DenseChip

AMS Interface · All levels

Equalization Overview: Step-by-Step Walkthrough

Step-by-Step Walkthrough for Equalization Overview.

Step-by-step analysis walkthrough

Use this when you own Equalization Overview during an AMS war room.

  1. Capture failing mode and environmental condition.

  2. Pull synchronized waveform, logs, and report artifacts.

  3. Mark first boundary where legal behavior diverges.

  4. Audit reset/clock/power sequence assumptions.

  5. Check physical coupling contributors (floorplan/power/package) where relevant.

  6. Assign single-thread ownership for the first fix.

  7. Propose bounded change and define success criterion.

  8. Run scenario and safety regressions.

  9. Document findings in closure memo.

  10. Update signoff dashboard and waiver state.

Artifacts to collect

  • EQ sweep report, eye diagram snapshot, adaptation log

  • handoff contract

  • firmware/config tag

  • physical signoff snapshot

  • decision memo

Decision memo template

diagram
AMS DECISION MEMO — Equalization Overview
mode/condition:
metric:
hypothesis:
fix:
regression:
owners: SI owner, SerDes owner, validation engineer

Reference visuals

Equalization tradeoff

diagram
EQ too low  -> ISI dominates -> BER rises
EQ optimal  -> eye opens -> BER minimum
EQ too high -> noise amplified -> BER rises

AMS deep dive

SerDes closure requires protocol, training, and SI evidence together.

Concept diagram

diagram
SERDES FLOW

training -> equalization -> lane margin -> protocol stability

Metric graph

diagram
BER VS EQ

BER
 ^
 |  high  low  high
 +-----------------> EQ setting

Reports and artifacts

  • lane BER

  • training state transitions

  • EQ sweep report

  • link retry counters

Mini case study

Link looked protocol-clean but lane margin collapsed under thermal sweep.

Debug branches

  • Correlate LTSSM and lane metrics

  • Check SI margins

  • Review firmware timeout assumptions

Senior review question

Ask: what boundary condition proves this topic is actually closed?

Key takeaways

  • State boundary, mode, and evidence tag with every claim.

  • Always align analog, digital, and physical owners before signoff decisions.

Common pitfalls

  • Fixing averages while tails still fail.

  • Skipping package/supply evidence in jitter or SerDes issues.

  • Shipping with waivers that lack owner and expiration criteria.

Principal AMS review addendum

TX pre-emphasis and RX equalization compensate ISI and channel loss; over/under-equalization shifts noise sensitivity and error distribution.

Metric: eye opening, BER vs EQ setting, adaptation convergence

Practice this lesson