Current Mirrors, Bias Trees, and Bandgap Reference Basics: Reports and Metrics

Reports and metrics

Reports and Metrics for Current Mirrors, Bias Trees, and Bandgap Reference Basics is anchored on Bias-current accuracy and temperature coefficient after mismatch, finite compliance, and trimming assumptions.. Convert observations into mechanism-backed and owner-bound actions.

A useful report explains why behavior moved, not only that behavior moved.

Evidence matrix

EVIDENCE MATRIX - Current Mirrors, Bias Trees, and Bandgap Reference Basics

+-----------------------------+--------------------------------+--------------------------------+---------------------------+
| Evidence                    | Tells you                      | Does not prove                 | Next action               |
+-----------------------------+--------------------------------+--------------------------------+---------------------------+
| setup calibration logs      | measurement chain validity     | mechanism root cause           | pair with transfer checks |
| spectrum and jitter plots   | frequency-domain behavior      | ownership of failure           | correlate with activity   |
| PVT corner overlays         | sensitivity distribution       | runtime workload equivalence   | add workload replay       |
| model-vs-silicon deltas     | assumption mismatch classes    | direct fix correctness         | test bounded mitigation   |
| before-after matrix         | mitigation movement            | long-term field drift          | run stress suites         |
+-----------------------------+--------------------------------+--------------------------------+---------------------------+

• Track Bias-current accuracy and temperature coefficient after mismatch, finite compliance, and trimming assumptions. on representative stress slices.

• Include setup, workload, and environmental metadata in every report.

• Correlate measured movement with source-path-victim assumptions.

• Call out contradictory evidence explicitly.

Analog deep dive

Device and circuit intuition links transistor-level behavior to system-level reliability and calibration burden.

Concept diagram

CIRCUIT REASONING FLOW

device region -> small-signal model -> loop behavior -> integration risk

Metric graph

CIRCUIT RISK MIX

headroom collapse        ████
loop peaking             █████
bias drift               ███

Metrics and artifacts to collect

• operating-region and headroom map

• bias drift and compliance checks

• loop-stability margin report

• offset and hysteresis validation

Mini case study

Nominal functionality hid compliance failures that only appeared under low-voltage corners and realistic load profiles.

Debug branches

• Verify operating region assumptions before topology changes.

• Separate static bias errors from dynamic stability behavior.

• Track where calibration is masking core circuit weakness.

Senior review question

Ask: which source-path-victim boundary failed first, and which artifact proves it reproducibly?

Key takeaways

• Tie every analog claim to one measurable metric and one proving artifact.

• Prefer minimal reversible mitigations with explicit owner and rollback criteria.

Common pitfalls

• Treating all noise as one scalar instead of path and frequency dependent behavior.

• Changing multiple analog knobs at once and losing causality.

• Declaring closure from nominal behavior without stress replay evidence.

Report interpretation

Treat report movement as hypothesis evidence, not final proof.

Cross-check metrics with setup integrity and model assumptions.