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The two types of counters that are frequently employed in digital circuits are synchronous and asynchronous counters. The differences between synchronous and asynchronous counters are carefully written on this page, along with their properties, applications, and functioning.
What is a Counter?
A sequential logic circuit using flip-flops as its core component is referred to as a counter. The clock pulse is applied to a cascade combination of several flip-flops. In digital circuits, counters are often employed to count, and the total number of counts corresponds to the number of clock pulses received.
What is Synchronous Counter
The parallel Counter sometimes referred to as a synchronous counter, is one in which all of the flip-flops that make up the Counter are concurrently timed by the same clock input. In essence, each flip flop in the cascade connection of the synchronous Counter is independently linked to an external clock. This makes it easier to clock all the flip-flops that make up the Counter simultaneously using the same clock input. This indicates that each flip flop’s output changes with the clock input.
Because of this, each flip flop’s state changes concurrently due to the same clock signal. As a result, this Counter has no ripple effects and no propagation delays.
What is Asynchronous Counter
Since the flip-flops that make up the counter are connected in serial here, and the input clock pulse is given to the first flip-flop in the connection, this type of Counter is also known as a serial counter. Here, the clock input oscillates as the output of the initial flip-flop caused by the clock signal is passed on to the subsequent flip-flop in the forward direction.
The current output also serves as the clock input for the following output in the same manner. As a result, the time signal in the asynchronous Counter delays somewhat after travelling through each flip-flop. As a result, there is a propagation delay.
Differences between Synchronous and Asynchronous Counter
Depending on the applied clock pulse, there are two types of counters. Asynchronous Counter and synchronized Counter are these counters.
Various flip flips in an asynchronous counter, sometimes called a ripple counter, are triggered by different clocks rather than simultaneously. Asynchronous counters operate more slowly than synchronous counters because the same clock simultaneously activates all flip-flops in a synchronous counter.
Let’s see how these two counts vary from one another:
Synchronous vs Asynchronous
| Synchronous | Asynchronous |
| All flip flips in a synchronous counter are triggered simultaneously by the same clock. | Various flip-flops are activated with different clocks rather than simultaneously in an asynchronous counter. |
| Asynchronous counters operate more slowly than synchronized counters. | The asynchronous Counter operates more slowly than the synchronous Counter. |
| There are no decoding issues using Synchronous Counter. | The asynchronous Counter produces decoding errors. |
| Parallel Counter is another name for Synchronous counter. | Serial Counter is another name for asynchronous counter. |
| Due to the growing number of states, creating and implementing synchronized counters is difficult | Designing and implementing an asynchronous counter is relatively simple. |
| Any desired count order can be used with a synchronized counter. | The asynchronous Counter will use only a fixed count sequence (UP/DOWN). |
| Examples of synchronized counters are Johnson and Ring counters. | Ripple UP counter and Ripple DOWN counter are two instances of asynchronous counters. |
| There is less propagation latency with synchronous counters. | In an asynchronous counter, the propagation latency is significant. |
| Also known as Comparative Counter | also known as Numerology Counter |
| The same clock signal is used to simultaneously activate each flip-flop. | A separate clock signal is used to activate each flip-flop at a different moment |
| Decoding mistakes not created | Decoding mistakes Produced |
| Fast operating velocity | reasonably slow operating velocity |
| Complex Design | Simple Design |
| signal propagation delay Quite Low | signal propagation delay reasonably high |
| Counting order Not Fixed | Counting order Fixed |
| Flip-flops all undergo synchronous state transitions. | With a change in clock input, none of the flip-flops’ states change simultaneously. |
| The longest settling time possible among all the flip-flops in the setup. | the sum of the settling times for every single flip-flop. |
| not Exists Direct flip-flop connectivity | Direct flip-flop connectivity Exist |
| Multiplexing circuits, alarm clocks, and other moving machine control devices | in frequency dividers, ring, and Johnson counters, etc. |
