(a) What is the maximum clock frequency that can be used with the counter of Problem 7-5?

(b) What would f_max be if the counter were expanded to six bits?

Data from Problem 7-5

A four-bit ripple counter is driven by a 20-MHz clock signal. Draw the waveforms at the output of each FF if each FF has t_pd = 20 ns. Determine which counter states, if any, will not occur because of the propagation delays.