(a) Construct a 4-bit up/down counter that uses a Gray-code counting sequence.

(b) Repeat Problem 6-9 by comparing the numbers of changing inputs and outputs on the Gray-code counter to a 4-bit regular synchronous binary counter and a 4-bit ripple counter.

Problem 6-9

For the CMOS logic family, the power consumption is proportional to the sum of the changes from 1-to-0 and 0-to-1 on all gate inputs and outputs in the circuit. When designing counters in very low-power circuits, ripple counters are preferred over regular synchronous binary counters. Carefully count the numbers of changing inputs and outputs, including those related to the clock for a complete cycle of values in a 4-bit ripple counter versus a regular synchronous counter of the same length. Based on this examination, explain why the ripple counter is superior in terms of power consumption.