IntermediateQuestion 7 of 10Source page 13

Walk through how you'd debug one unexpected timing violation.

From PDVerse MMMC Interview Masterclass · pdVerse Mentor Series

Direct answer

Start from the environment, not the cell. Confirm which view or scenario is failing, then work outward: is the mode correct, is the SDC correct, is the library/PVT correct, is the RC/parasitic data correct, is variation handled consistently — and only after all of that checks out do you look at the physical path itself.

Mentor explanation

The instinct under pressure is to jump straight to the failing path and start resizing or buffering. That's backwards. If the environment producing the violation is wrong — wrong SDC loaded, wrong library paired in, stale or missing parasitics — then any physical fix you make is solving the wrong problem, and it might even make a correctly-configured view worse later. The senior habit is to validate the question before you try to answer it.

Example or conceptual chain

Negative slack -> identify view/scenario -> validate mode and SDC -> validate library/PVT -> validate RC/parasitics -> align variation/SI -> inspect the physical path.

Key takeaways

  • Start from the environment, not the cell.
  • Confirm which view or scenario is failing, then work outward: is the mode correct, is the SDC correct, is the library/PVT correct, is the RC/parasitic data correct, is variation handled consistently — and only after all of that checks out do you look at the physical path itself.
Visual explanationMMMC context: Walk through how you'd debug one unexpected timing violation.
MMMC context: Walk through how you'd debug one unexpected timing violation.A three-step concept map summarizes the focus, core answer, and practical verification for Walk through how you'd debug one unexpected timing violation.Question focusWalk through how you'ddebug one unexpectedtiming violation.Core answerStart from theenvironment, not thecell. Confirm which viewor scenario…Verify in practiceValidate the configuredview, active objects,and report context.Understand → explain the mechanism → verify the assumptions
Self-check: can you answer this aloud?

Try a 45-second answer using this structure:

  1. State the direct answer.
  2. Explain the timing or physical reason.
  3. Name one caveat.
  4. Say how you would verify it in a real flow.

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