Derates and margins are the most consequential numbers in a timing setup and the least visible in a report. A value that is too small risks silicon; one that is too large costs area, power and schedule. This topic treats them as a managed policy: values with a source, margins with owners, a measurable cost for excess, and an audit that compares what was intended with what was applied.
Lesson | After it you can... |
|---|---|
Derive a derate from measured variation. | |
Keep a margin ledger with owners. | |
Measure what a little extra derate costs. | |
Check applied values against policy. |
Each margin trades risk against cost, and the people who bear the risk (silicon) and the cost (schedule, area) are different. A policy records who decided and on what evidence.