The synchronous counter also referred to as a parallel counter is the one in which each establishing flip flops are clocked with the similar clock input at the same time. In the synchronous counter, all the flip-flops in the cascade network are independently linked to an external clock.
This supports the clocking of all the flip-flops constituting the counter simultaneously instant with a similar clock input. This represents the output of each flip-flop change in synchronization with the clock input. In the synchronous counter, the similar clock pulse is moved to the clock input of all the flip-flops. The clock signals make by all the flip-flops are equal to each other.
The asynchronous counter is also called the ripple counter. Asynchronous Counters use flip-flops that are successively linked so that the input clock pulse arrives to ripple through the counter. In an Asynchronous counter, in which the clock pulse ripples over the circuit. The n-MOD ripple counter forms by merging n number of flip-flops. The n-MOD ripple counter can count 2n states, and therefore the counter resets to its original value.
In the Asynchronous counter, the demonstrate counter's output moved to the input of the next counter. Therefore, the counters are linked like a chain. The disadvantage of this system is that it generates the counting delay, and the propagation delay also appears during the counting stage.
Let us see the comparison between Synchronous Counter and Asynchronous Counter
|Synchronous Counter||Asynchronous Counter|
|The simultaneous clock pulse is given to
all the flip-flops.||The clock pulse is given to the first flip-flop and the output of the first flip-flop acts as a clock to the next and so on.|
|It is quick to compare to asynchronous counters.||It is slow as compare to synchronous counters because the 2nd flip-flop has to wait just before the 1st flip-flop provides the output.|
|An additional combinational circuit is
required for its design. This circuit
becomes complicated.||A circuit is clean as compared to synchronous counters.|
|The number of operations can be much greater than the asynchronous counters.||The number of operations is secondary to the synchronous counters.|
|In the synchronous counter, the count sequence is not permanent as it is created to work in an accurate series of states.||The count sequence of the asynchronous counter is permanent i.e., UP and DOWN.|
|In synchronous counters, each flip-flop is independently clocked therefore direct interconnection between them does not occur.||In the asynchronous counter, the output of the preceding acts as the clock input for the next therefore direct interconnection between the flip-flops occurs.|