Single Event Error Immune CMOS RAM

A technique involving resistive decoupling has been developed and applied to the memory cells of a 1024-bit CMOS static RAM to provide immunity to single event upset by cosmic rays. Doped polysilicon resistors were inserted in the inverter-pair cross-coupling lines of an existing memory-cell design with negligible effect on the device operating characteristics. Computer simulations, as well as laboratory tests with energetic krypton ions, imply the effectiveness of this approach to solving the single event upset problem in satellites. This technique is expected to be applicable to other devices of this type, including those with higher levels of integration.