A Radiation-hardened Over-temperature Protection Circuit Using a Dynamic Comparison Technique

The total-ionizing-dose (TID) effect has different influences on bipolar junction transistors, resistors, and MOSFETs, which leads to significant drifts in the over-temperature threshold in the traditional over-temperature protection circuit (OTPC). An OTPC with a dynamic comparison technique is proposed to improve the radiation-hardened capability. The proposed radiation-hardened OTPC employs two identical sensors to monitor the temperature and convert it into voltage for comparison to determine if over-temperature occurs. The voltage drifts caused by TID effects on two sensors vary dynamically and offset each other, so the over-temperature threshold will not drift theoretically. The normalization method is used to process measurement results to get a visual comparison. The measurement results show that the threshold drift of the proposed OTPC is 5.0% lower than that of traditional OTPC at 30 krad(Si), 7.1% lower at 50 krad(Si), and 10.3% lower at 100 krad(Si). Therefore, the proposed OTPC reduces the threshold voltage drifts effectively and has a good radiation-hardened effect.