What is a delay corner?
From PDVerse MMMC Interview Masterclass · pdVerse Mentor Series
Direct answer
A delay corner is the combination of a library set (how the cells behave) and an RC corner (how the wires behave) into one unified condition for computing delay. It answers, in one object, "how do cells and wires behave together, right now?
Mentor explanation
Up to this point, cell behavior and wire behavior are two separate stories — one from Liberty, one from extraction assumptions. Neither one alone is enough to compute a path delay, because a real path always alternates between cells and the wires connecting them. The delay corner is the object that says "use this library set for the cells and this RC corner for the wires, together, as one condition." Exactly how this pairing is implemented (its object name and commands) is vendor-specific, so treat the concept as universal and the exact syntax as something you verify per tool.
Example or conceptual chain
Library set (cells) + RC corner (wires) -> delay corner.
Key takeaways
- A delay corner is the combination of a library set (how the cells behave) and an RC corner (how the wires behave) into one unified condition for computing delay.
- It answers, in one object, "how do cells and wires behave together, right now?
Self-check: can you answer this aloud?
Try a 45-second answer using this structure:
- State the direct answer.
- Explain the timing or physical reason.
- Name one caveat.
- Say how you would verify it in a real flow.
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