Storage-Based Logic Built-in Self-Test With Multicycle Tests

Storing deterministic test data on-chip allows logic built-in self-test (LBIST) to produce a special type of random test that consists of random combinations of deterministic test data. Such tests can achieve a higher fault coverage than random tests whose bits are determined randomly. A bottleneck of this approach is the volume of test data that needs to be stored. This article observes that the use of multicycle tests can address this bottleneck by reducing the number of tests needed for detecting target faults and, thus, the volume of test data needed for producing them. A software procedure is described to support this solution. Experimental results for benchmark circuits demonstrate the effectiveness of multicycle tests in this context.