Ionizing-radiation-induced degradation in electronic power amplifiers

The effects of ionizing radiation on the performance of electronic power amplifiers with complementary power MOSFETs in the output stage are examined. It is shown that the primary effect of ionizing radiation on power MOSFETs is a shift in the threshold voltage. For p-channel power MOSFETs, this shift is always negative, and for n-channel devices, the polarity of the shift depends on part type, bias conditions, and dose rate. It was found that ionizing radiation leads to failure of the amplifier if the threshold voltage of the n-channel device increases with total dose. If both power MOSFETs exhibit a negative threshold-voltage shift, increases in power dissipation and output offset voltage result. The failure mode of the amplifier depends on the relative magnitude of the threshold-voltage shift in the p- and n-channel power MOSFETs, and on the polarity of the shift in the n-channel device.<>