Asynchronous (ripple) counter timing: simultaneous switching? “In an asynchronous counter, all flip-flops change state at exactly the same time.” Evaluate this timing claim.

Introduction / Context:
Asynchronous counters, also called ripple counters, are simple and popular for low-speed divide-by-N applications. However, their timing differs fundamentally from synchronous counters. This question probes whether all stages switch together in a ripple design.

Given Data / Assumptions:

• Ripple counters chain the clock: one flip-flop’s Q output drives the next stage’s clock.
• Each flip-flop has a finite clock-to-Q propagation delay.
• Signals therefore propagate sequentially from LSB to MSB (or vice versa), not simultaneously.

Concept / Approach:
Because the clock is not common to all stages, transitions appear as a “ripple” through the chain. The LSB toggles first on the external clock edge; subsequent stages toggle only after receiving a (delayed) edge from the prior stage’s output. The visible effect is non-simultaneous switching and transient intermediate codes during transitions.

Step-by-Step Solution:
Identify architecture: asynchronous (ripple) clock chaining.Note finite t_CQ per stage → staggered toggles.Therefore, outputs do not change at exactly the same time.Conclusion: the statement is incorrect.

Verification / Alternative check:
Scope captures show a “stairstep” of output transitions for ripple counters. Data sheets warn about decoding glitches due to intermediate states during transitions.

Why Other Options Are Wrong:
“Correct” contradicts ripple behavior. Frequency does not make transitions simultaneous. Gray coding affects output codes, not clock distribution.

Common Pitfalls:
Using ripple counters in high-speed or glitch-sensitive decode paths; failing to register decoded outputs to remove hazards.

Final Answer:
Incorrect