A Topological Search Algorithm for ATPG

The automatic generation of tests for combinational digital circuits is examined from the standpoint of a guided search through a search space. The limitations of this process, namely the size of the search space and the overall strategy, are identified and methods are presented to reduce the size of the search space as well as produce a more optimal ordering of node assignments. A new algorithm is proposed that uses the smaller search space and the improved ordering for node assignments based on a topological analysis of the circuit. Results are presented indicating that this new algorithm, termed TOPological Search (TOPS), is faster than existing algorithms and also rapidly identifies many redundant faults without search.