Boundary Cell Design: Step-by-Step Walkthrough

Step-by-step analysis walkthrough

Use this when you own Boundary Cell Design 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

• boundary-cell checklist, level-shifter audit report, reset isolation table

• handoff contract

• firmware/config tag

• physical signoff snapshot

• decision memo

Decision memo template

AMS DECISION MEMO — Boundary Cell Design
mode/condition:
metric:
hypothesis:
fix:
regression:
owners: AMS integration lead, digital implementation owner, library owner

Reference visuals

Boundary cell intent

POWER DOMAIN A -> [level shifter / clamp / isolation] -> DOMAIN B

legal voltage + state crossing is explicit.
missing boundary logic converts into latent silicon risk.

AMS deep dive

Boundary assumptions must be explicit, versioned, and testable.

Concept diagram

BOUNDARY CONTRACT FLOW

analog intent -> boundary implementation -> digital wrapper -> signed review

Metric graph

BOUNDARY RISK MIX

missing boundary cells    ███████
stale handoff assumptions ██████
silent mode changes       ████

Reports and artifacts

• boundary-cell coverage

• isolation/ESD review

• handoff contract checklist

• integration waiver log

Mini case study

Noise bursts traced to missing isolation clamp on one low-power transition mode.

Debug branches

• Validate boundary-cell insertion

• Diff handoff assumptions

• Reproduce with tagged mode sequence

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

Boundary cells protect logic domains at analog interfaces by enforcing voltage tolerance, clamp behavior, and legal signal ownership during power sequencing.

Metric: boundary violation count, level-shifter coverage, clamp correctness