Dual Use Circuitry for Early Failure Warning and Test

Incorrect circuit timing often leads to errors in the field, including silent data corruption. Once a circuit violates timing, recovery can be difficult even when the violation is detected. Canary flip-flops have previously been proposed to identify when the desired slack of a path has first been violated in functional mode even before failure occurs. We show how such flip-flops can be combined in a MISR to also provide enhanced coverage during manufacturing test and scan-based field test.