Transient analysis of diode switching circuits including charge storage effect

Abstract

An efficient method for the transient simulation of diode switching circuits using the diode characteristic model, which takes into account the diode charge storage effect, is presented. The diode characteristic model is derived for a step-junction diode under the assumption of low-level injection. Unlike Linvill's multisection (physical) model that requires many lumped circuit elements for the analog transmission-line modeling of carrier diffusion and recombination processes, the diode characteristic model simulates such carrier redistribution phenomenon by using very few circuit elements and achieves the same simulation accuracy with two order reduction of computer simulation time. The diode characteristic model is derived from transforming the carrier continuity equation into an RCG transmission-line equation and is synthesized with lumped circuit elements derived from the Pade and Ritz optimization methods. For further reduction of computer simulation cost, the diode characteristic model is reduced into a time-varying characteristic model consisting of a depletion capacitor connected in parallel with a current source generated by recursive convolution integration. The current source has both forward and reverse current components for an accurate simulation of the storage charge recovery phenomenon. The diode recovery phenomenon and the transient response of a diode-terminated interconnect are simulated for illustrations. The simulation accuracy has been verified by using a mixed-level circuit and device simulator.