# Synchronous Series Carry Counter

Synchronous Series Carry Counter is such a synchronous counter where inputs of flip-flops are connected in such a manner that only those flip-flops that are toggle on a given clock will have input value as the logic 1. The advantage of this counter is that it reduces the decoding error.

**Block Diagram of Synchronous Series Carry Counter:**

Here is the block diagram of a 4-bit (MOD-16) series carry counter.

In the above counter:

- A toggles for every CLK pulse is applied.
- B toggles when A = 1 and CLK pulse is applied.
- C toggles when B = 1 and A = 1 and CLK pulse is applied.
- D toggles when C = B = A = 1 and CLK pulse is applied.

**Truth Table for Series Carry Counter:**

**Note:**

In order to get the synchronous down counter, complemented output (A’, B’ etc.) of each stage is connected to the input of the next stage.

**Total Time Delay :**

The total delay for synchronous series carry counter is:

T >= t(pd) + (n-2) x t(pd of AND gate)

As the number of bit increases, the propagation delay of flip-flops and the propagation delay of AND gate also increases, this will increase the total delay of the circuit.

**Advantage of Series Carry Counter:**

Most important advantage of the series carry counter is that it reduces the decoding error.