Question

A 4-bit modulo-16 ripple counter uses JK flip-flops. If the propagation delay of each FF is 50 ns, the maximum clock frequency that can be used is equal to:

• A. 5 MHz
• B. 4 MHz
• C. 10 MHz
• D. 20 MHz

Answer 1

The correct option is A 5 MHz

$f_{clk}$ = $\frac{1}{n{t}_{pdff}}$

= $\frac{1}{4\times 50\times {10}^{-9}}$

$f_{clk}$ = 5MHz {$2^4$ = 16}
{n = 4}