Silicon PPA and closure impact

Clocking quality and supply behavior shift real converter validity windows.

Area drivers

• Boundary cells and guards add area

• Routing keepouts can increase utilization pressure

Power drivers

• Added margins cost power

• Jitter/noise mitigation can increase static and dynamic budgets

Timing impact

• Jitter and uncertainty consume timing

• IR/noise shifts practical timing margin

PD consequences

• Keepouts and strap topology alter congestion and CTS paths

• Package constraints affect lane routing

Verification burden

• Need aligned AMS + digital + package evidence

• Waiver discipline is mandatory

PPA — Data Validity Debug
area/power/timing/closure-time tradeoff

PPA takeaways

• Mixed-signal fixes are multi-objective

• Signoff is cross-team, not single-report

Design option PPA snapshot

BEFORE / AFTER — Data Validity Debug

health score
  ^
  |                     --- target
  |         o regressed
  |               o before fix
  |                    o after bounded fix
  +--------------------------------------> debug iteration

Prove signal quality, timing margin, and integration safety together.

AMS deep dive

Wrapper and sampling contracts determine data trustworthiness.

Concept diagram

CONVERTER DATA FLOW

sampling clock -> wrapper -> sync boundary -> system consumer

Metric graph

INVALID SAMPLE BURSTS

time --->  _|¯¯|__|¯¯¯|____|¯|_

Reports and artifacts

• sample validity ratio

• calibration convergence

• CDC audit

• overflow/stale sample counters

Mini case study

Mode transition changed sample phase and invalidated wrapper framing assumptions.

Debug branches

• Sample timing contract

• Calibration hook behavior

• Wrapper CDC integrity

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

Data validity must combine framing correctness, saturation/overflow signaling, and synchronization sanity so software trusts converter samples.

Metric: invalid sample bursts, clipping incidents, stale-data escapes