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STA Mastery · All levels

View Mismatch Triage: Step-by-Step Walkthrough

Step-by-Step Walkthrough for View Mismatch Triage.

Step-by-step analysis walkthrough

Use when you own View Mismatch Triage in a timing war room.

  1. Open signoff scenario list — note worst WNS corner.

  2. report_timing -max/-min on failing group.

  3. Trace launch and capture clocks on critical path.

  4. Check exceptions and generated clocks on path.

  5. Break down cell vs net delay.

  6. Compare implementation vs signoff view if delta suspicious.

  7. Assign owner: RTL, synth, PD, CTS, SI.

  8. Propose ECO with hold/SI check plan.

  9. Run regression matrix.

  10. Update closure dashboard and memo.

Artifacts to collect

  • view diff report, SPEF metadata, run comparison script

  • SDC file

  • SPEF tag

  • MMMC scenario list

  • ECO ticket

Decision memo template

diagram
STA DECISION MEMO — View Mismatch Triage
corner/mode:
WNS/TNS:
hypothesis:
ECO:
regression:
owners: STA owner, extraction owner, CAD owner

Reference visuals

Run diff checklist

diagram
COMPARE TWO STA RUNS
same?  netlist tag
same?  SDC tag
same?  SPEF tag / corner
same?  lib corner map
same?  tool version
first NO -> explain slack delta

STA deep dive

Debug hygiene separates senior STA leads from report readers.

Concept diagram

diagram
DEBUG ORDER

1. same tags?  2. constraints?  3. view?  4. real path?  5. ECO

Metric graph

diagram
ROOT CAUSE MIX (typical)

constraint bugs  ████████  35%
view mismatch    ██████    25%
real path        ██████    25%
methodology      ████      15%

Reports and artifacts

  • run manifest

  • SDC diff

  • SPEF tag

  • scenario isolation

Mini case study

Mystery regression: SPEF corner tag typo in run script — not a design bug.

Debug branches

  • Manifest every run

  • War room by path group

Senior review question

Ask: what corner/mode/view proves this topic is closed or failing?

Key takeaways

  • State corner, mode, view, and database tag with every slack claim.

  • Run setup and hold plus MMMC regression after every ECO.

Common pitfalls

  • Comparing STA runs with different SPEF or SDC tags.

  • Broad false_path to green-wash violations.

  • Setup-only ECO without hold check.

Principal STA review addendum

Different SPEF, RC corners, or parasitic modes between runs explain apparent regressions without any design change.

Metric: slack delta between views, SPEF tag mismatch count

Practice this lesson