A 256 Bit GaAs SRAM With Laser Programmable Spare Rows and Columns

A 256 bit GaAs SRAM has been designed that incorporates laser programming to allow any defective row or column to be replaced with a spare row or column. The spare circuits also have spare replace spare capability. The 256 bit SRAM is a precursor to larger memory designs. The repairability of defective cells, columns, rows, or decoders allows fully functional parts to be realized at the early stages of process development and eventually enhances production yield. This technique has been extensively used in the silicon industry. It is our belief that this is the first application to GaAs circuits.