Question

A 4 bit ripple counter and a 4 bit synchronous counter are made using flip flops having a propagation delay of 10 ns each. If the worst case delay in the ripple counter and the synchronous counter be R and S respectively. then

• A. R = 30 ns, S = 10 ns
• B. R = 10 ns, S = 30 ns
• C. R = 40 ns, S = 10 ns
• D. R = 10 ns, S = 40 ns

Answer 1

The correct option is C R = 40 ns, S = 10 ns

Prop. delay of 4 bit ripple counter
R = 4 $\times$ $t_{pd}$ = 40 ns
In synchronous counter all flip-flops are given clock simultaneously so, S = 10 ns.