Positive edge-triggered D flip-flop capture A positive edge-triggered D flip-flop will store a logic 1 under which timing condition?

Introduction / Context:Edge-triggered flip-flops sample inputs only at a specific clock transition. For a positive edge-triggered device, the LOW-to-HIGH transition is the critical instant. Understanding this sampling instant is essential for meeting setup and hold time constraints and avoiding metastability.

Given Data / Assumptions:

• Device: positive edge-triggered D flip-flop.
• Input: D must be stable around the sampling edge.
• Clock: the active edge is rising (LOW → HIGH).

Concept / Approach:At the rising edge of the clock, the flip-flop captures the logic level present on D (if setup/hold requirements are satisfied). If D = 1 at that instant, Q becomes 1 after the device propagation delay and remains 1 until the next active edge (unless asynchronously overridden by preset/clear signals, if present).

Step-by-Step Solution:

Verification / Alternative check:Timing diagrams show the sampling window centered on the rising edge, with setup/hold slacks specified. Simulations using HDL primitives confirm that Q follows D only on that edge, not during steady clock levels.

Why Other Options Are Wrong:

• HIGH-to-LOW: Describes negative-edge devices.
• Clock LOW or HIGH (steady levels): Edge-triggered devices do not capture simply due to level; they sample on transitions.

Common Pitfalls:Violating setup/hold times, which may cause metastability or incorrect capture, and assuming level-sensitive behavior instead of edge-triggered.

Final Answer:the D input is HIGH and the clock transitions from LOW to HIGH