Question

A 4-bit MOD-6 ripple counter uses J-K flip-flop. If propagation delay of each flip-flop is 20nsec, then the maximum clock frequency used is______$MHz.$

• A. 12.5

Answer 1

The correct option is A 12.5
A 4-bit ripple counter uses 4 flip-flops and total delay,
$T_d=n{t}_{pdf}=4\times 20\times {10}^{-9}{T}_d=80\times {10}^{-9}sec$
Maximum clock frequency that can be used is
$f=\frac{1}{T_d}=\frac{1}{80\times 10}=12.5MHz$