Arrangement of latches in scan-path design to improve delay fault coverage

A problem involving the arrangement of latches in a scan-path design to improve the coverage of delay faults is described. The problem is NP-hard, and a heuristic algorithm is introduced for solving this arrangement problem. A necessary and sufficient condition is also given to determine whether there is a scan path to implement a given delay-fault test pair. Only LAM (latch-arrangement-mapping) implementable test pairs need to be simulated by a delay-fault simulator for a semi-completed LSSD (level-sensitive-scan-design) circuit. Preliminary experimental results show that the proposed algorithm can find a LAM with better fault coverage than a randomly selected ones