Built-in self-diagnosis for repairable embedded RAMs

A method of built-in self-diagnosis (BISD) for repairable, embedded static RAMs (SRAMs) is presented. The BISD circuit, with self-repair, requires about 5% extra area in a 64-kb SRAM. The circuit contains a small reduced-instruction-set processor, which executes diagnosis algorithms stored in a ROM. These algorithms employ hybrid serial/parallel operations when external repair is available or modular operations when self-repair is required. The algorithms, hardware design, and design costs and tradeoffs are discussed