Worst-Case and Average-Case Analysis of n-Detection Test Sets

TL;DR

This paper analyzes how restricting the number of detections per fault affects the coverage of untargeted faults in n-detection test sets, showing that large n may be necessary for complete fault detection.

Contribution

It provides a general, approach-independent analysis of the impact of n on fault coverage, including worst-case and average-case scenarios.

Findings

Large n values may be required for full untargeted fault detection.

Coverage depends heavily on circuit-specific fault sets.

Analysis is independent of specific test generation methods.

Abstract

Test sets that detect each target fault n times (n-detection test sets) are typically generated for restricted values of n due to the increase in test set size with n. We perform both a worst-case analysis and an average-case analysis to check the effect of restricting n on the unmodeled fault coverage of an (arbitrary) n-detection test set. Our analysis is independent of any particular test set or test generation approach. It is based on a specific set of target faults and a specific set of untargeted faults. It shows that, depending on the circuit, very large values of n may be needed to guarantee the detection of all the untargeted faults. We discuss the implications of these results.