Modelling the BiCMOS switching delay including radiation effects

The effect of ionising radiation on the BiCMOS switching response has been studied. The radiation-induced surface recombination current in the base of the bipolar transistor and the radiation-induced resistive leakage paths in the BiCMOS structure have been modelled as functions of the interface state density and the oxide trapped charge density. Radiation effects on the MOSFET and the bipolar transistor including leakage paths in the BiCMOS structure have been incorporated into the equivalent circuit of the proposed model. A semianalytical solution of the transient response of the BiCMOS gate is obtained including high injection and high current base push-out effects. The proposed model is compared with experimental data and with MEDICI simulations, and the agreement is good over a wide range of radiation levels. The BiNMOS gate has been demonstrated to be more radiation hard as compared to the BiPMOS gate