Edge-triggered flip-flops — timing of input sampling and output change Judge the statement: “With edge-triggered flip-flops, data enter on the leading clock edge but the output does not change until the trailing edge.”

Introduction / Context:Edge-triggered flip-flops sample inputs at a specific clock transition and then update outputs after a propagation delay referenced to that same edge. The idea that the output waits for the opposite clock edge mixes up edge-triggered behavior with two-phase master–slave latch operation.

Given Data / Assumptions:

• The device is an edge-triggered flip-flop (rising or falling edge).
• Setup and hold times are met around the active edge.
• Clock-to-Q propagation delay (tPLH/tPHL) defines when Q settles after the edge.

Concept / Approach:At the active edge, the flip-flop captures inputs and begins internal transitions. The output reflects the new state after a short delay (nanoseconds), not at the opposite clock edge. Master–slave latches internally use two non-overlapping phases but still present a single-edge interface; the public Q does not wait for the trailing edge in true edge-triggered implementations.

Step-by-Step Solution:Identify the specified active edge (e.g., rising edge).Ensure D/J/K inputs are stable for tSU/tH around this edge.Observe that Q updates after the edge by tPLH/tPHL, completing well before the next opposite edge.Therefore, the statement claiming change only at the trailing edge is incorrect.

Verification / Alternative check:Datasheet timing diagrams show clock-to-Q referenced to the same edge. Simulation with a standard D or J–K flip-flop confirms immediate (delayed) response after the active edge.

Why Other Options Are Wrong:“Correct” contradicts standard timing. “True only for master–slave” and “true only with gated clocks” add conditions that still do not defer Q until the opposite edge in edge-triggered devices.

Common Pitfalls:Confusing transparent latching intervals with edge capture; ignoring propagation delay and thus expecting instantaneous change at the edge.

Final Answer:Incorrect