Question

In a 4-bit ripple counter, if the period of the waveform at the last flip-flop is 64 microseconds, then the frequency of the ripple counter in kHz is ______________. {(Answer in integer)}

Hint:

In an n-bit ripple counter, the output frequency of the last flip-flop is given by \( f_{out} = \frac{f_{clk}}{2^n} \).

Answer 1

Correct Answer: 250

A 4-bit counter completes one full output cycle after \(2^4 = 16\) input clock pulses. The given output waveform repeats once every \(64\,\mu s\), which corresponds to the time taken for these 16 pulses.

Therefore, the duration of a single clock pulse is:

\(\dfrac{64\,\mu s}{16} = 4\,\mu s\)

This means the clock produces one pulse every \(4\,\mu s\). Converting this interval into a rate:

\(\dfrac{1}{4 \times 10^{-6}} = 2.5 \times 10^5\,\text{Hz}\)

Hence, the input clock frequency is \(\boxed{250\,\text{kHz}}\).