Question

In a 7-stage ripple counter, the propagation delay of a flip-flop is $50ns$. If the pulse width of the strobe pulse is $50ns$, then the maximum frequency at which the counter will operate reliably is

• A. $\text{1.3 MHz}$
• B. $\text{6.3 MHz}$
• C. $\text{2.5 MHz}$
• D. $\text{8.2 MHz}$

Answer 1

The correct option is C $\text{2.5 MHz}$

$f_{max}=\frac{1}{n{t}_{f.f}+t_{strobe}}$
$=\frac{1}{7\times 50+50}\times {10}^9$

$=2.5\times {10}^6\text{Hz}$

$=2.5\text{MHz}$