Self-repairable EPLDs: design, self-repair, and evaluation methodology

This paper describes the concept of self-testable and self-repairable EPLDs (Electrically Programmable Logic Devices) for high security and safety applications. A design methodology is proposed for self-repairing of a GAL (Generic Array Logic) which is a kind of EPLD. Our fault-locating and fault-repairing architecture uses universal test sets, fault-detecting logic, and self-repairing circuits with spare devices. The design method allows to detect, diagnose, and repair all multiple stuck-at faults which might occur on E/sup 2/CMOS cells in programmable AND plane. 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 the self-repairable GAL will last longer in the field.