Electronics Engineering (ELEX) Board Practice Exam

A ripple counter's speed is primarily limited by what factor?

1. Power supply voltage

2. Each flip-flop's propagation delay

3. The clock frequency

4. The load capacitance

The correct answer is: Each flip-flop's propagation delay

In a ripple counter, the speed at which it can operate is primarily influenced by the propagation delay of each flip-flop used in the circuit. Propagation delay refers to the time it takes for a change in input at one flip-flop to cause a change in output. In a ripple counter, the flip-flops are connected in series; therefore, the output of one flip-flop serves as the clock input for the next flip-flop. This configuration means that the total count speed is affected by the cumulative delays of all the flip-flops in the chain. As each flip-flop only toggles its state after receiving a clock pulse and after the previous flip-flop has completed its state change, any delay in the output of a flip-flop directly delays the operation of the subsequent flip-flop. As a result, the overall counting speed is limited by the sum of these propagation delays. Consequently, the ripple counter's performance can be quite slow especially when the number of flip-flops increases, thus limiting its effective frequency of operation. The other factors, such as power supply voltage, clock frequency, and load capacitance, do have roles in circuit performance but are not the primary limiting factors for the speed of a ripple counter. The