ATPG tools for delay faults at the functional level

Abstract

We present an ATPG tool for functional delay faults which applies to the single-input transition (SIT) and the multi-input transition (MIT) fault models, and is based on Reduced Ordered Binary Decision Diagrams (ROBDDs). We are able, for the first time, to identify all faults that do not have any SIT tests, and generate all SIT tests for nonredundant faults in combinational circuits. We also provide methodologies for efficient generation of MIT tests. Our experimental results on the ISCAS'85 benchmarks is by far superior to existing methods as well as a Satisfiability-based tool that we have developed for comparative purposes. The presented tool, coupled with advancements in path delay fault coverage, shows that both the SIT and MIT functional models are very useful in ATPG for robust path delay faults for synthesized circuits.