On diagnosing path delay faults in an at-speed environment

Recent techniques for path delay fault diagnosis have addressed the problem in combinational circuits and sequential circuits. The root cause of a path delay fault test failure is narrowed down to a set of functionally sensitized paths and this set is further reduced by post processing the set of passing tests. In this paper, we present a method for narrowing down the suspects further to a set of segments on the failing functionally sensitized paths. The proposed method is implemented and applied to a set of industrial circuits and it is found to be very effective in determining the defective segments that explain excessive delays along paths.