power, it is the function of voltage and current. Now, amplifiers are usually optimized for either voltage current or power, but when it comes down to the final analysis and you have to calculate what is the power, you simply look at what is the voltage and what is the current in the circuit and you multiply them out. What we could do, if we pretend that this was the same amplifier, we could pretend that this is the same--we want to evaluate the power for this amp. When we say, well, we had 100 volts of input, we had 100 milliamps, so that would represent 100 times. The 100 milliamps would represent the total power. The 100 times the 100 is 10,000 to keep our units right. I remember this is watts. Since this is milliamps times 100, then this would be milliwatts.

Our input, we would have 1-volt times 1--again, this is in milliamps so this would be 1 milliwatts. Now, we're looking at 10,000 milliwatts of power. Now, there's quite a difference between 100 over 1 and 10,000, but we're looking at the same amps. Let's again look at our calculator and calculate what is the power out here. We start out with 10,000 and we take the log of that. Now, remember this time it's times 10 so times 10, and notice that we still get 40. Interestingly enough, remember this is actually what we would expect since this is the same amplifier, and this brings into play why we take 10 times the log by 20 with voltage and current.

Okay, let's take a little closer look. With our voltage gain, we had 100/1. Remember that when we do decibels, we're looking at the log. Remember, when we do logs, we're thinking about the log represents the exponent. When we take the log of 100, we're looking at what exponent we would raise 10 to get this value. In this case, the log would be 2 and so the log of 100 is 2. Remember the 10 times 10. That's where we get that value.

Since we're doing the decibels, remember to calculate the decibels, we would take 20 times that exponent and times 20, and that's where we got the value of 40 dB. With power, it was much the same. The value was 10,000/1. Again, the log represents the exponent if we had 10 and we wanted to find out what is the exponent that we would raise 10 to get 10,000. Well, that value would be 4. If we just took the log of 10,000, we would get 4, but to convert it to decibels, we would take that times 10. Hence, we get our value which we previously calculated which was 40 dB.

Okay, this addresses the first item that we are looking at in this section which has to do with amplifier basics. We're looking at the term of gain so we looked at the value A which represents the value of amplification. Then we looked at converting that gain into decibels which are generally used to represent very large values.

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We're continuing in 10.1 and we're looking at amplifier basics. Characteristics of amplifiers are common across devices including integrated circuits. Gain is a term to indicate the increase in signal given by an amplifier. Gain is expressed as gain = output/input and is commonly represented as A.

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1. Describe the ideal Op-Amp model and describe the implications of this ideal model in terms of input currents and voltages.
2. Describe the operation and characteristics of the ideal inverting amplifier.
3. What is the concept of virtual ground?
4. What is the significance of a zero output resistance?
5. Describe the operation  and characteristics of the ideal summing amplifier
6. Describe the operation and characteristics of the ideal non inverting amplifier
7. Describe the voltage follower. what are the advantages of using this circuit.