Multifault and delay-fault testability of multilevel circuits

Abstract

This paper investigates the relationship between test sets for multiple stuck-at faults and robust path-delay-fault tests in multilevel combinational circuits. It is shown that, in multilevel circuits, a complete robust path-delay-fault test set may not detect all multiple stuck-at faults. We also show that the detectability of the former does not imply the detectability of the latter, as suggested in a recent paper. The presence of undetectable or untested multiple stuck-at faults may invalidate some path delay tests.