Propagation delay definitions — meaning of tPLH for flip-flop outputs Determine whether the statement is correct: “tPLH is measured from the triggering edge of the clock to the LOW-to-HIGH transition at the output.”

Introduction / Context:Manufacturers specify timing with two complementary propagation delays: tPLH (low-to-high) and tPHL (high-to-low). For clocked devices such as flip-flops, these delays are measured from the active clock edge to the resulting transition at Q. Understanding these labels is crucial for timing closure and clock-speed calculations.

Given Data / Assumptions:

• An edge-triggered flip-flop is clocked by a defined active edge.
• tPLH corresponds to an output change from logic 0 to logic 1.
• Timing is measured to the 50% crossing of input and output waveforms unless otherwise stated in the datasheet.

Concept / Approach:tPLH is the time interval between the reference instant (typically the 50% point of the triggering clock edge) and the 50% point of the output's rising transition. Similarly, tPHL is measured for a falling output transition. These metrics quantify the internal response time and help compute data-path delays and setup/hold slacks in synchronous systems.

Step-by-Step Solution:Identify the triggering clock edge (rising or falling by device specification).Mark the reference (50%) crossing of that edge as t=0.Observe the output transition; if it is LOW→HIGH, measure to its 50% point.The measured interval is tPLH, by definition.

Verification / Alternative check:Consult any standard logic family datasheet: the timing diagrams label tPLH/tPHL exactly as described, for both combinational and sequential devices.

Why Other Options Are Wrong:“Incorrect” misstates the conventional definition. “Only for asynchronous inputs” is wrong; the measurement reference is the clock edge, not asynchronous input changes. “Only for combinational gates” is false; the same naming convention applies to clocked devices with the clock edge as reference.

Common Pitfalls:Confusing which transition (output or input) the L/H refers to; measuring from wrong reference points; ignoring clock-to-Q differences among families.

Final Answer:Correct