US Patent 7200031 Proton and heavy ion SEU resistant SRAM

A method and system is disclosed for reducing proton and heavy ion SEU sensitivity of a static random access memory (SRAM) cell. A first passive delay element has been inserted in series with an active delay element in a first feedback path of the SRAM cell, and a second passive delay element has been inserted in a second feedback path of the SRAM cell. The passive delay elements reduce the proton SEU sensitivity of the SRAM cell, and the active delay element reduces the heavy ion sensitivity of the SRAM cell. The passive delay elements also protect the SRAM cell against SEUs that may occur when the SRAM cell is in dynamic mode.