CDC / RDC · All levels

CDC Tool Flow

CDC Signoff Methodology: Robust CDC signoff combines structural analysis, protocol checks, reset analysis, and targeted formal/simulation evidence with consistent setup tagging.

What this topic teaches

CDC Tool Flow focuses on closing CDC/RDC risk with mechanism-level reasoning. Robust CDC signoff combines structural analysis, protocol checks, reset analysis, and targeted formal/simulation evidence with consistent setup tagging. Senior signoff depends on proving behavior with targeted evidence, not just clearing tool warnings.

The senior-engineer question

When analysis runtime, violation classification completeness, delta noise between runs regresses, can you classify the hazard, identify accountable owners, and choose the smallest fix or waiver backed by evidence?

diagram

CDC/RDC SIGNOFF FLOW — CDC Tool Flow

crossing inventory + reset map
          |
          v
crossing classification (level/pulse/bus/reset)
          |
          v
structure + protocol + reset checks
          |
          v
critical issues + waiver review
          |
          v
fix / validate / regress / signoff

Picture the crossing behavior

Draw the behavior before touching tools. These visuals are the expected whiteboard baseline for reviews and interviews.

CDC signoff stack

diagram

structural CDC scan
    + protocol assertions
    + reset-domain analysis
    + waiver review gate
    = signoff decision

Crossing sequence

diagram

CROSSING FLOW — CDC Tool Flow

source clock domain -> launch signal -> crossing structure -> destination sample
      |                    |                 |                    |
   source FF           protocol           sync / fifo         destination FF

Key metric: analysis runtime, violation classification completeness, delta noise between runs

Ownership layers

diagram

CDC/RDC OWNERSHIP LAYERS — CDC Tool Flow

layer                 owns                            common failure
------------------    -----------------------------   -----------------------------
design intent         crossing architecture           wrong topology selected
protocol semantics    req/ack, fifo, ordering        liveness/deadlock bugs
reset behavior        assert/deassert sequencing      boot instability
analysis setup        tool rules + waivers            false confidence
signoff governance    risk acceptance + dashboard     stale critical waivers

Evidence to collect

Primary metric: analysis runtime, violation classification completeness, delta noise between runs.
Primary artifact: tool run manifest, CDC config files, violation triage sheet.
Owners to involve: CDC lead, CAD owner, verification owner.
At least one reproducer tied to mode/reset/traffic context.
Decision record: fix, waive, or escalate with rationale.

Ownership map

diagram

OWNERSHIP MAP — CDC Tool Flow

artifact                  owner
----------------------    -------------------------
design intent           CDC lead
verification evidence   CAD owner
signoff decision        verification owner

Every open CDC/RDC issue needs one accountable owner before waiver or fix.

Subpages in this topic

Each topic includes mechanism, I/O contract, metrics, debug, worked example, pitfalls, interview drills, checklist, theory, design tradeoffs, expanded case study, walkthrough, comparison matrix, software view, and silicon impact.

Key takeaways

Classify crossing/reset hazards before proposing fixes.
Pair structural results with protocol/reset behavioral proof.
Treat waivers as bounded risk contracts, not cleanup shortcuts.

Common pitfalls

Mass-waiving warnings near tapeout.
Assuming local IP cleanliness guarantees SoC behavior.
Skipping reconvergence and reset stress after CDC fixes.

CDC/RDC deep dive

Signoff is an evidence governance problem across teams.

Concept diagram

diagram

CDC SIGNOFF LOOP

analysis -> triage -> fix/waive -> review gate -> dashboard

Metric graph

diagram

CRITICAL OPEN COUNT

week1 34
week2 22
week3 10
week4 0

Reports and artifacts

critical by owner
waiver quality
review gate status
closure trend

Mini case study

Pass rates improved while critical waivers aged out of policy; dashboard exposed hidden risk.

Debug branches

Separate quality from quantity metrics
enforce waiver expiry
run gate checklists consistently

Senior review question

Ask: what evidence proves this risk is closed for silicon, not just tool-clean?

Key takeaways

State crossing class, assumptions, and owner with every issue.
Run structural and dynamic regressions after each fix.

Common pitfalls

Treating all warnings as equivalent risk.
Waiving issues without containment evidence.
Skipping reset and reconvergence stress after CDC fixes.

Practice this lesson