A test methodology for core-based system LSls

In this paper, we propose a test methodology for core-based system LSIs. Ou r test methodology aims to decrease testing time for core-based system LSIs . In our method, every core is supplied with several sets of test vectors. Every set of test vectors guarantees sufficient fault coverage. Each set of test vectors consists of two parts. One is based on built-in self-test (BI ST) and the other is based on external testing. These sets of test vectors are designed to have different ratio of BIST to external testing each other for every core. We can minimize testing time for core-based system LSIs by selecting from the given sets of test vectors for each core. The main cont ributions of this paper are summarized as follows. (i). BIST is efficiently combined with external testing to relax the limita tion of the external primary inputs and outputs. (ii). External testing for one of cores and BISTs for the others are perfor med in parallel to reduce the total testing time. (iii). The testing time minimization problem for core-based system LSIs is formulated as a combinatorial optimization problem to select the optimal se t of test vectors from given sets of test vectors for each core.