Master–slave flip-flops: With a master–slave configuration, is data sampled on the leading edge of the clock while the output updates on the trailing edge?

Introduction / Context:Master–slave flip-flops are built from two latches clocked on opposite phases. This architecture helps prevent race-through by ensuring that data is captured first and then transferred to the output in a controlled sequence. Understanding which edge performs sampling versus output transfer is key for timing analysis in sequential logic.

Given Data / Assumptions:

• Master latch is enabled on the leading (e.g., rising) edge or level; slave on the trailing (e.g., falling) edge or complementary phase.
• Clocking is non-overlapping so both latches are not transparent simultaneously.
• Setup and hold times must be met at the master input.
• Propagation occurs from master to slave at the opposite edge.

Concept / Approach:In a positive-edge–controlled master–slave flip-flop, the master captures input data at the leading edge or when the clock goes HIGH (depending on the implementation), then the slave transfers that captured data to the output at the trailing edge or when the clock goes LOW. The result is an effective edge-triggered device whose output updates once per clock cycle, avoiding level-sensitive transparency during the active phase.

Step-by-Step Solution:

Verification / Alternative check:Timing diagrams in textbooks and datasheets confirm that for positive-edge master–slave designs, the output changes on the opposite (trailing) edge. Similarly, negative-edge master–slave devices invert the edge roles but preserve the capture-then-transfer sequencing.

Why Other Options Are Wrong:

Common Pitfalls:Violating setup/hold at the master input; overlooking clock overlap that momentarily enables both latches; assuming master–slave behaves like two independent latches rather than an integrated edge-triggered device.

Final Answer:Correct