Self-repairable GALs

This paper describes the concept of self-testable and self-repairable Generic Array Logic (GAL) devices for high security and safety applications. A design methodology is proposed for self-repairing of a GAL which is a kind of Electrically Programmable Logic Devices (EPLDs). The fault-locating and fault-repairing architecture with electrically re-configurable GALs is presented. It uses universal test sets, fault-detecting logic, and self-repairing circuits with spare devices. The design method allows to detect, diagnose, and repair of all multiple stuck-at faults which might occur on E2CMOS cells in programmable AND plane. A selfrepairing methodology is presented, based on our design architecture. A "column replacement" method with extra columns is introduced that discards each faulty column entirely and replaces it with an extra column. The evaluation methodology proves that a selfrepairable GAL will last longer in the field. It gives also information on how many extra columns a GAL needs to reach a lifetime goal, in terms of simulation looping time, until the GAL is not useful any more. Therefore, an ideal point could be estimated, where the maximum reliability can be reached with the minimum cost.