Cellular automata based deterministic self-test strategies for programmable data paths

In this paper, novel and optimized test strategies are presented for the generation of a set of predetermined test vectors on chip to be used as part of a BIST strategy for complex programmable data paths. Starting from a set of faults and a corresponding set of test vectors that cover these faults, the corresponding self-test hardware is determined automatically. For this purpose, a cellular automaton has been made. The CAD tool CAST accomplishes the synthesis of the cellular automaton and the self-test control logic, and evaluates the solution obtained. Dedicated test strategies for 1-pattern tests on the one hand and 1- and 2-pattern tests on the other hand have been developed. These new optimized strategies guarantee a BIST implementation with 100% stuck-at and stuck-open/close fault coverage for all detectable faults. They have been applied to data paths as used in an industrial-size speech processing vocoder design, developed with the silicon compiler CATHEDRAL-II