Fault (in)dependent cost estimates and conflict-directed backtracking to guide sequential circuit test generation

The search for tests for sequential circuits (STPG) by deterministic test pattern generation is a process of alternately performing mandatory assignments and heuristic decisions on signal lines. We have observed problems in the decision-making process due to shortcomings in the SCOAP controllability/observability metrics and the backtrack process during STPG. In this paper we propose new techniques to improve the controllability/observability metrics, and two forms of conflict-directed backtracking (back-jumping) to improve the backtrack process. Experimental results demonstrate that the proposed techniques are very promising and result in a significant improvement in fault efficiencies and CPU usage for the ISCAS´89 and industrial circuits