What is an RC corner?
From PDVerse MMMC Interview Masterclass · pdVerse Mentor Series
Direct answer
An RC corner is a named, characterized interconnect condition — a set of assumptions about wire resistance and capacitance — used consistently across the flow. If the timing library describes how the cells behave, the RC corner describes how the wires between them behave.
Mentor explanation
Cells and wires are two completely separate physics problems, and MMMC keeps them as two separate objects for exactly that reason. The timing library assumes a PVT point and tells you cell delay. The RC corner assumes an interconnect condition and tells you (through extraction) net delay and how much a signal's edge degrades as it crosses that net. You need both, together, to describe one complete timing environment for a path that has cells and wires in series.
Interview trap
Assuming an RC corner named something like "RCmax" is automatically the setup-critical one. The name is methodology-defined, not a mathematical guarantee.
Key takeaways
- An RC corner is a named, characterized interconnect condition — a set of assumptions about wire resistance and capacitance — used consistently across the flow.
- If the timing library describes how the cells behave, the RC corner describes how the wires between them behave.
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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