Inputs and outputs contract

Inputs & Outputs for Scenario: SerDes Bring-up Collapse focuses on L0 bring-up pass rate, BER spikes, retrain frequency. The goal is to connect observed symptom to boundary mechanism, ownership, and signoff risk.

Treat these inputs and outputs as signed interface guarantees. Ambiguity here creates the most expensive integration bugs.

INPUTS
  - AMS handoff contract and spec revision
  - mode definitions (power/clock/reset/traffic)
  - wrapper and boundary-cell assumptions
  - physical constraints: keepouts, guard, package limits

OUTPUTS
  - mode-tagged metric report
  - owner-signed debug or closure note
  - waiver manifest with expiry and controls
  - release recommendation

Boundary sequence

AMS BOUNDARY SEQUENCE — Scenario: SerDes Bring-up Collapse

analog macro -> wrapper / boundary cell -> synchronizer or sampler -> digital consumer
      |                 |                         |                     |
  analog assumptions    legal voltage/state       clock/reset contract   protocol/data validity

metric under watch: L0 bring-up pass rate, BER spikes, retrain frequency

Ownership map

OWNERSHIP MAP — Scenario: SerDes Bring-up Collapse

artifact                  owner
----------------------    -----------------------------
integration artifact    SerDes owner
implementation artifact firmware owner
signoff artifact        validation owner

Every boundary issue needs a named owner before fixes start.

AMS deep dive

Senior interview answers must show mechanism, ownership, and regression discipline.

Concept diagram

INTERVIEW LADDER

symptom -> mechanism -> evidence -> owner -> bounded fix -> regression

Metric graph

ANSWER QUALITY

mechanism depth ██████
evidence usage  █████
ownership clarity ████

Reports and artifacts

• mock interview rubric

• scenario response score

• evidence completeness

• regression-plan quality

Mini case study

Candidate fixed the symptom but failed to define a regression matrix and ownership map.

Debug branches

• Name first failing boundary

• State one proving artifact

• Propose one bounded reversible fix

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

SerDes bring-up failures usually combine training state assumptions, SI margin, and firmware sequencing; diagnosing only one layer misses interaction faults.

Metric: L0 bring-up pass rate, BER spikes, retrain frequency