Random Pattern Testability

A major problem in self testing with random inputs is verification of the test quality, i.e., the computation of the fault coverage. The brute-force approach of using full-fault simulation does not seem attractive because of the logic structure volume, and the CPU time encountered. A new approach is therefore necessary. This paper describes a new analytical method of computing the fault coverage that is fast compared with simulation. If the fault coverage falls below a certain threshold, it is possible to identify the ``random-pattern-resistant´´ faults, modify the logic to make them easy to detect, and thus, increase the fault coverage of the random test.