Test Propagation Through Modules and Circuits

Abstract

Test generation performance can be improved significantly over conventional techniques by combining precomputed module tests to form a test for a complete circuit. We introduce a theory of propagation for modules and circuits which can be used for hierarchical test generation and design for testability. The propagation characteristics of a module - whether it can be sensitized to propagate some or all possible fault effects on an input bus - are represented by structures called ambiguity sets. Algebraic operations are performed on ambiguity sets to determine the propagation characteristics of multi-module circuits. We show how this propagation theory is used in test generation and also to aid in designing circuits suitable for high-level test generation.