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High-Speed SI Awareness: Step-by-Step Walkthrough

Step-by-Step Walkthrough for High-Speed SI Awareness.

Step-by-step analysis walkthrough

Use this when you own High-Speed SI Awareness 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

  • channel compliance report, lane margin scan, SI waiver sheet

  • handoff contract

  • firmware/config tag

  • physical signoff snapshot

  • decision memo

Decision memo template

diagram
AMS DECISION MEMO — High-Speed SI Awareness
mode/condition:
metric:
hypothesis:
fix:
regression:
owners: package owner, SI/PI owner, SerDes integration owner

Reference visuals

Channel SI awareness

diagram
package + board discontinuities -> eye closure/jitter -> retries/link drops
digital symptoms often originate in electrical margin.

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

At multi-Gbps speeds, package/channel discontinuities and return-path quality convert into jitter and eye closure that appear as digital protocol instability.

Metric: SI-induced retries, lane margin, intermittent link drop rate

Practice this lesson