TOTAL-DOSE EFFECTS ON NEGATIVE VOLTAGE REGULATOR

Functional failure at low dose level (4 Krad(Si)) on voltage regulator s (LM137) from different manufacturers are analysed. Dose rate effects on parts hardness are evaluated, showing that lowering the dose rate degrade more the IC's in the range 55 rad(Si)/s- 0,8 rad(Si)/s A failu re mechanism is proposed, mainly based on circuit analysis, voltage co ntrast measurements, local irradiation and local electrical measuremen ts with probe station. A spice simulation was performed, providing qua ntitative informations on the degradation. In the light of such a fail ure analysis and dose rate effects, practical implications on radiatio n assurance are discussed.