Enhanced delay defect coverage with path-segments

The number of robustly testable paths is very low for typical circuits, hence the delay defect coverage of a robust path fault test set can be very small. Robustly testing path-segments which are not covered by any robustly testable paths can enhance the defect coverage of a path test set, however the existence of such uncovered path-segments in benchmark circuits has not been proven so far. In this paper we experimentally prove the existence of robustly testable path-segments not covered by any robustly testable paths in the ISCAS benchmark circuits. A highly effective delay fault test generator using some novel techniques, has been implemented for this purpose and is also described in the paper.