An alternative method of generating tests for path delay faults using N/sub i/-detection test sets

Abstract

In order to generate tests for path delay faults we propose an alternative method that does not generate a test for each path delay fault directly. The proposed method generates an n-propagation test-pair set by using an N/sub i/-detection test set for single stuck-at faults. The n-propagation test-pair set is a set of vector pairs which contains n distinct vector pairs for every transition fault at a checkpoint (primary inputs and fanout branches in a circuit are called check points). We do not target the path delay faults for test generation, instead, the n-propagation test-pair set is generated for the transition (both rising and falling) faults of check points in the circuit, and simulated to determine their effectiveness for singly testable path delay faults and robust path delay faults. Results of experiments on the ISCAS'85 benchmark circuits show that the n-propagation test-pair sets obtained by our method are very effective in testing path delay faults.