ECO Physical vs Logical: Inputs & Outputs

Inputs and outputs contract

Inputs & Outputs for ECO Physical vs Logical focuses on ECO turnaround time, leakage delta, area delta, timing recovery. The goal is to connect the observable symptom to timing mechanism, ownership, and regression risk.

Treat these as a signed interface contract. Ambiguity here is the single biggest source of wasted integration weeks, because two teams debug against different assumptions.

INPUTS
  - SDC (clocks, IO delays, exceptions)
  - Liberty libraries per corner
  - SPEF/parasitics and RC corner
  - MMMC scenario definition

OUTPUTS
  - WNS/TNS reports per scenario
  - path group summaries
  - constraint audit / waiver log
  - signoff closure memo

Timing path sequence

TIMING PATH — ECO Physical vs Logical

launch FF --logic stages--> capture FF
     |                           |
  launch clock                capture clock
     |                           |
  required: arrival < capture_edge - setup
  metric: ECO turnaround time, leakage delta, area delta, timing recovery

Ownership map

OWNERSHIP MAP — ECO Physical vs Logical

artifact              owner
----------------      -----------------
timing report       PD owner
SDC/constraint      RTL owner
implementation      STA owner

Every WNS cluster needs a named owner before ECO.

STA deep dive

ECO without regression is a coin flip.

Concept diagram

ECO LOOP

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

Metric graph

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

Logical ECO changes netlist; physical ECO changes placement/routing; each has different cost, risk, and regression surface.

Metric: ECO turnaround time, leakage delta, area delta, timing recovery