There are two main types of counters: Asynchronous and Synchronous counters.

This type of counters have JK Flop-Flops arranged in a way that the output of one flip-flip feeds the clock of the following flip-flop [1] as shown in the figure below:

The asynchronous counter (also called the ripple counter) is relatively slow due to the fact that each flip-flop’s clock is dependent on the output of the previous flip-flop and because they have a non-zero propagation delay. The synchronous counter eliminates this issue as we will see in the next section [1].

Counter is an electronic circuit used to count the number of times an event occurs. In digital electronics counters are constructed using series of flip-flops. Although any flip-flop can be suitably connected to form a counter, most widely used are D and JK flip-flops

Counter is a sequential circuit. A digital circuit which is used for a counting pulses is known counter. Counter is the widest application of flip-flops. It is a group of flip-flops with a clock signal applied. Counters are of two types.

A binary mod 4 counter has 4 count states, from 000 to 011. So the mod 4 counter counts from 0 to 4. This means, in general a mod N counter can contain n number of flip flops, where 2n = N.

There are two types of counters available for digital circuits, they are

Counters can be categorized into different types according to the way they are clocked. They are