On n-detection test sequences for synchronous sequential circuits

Abstract

Test sets that detect each stuck-at fault n>1 times (called n-detection test sets) were shown to achieve higher defect coverages than conventional single stuck-at 1-detection test sets. Previous studies of n-detection test sets concentrated on combinational circuits. In this work, we study n-detection test sequences for synchronous sequential circuits. We propose four definitions of the number of detections achieved by a test sequence. We describe fault simulation and test generation procedures based on these definitions, and evaluate them on benchmark circuits by using non-feedback bridging faults to model defects. The results indicate the usefulness of the simplest definition in generating test sequences that achieve improved defect coverages.