STA Mastery · All levels

Setup / Hold Closure Order: Step-by-Step Walkthrough

Step-by-Step Walkthrough for Setup / Hold Closure Order.

Step-by-step analysis walkthrough

Use when you own Setup / Hold Closure Order in a timing war room.

Open signoff scenario list — note worst WNS corner.
report_timing -max/-min on failing group.
Trace launch and capture clocks on critical path.
Check exceptions and generated clocks on path.
Break down cell vs net delay.
Compare implementation vs signoff view if delta suspicious.
Assign owner: RTL, synth, PD, CTS, SI.
Propose ECO with hold/SI check plan.
Run regression matrix.
Update closure dashboard and memo.

Artifacts to collect

setup/hold trend chart, ECO sequence log, path replay
SDC file
SPEF tag
MMMC scenario list
ECO ticket

Decision memo template

diagram

STA DECISION MEMO — Setup / Hold Closure Order
corner/mode:
WNS/TNS:
hypothesis:
ECO:
regression:
owners: timing closure lead, PD owner, STA owner

Reference visuals

Setup vs hold tradeoff

diagram

DELAY CHANGE EFFECT

increase cell delay:
  setup slack  improves  (more time before capture)
  hold slack   worsens    (data arrives later vs hold edge)

ECO must check BOTH sides.

STA deep dive

ECO without regression is a coin flip.

Concept diagram

diagram

ECO LOOP

failing path -> fix -> setup check -> hold check -> SI -> MMMC matrix

Metric graph

diagram

ECO PROGRESS

WNS
 0 |              o target
-50|        o
-100|   o baseline
    +-----------------> ECO #

Reports and artifacts

pre/post WNS
hold delta
leakage delta
ECO ticket log

Mini case study

48-hour tapeout crunch: VT swap fixed setup; hold fixed with route on short path — order mattered.

Debug branches

Never ship setup-only proof
Logical ECO needs equivalence

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

Setup and hold compete through delay changes; closure order and ECO type must avoid fixing one at the expense of the other.

Metric: setup WNS, hold WNS, simultaneous violation count

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