Data Validity Debug: Worked Example

Worked example

Worked Example for Data Validity Debug focuses on invalid sample bursts, clipping incidents, stale-data escapes. The goal is to connect observed symptom to boundary mechanism, ownership, and signoff risk.

A stress workload shows invalid sample bursts, clipping incidents, stale-data escapes. The first review mistake is broad blame. A better review tracks one boundary transition, validates contract assumptions, and proves the first failing mechanism in Data Validity Debug.

Sequence under inspection

AMS BOUNDARY SEQUENCE — Data Validity Debug

analog macro -> wrapper / boundary cell -> synchronizer or sampler -> digital consumer
      |                 |                         |                     |
  analog assumptions    legal voltage/state       clock/reset contract   protocol/data validity

metric under watch: invalid sample bursts, clipping incidents, stale-data escapes

Data validity checks

frame valid + saturation flag + sequence integrity + freshness
all must pass before data is trusted.

1. Capture tagged waveform/log/report set.

2. Mark mode boundary and first failure timestamp.

3. Map to contract and owner.

4. Compare against validity checker report, sampled trace set, anomaly triage memo.

5. Propose one reversible fix and predefine regression matrix.

Did the fix work?

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