Counter families — is a ripple counter asynchronous? Identify whether a ripple counter is, by definition, an asynchronous counter, considering how its stages are clocked.

Introduction / Context:
Terminology in digital design can be confusing early on. “Ripple counter” and “asynchronous counter” are commonly used interchangeably. This item checks whether you recognize that both names describe the same clocking approach and corresponding timing implications.

Given Data / Assumptions:

• Ripple counters clock only the first stage from the external clock.
• Later stages are clocked by the output transitions of preceding flip-flops.
• Non-zero propagation delay exists for each stage.

Concept / Approach:
Because each stage waits for the previous stage to toggle before it sees an effective “clock,” a chain of delays propagates. This is asynchronous operation: not all flip-flops are triggered by the same global clock edge. The ripple of state changes causes skew and potential decoding glitches, placing an upper bound on speed relative to synchronous counters, which clock all stages simultaneously.

Step-by-Step Solution:

Verification / Alternative check:
Standard texts label mod-N counters built from cascaded T or JK flip-flops (toggled by the previous stage) as asynchronous; timing diagrams show sequential rather than simultaneous transitions, confirming asynchronicity.

Why Other Options Are Wrong:

• Incorrect: Contradicts conventional definitions.
• Only true for 4-bit designs: Bit-width is irrelevant.
• Valid at low frequencies only: Frequency affects reliability, not the definition.
• Depends on master clock duty cycle: Duty cycle does not change clock distribution topology.

Common Pitfalls:
Assuming “asynchronous” means “no clock at all”; ignoring hazards when decoding ripple counts at intermediate transitions.

Final Answer:
Correct