In a 4-bit ripple counter, if the period of the waveform at the last flip-flop…
2025
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)
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Correct answer: 250
Key idea: a 4-bit ripple counter divides the input clock frequency by 2^4 = 16, so the input frequency is 16 times the frequency at the last flip-flop.
Compute the frequency at the last flip-flop: f_last = 1 / T_last = 1 / 64 microseconds = 1 / 64e-6 s = 15,625 Hz.
Compute the input (counter) frequency: f_in = 16 × f_last = 16 × 15,625 Hz = 250,000 Hz = 250 kHz.
Answer: 250 kHz
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