Improving topological ATPG with symbolic techniques

This paper presents a new approach to Automatic Test Pattern Generation for sequential circuits. Traditional topological algorithms nowadays are able to deal with very large circuits, but often fail when highly sequential subnetworks are found. On the other hand, symbolic techniques based on Binary Decision Diagrams proved themselves very efficient on small or medium circuits, no matter their sequential complexity. A state-of-the-art structural ATPG is extended by identifying some critical areas in the circuit and resorting to symbolic techniques when such areas need to be considered. Experimental results prove that the combined approach considerably enhances fault coverage while reducing CPU time when compared to a purely topological approach.