Silicon PPA and closure impact

Shared impedance and package effects often dominate final AMS behavior.

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 — Package Effects on AMS
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 — Package Effects on AMS

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

AMS signoff is a combined noise, IR, timing, and package decision.

Concept diagram

BOUNDARY SIGNOFF

noise + IR + package + timing -> release decision

Metric graph

RISK DASHBOARD

open blockers █████
waivers       ███

Reports and artifacts

• supply ripple spectrum

• IR around analog islands

• package PI summary

• release dashboard

Mini case study

IR hotspot at analog island caused jitter spikes only under burst traffic.

Debug branches

• Correlate droop and jitter

• Check package return path

• Validate mode-specific activity profile

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

Bump assignments, return-current loops, and package resonances alter reference quality and high-speed channel behavior seen by mixed-signal interfaces.

Metric: package-induced jitter, return-path discontinuity flags, board bring-up instability