1,000+ ASIC Interview Questions: SystemVerilog, UVM & RTL

DescriptionQ418

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Q418FWMetaASIC interview problem

Fleet reliability release gate

TechniquesSiliconReliabilityFleet telemetryNormalization

DifficultyHard

TopicPost-Silicon Validation

LanguagePython

Requirements4 checkpoints

Problem

A release passes only when corrected errors are at most 20 per million device-hours and uncorrected errors are at most 0.5 per billion device-hours. Calculate both normalized rates and the decision for three populations.

Starting declarationPython

corrected_rate = corrected / hours * 1e6
uncorrected_rate = uncorrected / hours * 1e9
pass only if both inclusive thresholds are met

Example input and output

Use this case to check your interpretation

Input

Population B: 1e9 hours, 10000 corrected, 1 uncorrected

Output

10 corrected per million hours, 1 uncorrected per billion hours, FAIL

Explanation

The corrected rate passes 20, but the uncorrected rate exceeds 0.5; both gates must pass.

Requirements (4)

Use total device-hours as the exposure denominator and decimal million and billion scaling.
Treat a rate equal to its threshold as passing and a rate above either threshold as failing.
Report both rates before the decision even when the first rate fails.
Evaluate A=(2e9 h,30000 corrected,0 uncorrected), B=(1e9 h,10000,1), and C=(5e8 h,15000,0).