An efficient nonenumerative method to estimate the path delay fault coverage in combinational circuits

A method to estimate the coverage of path delay faults of a given test set, without enumerating paths, is proposed. The method is polynomial in the number of lines in the circuit, and thus allows circuits with large numbers of paths to be considered under the path delay fault model. Several levels of approximation, with increasing accuracy and increasing polynomial complexity, are proposed. Experimental results are presented to show the effectiveness and accuracy of the estimate in evaluating the path delay fault coverage. Combining this nonenumerative estimation method with a test generation method for path delay faults would yield a cost effective method to consider path delay faults in large circuits, which are beyond the capabilities of existing test generation and fault simulation procedures, that are based on enumeration of paths