Max-Fill: A method to generate high quality delay tests

Abstract

It was recently observed that the methods to generate scan based tests with low switching activity cause about 40% less activity than functional tests. Thus such tests may cause test escapes as they may not adequately stress the circuits under test. In this work we propose a method called Max-Fill to generate high quality partially-functional broadside delay tests. The generated tests are shown to cause switching activity close to the switching activity during functional operation. The method computes a set of reachable states in which states are likely to cause high switching activity. During test generation phase, these states are used as background states to fill the unspecified bits of test cubes. Additionally, the number of test patterns produced is less than that produced by low power test methods. Experimental results for ISCAS-89 circuits are given.