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An analysis of charge pump design for improved radiation tolerance of phase locked loops is presented. Two radiation-hardened-by-design approaches are considered to mitigate the total ionizing dose damage of the circuit, and a thick-film SOI SiGe process technology has been used to reduce charge collection of single event strikes. The results show that a modified design approach to implement the charge pump using SiGe HBTs can provide advantages in radiation tolerance to improve tri-state leakage performance, particularly for missions expecting large accumulated doses. [ABSTRACT FROM PUBLISHER]

We present results on the effects of ELDRS at dose rates of 10, 5, 1, and 0.5 mrad(Si)/s for a variety of commercial, radiation hardened, and ELDRS-free devices. We observed low dose rate enhancement below 10 mrad(Si)/s in several different part types. The magnitudes of the low dose rate enhancement varied substantially. The most notable case showed dose rate sensitivity in the functional failures for a commercial voltage regulator, with initial failures occurring after 10 krad(Si) for the parts irradiated at 0.5 mrad(Si)/s. Radiation hardened and ELDRS-free devices also showed ELDRS at the ultra-low dose rates. An ELDRS-free high power regulator showed a low dose rate enhancement factor of \times33 after 10 krad(Si) for parts irradiated at 0.5 mrad(Si)/s. The enhanced degradation at the ultra-low dose rates present challenges for hardness assurance. [ABSTRACT FROM PUBLISHER]

Many bipolar linear integrated circuits have been shown to exhibit enhanced low dose rate sensitivity (ELDRS), where a product may have worse total ionizing dose (TID) performance when exposed to ionizing radiation at a low dose rate (LDR) than when exposed at a high dose rate (HDR). Recent studies on test cells have suggested that submicron CMOS processes may also exhibit ELDRS. Some CMOS products, although not considered to be BiCMOS, do contain active bipolar elements using the parasitic bipolar structures present in all bulk CMOS processes. Three mixed-signal CMOS products, one digital-to-analog converter (DAC) and two analog-to-digital converters (ADC), using different submicron CMOS processes and using active parasitic bipolar structures were put through LDR TID testing to determine if actual products exhibit ELDRS. MIL-STD-883 TM1019 contains a test method to qualify products that fail HDR TID testing for LDR environments by using HDR testing along with a room temperature anneal. This test method was previously demonstrated on supermicron process nodes. It has been suggested that this test method is not valid for submicron processes. The test method was validated on a submicron CMOS product using the LDR test data from one of the products in this study. [ABSTRACT FROM AUTHOR]

An accelerated total ionizing dose (TID) hardness assurance test for enhanced low dose rate sensitive (ELDRS) bipolar linear circuits, using high dose rate tests on parts that have been exposed to molecular hydrogen, has been proposed and demonstrated on several ELDRS part types. In this study several radiation-hardened “ELDRS-free” part types have been tested using this same approach to see if the test is overly conservative. [ABSTRACT FROM AUTHOR]