AMS Floorplan Keepouts: Debug Playbook

Debug playbook

Debug Playbook for AMS Floorplan Keepouts focuses on keepout violation count, analog disturbance incidents, ECO rework. The goal is to connect observed symptom to boundary mechanism, ownership, and signoff risk.

AMS debug is a hunt for first divergence, not downstream symptom management. Most costly delays come from wrong-owner first actions.

Root-cause tree

ROOT-CAUSE TREE — AMS Floorplan Keepouts

keepout violation count, analog disturbance incidents, ECO rework regressed
        |
same silicon / run tags?
   /            \
 no              yes
 |                |
env mismatch    boundary contract or
tag mismatch    true physical issue
 /   \             |
clk   reset      isolate first failing
map   sequence   boundary transition

1. Freeze reproducer: mode, firmware/config, and evidence tags.

2. Find the first boundary signal that diverges.

3. Map divergence to contract clause and owner.

4. Classify failure: contract, sequencing, coupling, package, or tool-view mismatch.

5. Prove mechanism with one reduced reproducer.

6. Apply smallest reversible fix and rerun cross-domain regressions.

Review memo template

STAFF AMS REVIEW MEMO — Mixed-Signal Integration / AMS Floorplan Keepouts

1. Symptom
   - Watched metric: keepout violation count, analog disturbance incidents, ECO rework
   - Failing mode/condition: <power/clock/temp/workload>
   - Boundary under suspicion: <macro/wrapper/interface/lane/island>
   - Repro setup: <sim/emulation/lab + firmware/config tags>

2. Mechanism hypothesis
   - Primary mechanism: Keepout regions protect analog blocks from aggressor routing, switching clusters, and noisy clocks that inject disturbance through substrate and supplies.
   - Competing hypothesis: <contract gap, sequencing, physical coupling, package, tooling>
   - Missing evidence: <waveform, report, scope/analyzer capture, dashboard snapshot>

3. Proposed action
   - Minimal reversible change: <RTL/config/layout/policy>
   - Expected metric movement: <delta and conditions>
   - Regression risk: timing, noise, power, performance, compatibility

4. Signoff
   - Re-run artifact: floorplan keepout map, congestion overlay, integration signoff note
   - Required owners: floorplan owner, analog lead, PD lead
   - Final decision: fix, waive with controls, or escalate

AMS deep dive

Physical proximity and boundary rules are functional constraints in AMS SoCs.

Concept diagram

INTEGRATION FLOW

floorplan keepouts -> guard strategy -> abutment policy -> PV signoff

Metric graph

INTEGRATION ESCAPES

layout boundary issues ███████
waiver drift           ████

Reports and artifacts

• keepout violations

• guard-ring checks

• abutment DRC

• mixed-signal PV dashboard

Mini case study

Late macro move violated quiet-zone assumptions and caused intermittent converter noise excursions.

Debug branches

• Review macro adjacency

• Re-check guard assumptions

• Re-run PV with correct deck variant

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

Keepout regions protect analog blocks from aggressor routing, switching clusters, and noisy clocks that inject disturbance through substrate and supplies.

Metric: keepout violation count, analog disturbance incidents, ECO rework