Simulation-Based Study of Single Event Transients in a SiGe BiCMOS Low Power Operational Amplifier

Abstract

Energy depositions from highly ionized particles in space environments can induce transient current (voltage) pulses in microelectronic devices, called Single Event Effects (SEEs). This thesis uses simulations to investigate the single event response of a low power operational amplifier (Op Amp) designed in IBM 5AM (0.5 um) SiGe BiCMOS technology. Cadence Spectre, using single event current pulses similar to those produced using 3D TCAD simulations, were applied to simulate the Op Amp response for multiple circuit configurations. Key findings include long (>> 1ms) output perturbations for strikes to input bias devices, which induce currents well beyond the bias current used for the low power design. Unity gain configuration exhibited the longest perturbation among the simulated variants. Variation of single event pulse parameters exhibit relative insensitivity to temporal profiles for a given deposited charge, indicating that integrated charge drives the response given the relative fast (~ nanosecond) scale of the event compared to the slower output response time. Simulation results are used to estimate the effectiveness of radiation hardened by design (RHBD) variants of the heterojunction bipolar (HBT) devices used in the input stage in reducing the sensitive cross section. Results indicate that the guard rings may reduce the cross section for moderate to high LET values.