STA Mastery · All levels

STA Whiteboard Framework

A reusable structure for timing and signoff interviews.

STA whiteboard flow

diagram

1. Draw launch FF -> logic -> capture FF.
2. Mark launch and capture clock edges.
3. Write setup inequality (arrival vs required).
4. Note corner/mode/view and path group.
5. Split cell vs net delay on critical path.
6. List constraint checks (generated clock, false path, IO).
7. Propose ECO + hold + MMMC regression.

Key takeaways

Strong answers always include scenario context with slack numbers.
Never propose ECO without hold and regression plan.

STA deep dive

STA signoff requires reproducible constraints, views, and scenarios.

Concept diagram

diagram

constraints -> graph -> slack

Metric graph

diagram

WNS trend

Reports and artifacts

WNS
TNS
hold WNS

Mini case study

Tag every database.

Debug branches

Check constraints first

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.

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