SPICE modeling of power PiN diode using asymptotic waveform evaluation

A new power diode model is developed and implemented as a PSPICE subcircuit. The starting point of the new model is a continued-fraction expression in the Laplace domain of the carrier distribution in the base region. By truncating the continued-fraction expansion, lumped RC representations of the base region are easily obtained. In the time domain, this approach approximates of the exact behavior of the carrier distribution with a sum of decaying exponentials, obtained by matching the moments of the exact carrier distribution. The proposed model takes into account emitter recombination in the highly doped end regions, conductivity modulation in the base and the moving-boundaries effect during reverse-recovery, showing good convergence properties and fast simulation times. Comparisons between the results of the SPICE models and numerical device simulations are presented.