Dose rate effects of a bipolar A/D converter

Total ionizing dose-rate tests of an AD574 analog-to-digital converter were performed at dose rates of 2 to 10 rad(Si)/sec at an operating temperature (41/spl deg/C). The AD574 has been manufactured by Analog Devices using Bipolar II technology. Results were compared with previous results from others to see trends. The results show increasing failure rate as dose rate increases. Unlike off-line test results at room temperature, no sign of degradation at low dose rates was found from the in-situ tests of AD574 devices at elevated temperature. Fast recovery of failure within 20 minutes post-irradiation annealing was observed. This recovery automatically rules out an interface-trap buildup as a dominant failure mechanism. The contribution of bulk-oxide charges seems to be a major factor.