Radiation Hardened Registers

The requirement for radiation hardened registers has been identified for use with existing digital equipment to assure system survivability in nuclear radiation environments. The major problem has been that all semiconductor registers cannot be guaranteed to maintain their information after ionizing radiation transients above 5×109 rads (Si)/sec. Two approaches are shown for designing microelectronic register circuits for increased transient immunity based on the use of temporary storage media: a magnetic circuit and a capacitor circuit. The operation of the circuits are described as well as the features which impart hardness to them. They are compatible with +5V, IC families of saturated logic and are proposed for use with these circuits for specific function hardening. The results of transient tests show the magnetic circuit to work through 107 rads(Si)/sec to 8 × 1010 rads(Si)/sec. The capacitor circuit tests went up as high as 5 × 1010 rads (Si)/sec. Laboratory simulation on the capacitor circuit (using shunting transistors to approximate the effect of the circuit´s transistors storage times caused by radiation) indicates hardness to levels in excess of 5 x 1011 rads(Si)/sec.