Self-repairable GALs

This paper describes the concept of self-testable and self-repairable Gener ic Array Logic (GAL) devices for high security and safety applications. A d esign methodology is proposed for self-repairing of a GAL which is a kind o f Electrically Programmable Logic Devices (EPLDs). The fault-locating and f ault-repairing architecture with electrically re-configurable GALs is prese nted. It uses universal test sets, fault-detecting logic, and self-repairin g circuits with spare devices. The design method allows to detect, diagnose , and repair of all multiple stuck-at faults which might occur on (ECMOS)-C -2 cells in programmable AND plane. A self-repairing methodology is present ed, based on our design architecture. A "column replacement" method with ex tra columns is introduced that discards each faulty column entirely and rep laces it with an extra column. The evaluation methodology proves that a sel f-repairable GAL will last longer in the field. It gives also information o n 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, a n ideal point could be estimated, where the maximum reliability can be reac hed with the minimum cost. (C) 2001 Elsevier Science B.V. All rights reserv ed.