28 Lecture

In a synchronous decade counter, how many flip-flops are used? a) 4 b) 6 c) 8 d) 10 Answer: d) 10 What is the maximum count of a synchronous decade counter? a) 5 b) 9 c) 10 d) 16 Answer: c) 10 What is the clock signal frequency required for a synchronous decade counter to count at 1 Hz? a) 1 kHz b) 10 kHz c) 100 kHz d) 1 MHz Answer: b) 10 kHz How many clock cycles are required for a synchronous decade counter to count from 0 to 5? a) 3 b) 5 c) 10 d) 16 Answer: b) 5 What is the purpose of the carry output in a synchronous decade counter? a) to indicate when the counter has reached its maximum count b) to provide a clock signal for the next stage of the counter c) to reset the counter to its initial value d) to enable/disable the counter Answer: b) to provide a clock signal for the next stage of the counter What is the relationship between the clock signal and the flip-flop outputs in a synchronous decade counter? a) they are always in phase with each other b) they are always out of phase with each other c) they are in phase during the count up and out of phase during the count down d) they are out of phase during the count up and in phase during the count down Answer: a) they are always in phase with each other What is the timing relationship between the flip-flop outputs in a synchronous decade counter? a) they change state simultaneously on the rising edge of the clock signal b) they change state simultaneously on the falling edge of the clock signal c) they change state sequentially on the rising edge of the clock signal d) they change state sequentially on the falling edge of the clock signal Answer: c) they change state sequentially on the rising edge of the clock signal What is the timing relationship between the carry output and the flip-flop outputs in a synchronous decade counter? a) the carry output is always one clock cycle ahead of the flip-flop outputs b) the carry output is always one clock cycle behind the flip-flop outputs c) the carry output and the flip-flop outputs change state simultaneously d) the carry output and the flip-flop outputs change state alternately Answer: b) the carry output is always one clock cycle behind the flip-flop outputs What is the maximum frequency of a synchronous decade counter with a 50 ns propagation delay per flip-flop? a) 20 kHz b) 50 kHz c) 100 kHz d) 200 kHz Answer: c) 100 kHz How many clock cycles are required for a synchronous decade counter to count from 9 to 0? a) 1 b) 9 c) 10 d) 20 Answer: c) 10

What is a timing diagram of a synchronous decade counter, and what does it represent? Answer: A timing diagram of a synchronous decade counter is a graphical representation of the timing relationship between the clock signal, the flip-flop outputs, and the counter output. It shows how the counter advances by one on each clock pulse and how the flip-flop outputs change state to reflect the new counter value. It also shows the ripple effect of the carry output from one flip-flop to the next and how this results in a delay in the counter output. How does the timing diagram of a synchronous decade counter differ from that of an asynchronous counter? Answer: The timing diagram of a synchronous decade counter shows that all flip-flops receive the same clock signal and change state simultaneously. In contrast, the timing diagram of an asynchronous counter shows that each flip-flop receives a delayed clock signal from the previous flip-flop, and therefore the flip-flops change state sequentially. How can you use a timing diagram to verify the performance of a synchronous decade counter? Answer: A timing diagram can be used to verify the performance of a synchronous decade counter by comparing the counter output with the expected sequence of values. If the counter output matches the expected sequence, then the counter is functioning correctly. What is the purpose of the carry output in a synchronous decade counter, and how is it represented in the timing diagram? Answer: The carry output in a synchronous decade counter is used to provide a clock signal for the next stage of the counter. It is represented in the timing diagram as a delayed pulse that occurs after the flip-flop outputs have changed state. What is the maximum count of a synchronous decade counter, and how many flip-flops are used to achieve this count? Answer: The maximum count of a synchronous decade counter is 10, and 10 flip-flops are used to achieve this count. How many clock cycles are required for a synchronous decade counter to count from 0 to 5? Answer: 5 clock cycles are required for a synchronous decade counter to count from 0 to 5. What is the timing relationship between the clock signal and the flip-flop outputs in a synchronous decade counter? Answer: The clock signal and the flip-flop outputs are always in phase with each other in a synchronous decade counter. What is the timing relationship between the flip-flop outputs in a synchronous decade counter? Answer: The flip-flop outputs change state sequentially on the rising edge of the clock signal in a synchronous decade counter. What is the propagation delay of a flip-flop, and how does it affect the maximum frequency of a synchronous decade counter? Answer: The propagation delay of a flip-flop is the time it takes for the output to change state after a clock edge. It affects the maximum frequency of a synchronous decade counter because the delay adds up as the clock signal propagates through each flip-flop, limiting the maximum clock frequency that can be used. How can you calculate the maximum clock frequency of a synchronous decade counter given the propagation delay of each flip-flop? Answer: The maximum clock frequency of a synchronous decade counter can be calculated by dividing the minimum propagation delay of the flip-flops by the number of flip-flops used. For example, if each flip-flop has a minimum propagation delay of 20 ns and 10 flip-flops are used, the maximum clock frequency would be 1/(20ns x 10) = 500 kHz.