Physically Based Predictive Model for Single Event Transients in CMOS Gates

An analytical model is presented to understand the time response of an inverter to ionizing particles based on physical equations. The model divides the output voltage transient response of an inverter into three time segments, where an ionizing particle striking through the drain-body junction of the OFF-state nMOS is represented as a photocurrent pulse. If this current source is large enough, the output voltage can drop to a negative voltage. In this model, the OFF-state nMOS is represented as the parallel combination of an ideal diode and the intrinsic capacitance of the drain-body junction, while a resistance represents an ON-state pMOS. The proposed model is verified by 3-D TCAD mixed-mode device simulations. In order to investigate the flexibility of the model, the effects of important parameters, such as ON-state pMOS resistance, doping concentration of P-region in the diode, and the photocurrent pulse are scrutinized.