Design and Performance of Two 1k CMOS/SOS Hardened RAMs

RCA is under contract to DoD to develop two 5V 1K CMOS/SOS RAMs capable of meeting stringent total dose and transient radiation levels. This paper presents the design, operation, characterization, and test results of the RAMs´ capabilities to meet these radiation levels. The radiation resistance of these circuits is enhanced through design by dominant PMOS utilization, the exclusion of source followers, and tolerance to large threshold voltage shifts. Test results on further enhancement through radiation hardened processing are presented. This effort demonstrates a factor of 5 to 10 improvement in circuit radiation hardness by consideration of technology radiation characteristics in the design phase. Hardened processing can extend the performance of these parts to total dose environments in excess of 500K rads making them useful in extended space missions and severe military environments.