# Counter Implementation and Applications MCQ’s

This set of Digital Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Counter Implementation and Applications”.

1. A 5-bit asynchronous binary counter is made up of five flip-flops, each with a 12 ns propagation delay. The total propagation delay (tp(tot)) is ________
a) 12 ms
b) 24 ns
c) 48 ns
d) 60 ns

2. A 4-bit ripple counter consists of flip-flops, which each have a propagation delay from clock to Q output of 15 ns. For the counter to recycle from 1111 to 0000, it takes a total of ________
a) 15 ns
b) 30 ns
c) 45 ns
d) 60 ns

3. A ripple counter’s speed is limited by the propagation delay of ____________
a) Each flip-flop
b) All flip-flops and gates
c) The flip-flops only with gates
d) Only circuit gates

4. A ripple counter’s speed is limited by the propagation delay of __________
a) Each flip-flop
b) All flip-flops and gates
c) The flip-flops only with gates
d) Only circuit gates

5. The main drawback of a ripple counter is that __________
a) It has a cumulative settling time
b) It has a distributive settling time
c) It has a productive settling time
d) It has an associative settling time

6. As the number of flip flops are increased, the total propagation delay of __________
a) Ripple counter increases but that of synchronous counter remains the same
b) Both ripple and synchronous counters increase
c) Both ripple and synchronous counters remain the same
d) Ripple counter remains the same but that of synchronous counter increases

7. What is the maximum delay that can occur if four flip-flops are connected as a ripple counter and each flip-flop has propagation delays of tPHL = 22 ns and tPLH = 15 ns?
a) 15 ns
b) 22 ns
c) 60 ns
d) 88 ns

8. A 4 bit modulo-16 ripple counter uses JK flip-flops. If the propagation delay of each flip-flop is 50 nsec, the maximum clock frequency that can be used is equal to __________
a) 20 MHz
b) 10 MHz
c) 5 MHz
d) 4 MHz

9. A reliable method for eliminating decoder spikes is the technique called ________
a) Strobing
b) Feeding
c) Wagging
d) Waving

10. Assume a 4-bit ripple counter has a failure in the second flip-flop such that it “locks up”. The third and fourth stages will __________
a) Continue to count with correct outputs
b) Continue to count but have incorrect outputs
c) Stop counting
d) Turn into molten silicon

11. A glitch that appears on the decoded output of a ripple counter is often difficult to see on an oscilloscope because of __________
a) It is a random event
b) It occurs less frequently than the normal decoded output
c) It is very fast
d) All of the Mentioned