Q3 Clock (a) Circuit Clock 03 Count 0 12 3 4 5 6 7 8 9 10 11 12 13 14 15 01 (b) Timing diagram Figure 5.21 A fourbit synchronous up counter. (10 points) In class, we have studied synchronous up-counters using toggle-flip-flops (TFFs); also given in Fig. 5.21, Section 5.9.2, in the textbook. Design a 4-bit synchronous down-counter using TFFs and demonstrate the down-counting operation of the circuit