VT Mix Strategy: Reports & Metrics

Reports and metrics

Reports & Metrics for VT Mix Strategy focuses on HVT/SVT/LVT cell mix, setup/hold slack distribution, leakage budget. The goal is to connect observed QoR movement to mechanism, ownership, and regression risk.

A report is useful only when it supports decisions. For VT Mix Strategy, read metric movement with baseline context and expected budget.

Metric movement

QOR TREND — VT Mix Strategy

metric quality
  ^
  |                      target band
  |                o  o  o
  |            o
  |      o  regression
  +----------------------------------> synthesis iteration
   baseline    tuning     signoff-ready

Track: HVT/SVT/LVT cell mix, setup/hold slack distribution, leakage budget

• Track HVT/SVT/LVT cell mix, setup/hold slack distribution, leakage budget with exact run manifests.

• Keep timing/area/power side-by-side in review dashboards.

• Require one-sentence mechanism hypothesis for every major delta.

• Store before/after artifacts with owner signoff.

Synthesis deep dive

PPA closure is a constrained tradeoff problem, not a timing-only exercise.

Concept diagram

PPA TRIAD

timing target <-> power budget <-> area cap

Metric graph

PARETO PROGRESSION

early runs      o o
balanced point    o
over-tuned          o (risk)

Reports and artifacts

• VT mix

• leakage trend

• dynamic power trend

• PPA Pareto table

Mini case study

LVT-heavy fix recovered setup but violated leakage target; balanced VT strategy closed both.

Debug branches

• Timing-only claims need power check

• Validate hold on VT swaps

• Use Pareto memo

Senior review question

Ask: what evidence proves this QoR move is real and stable?

Key takeaways

• State exact run context (RTL, SDC, libs, switches) with every QoR claim.

• Re-run timing, area, and power regressions after each synthesis ECO.

Common pitfalls

• Comparing runs with mismatched constraints or library views.

• Timing-only fixes that violate power or area budgets.

• Skipping equivalence checks after structural changes.

Report reading lens