Prevention of Radiation Induced Latchup in Commercially Available CMOS Devices

Commercially available bulk CMOS devices have been found susceptible to transient radiation induced latchup particularly when there is little or no current limiting in the power supply. A resistor in the power supply line of sufficient size to prevent latchup may cause excessive voltage drop when the device is operating dynamically. A series inductor in the power supply line does not have this drawback. An inductor-resistor-capacitor (LRC) network was developed to prevent latchup in HM-6551, 256×4 bit bulk CMOS random access memories (RAMs). The LRC network was successfully tested with single and multiple RAMs using a Febetron 705 in the x-ray mode at 1×1010 rad(Si)/s. The parametric values of the LRC network should be experimentally determined at the highest gamma dose rate required for system survivability. The technique should be cost effective even with this restriction.