Failure Analysis and Improvement of Bandgap Start-up Circuit by FIB

Based on a failure analysis case of abnormal operating current of an ADC (Analog to Digital Convertor) chip, a step-by-step fault location method is introduced in this paper. The fault is located using this method, and FIB (focused ion beam) technology is involved to verify the accuracy of fault location. Meanwhile, another simulations verification method is adopted, which reveals that the failure reason lies in the reduction of the core capacitance in bandgap start-up circuit caused by inconsistencies of the process. At last, some suggestions are proposed to help fast location in the similar failure and to ensure that this risk can be effectively avoid in the future relevant design.