Question

A 8-bit modulo 250 ripple counter uses JK flip-flops. If the propagation delay of each flip flop is 500 ns, the maximum clock frequency that can be used is equal to ______kHz.

• A. 250

Answer 1

The correct option is A 250
$T_c=n{t}_{pd}$
$f_c=\frac{1}{T_c}=\frac{1}{n{t}_{pd}}$
$n=8$
$t_{pd}=500ns$
$\therefore f_c=\frac{1}{8\times 500\times {10}^{-9}}=250\text{kHz}$