A C∞-continuous depletion capacitance model

The p-n junction depletion capacitance models of the SPICE and ADVICE circuit simulators are regional models that have discontinuities in high-order derivatives. This limits the order of integration that can be used for transient analyses, and can limit both the size of time steps that can be used during transient analyses and the accuracy of distortion analyses. In addition, the SPICE and ADVICE depletion capacitance models unphysically predict that the depletion charge increases without bound as applied forward bias increases. An improved depletion capacitance model that overcomes these problems is presented. The model is charge-based, single-piece, and C_∞-continuous, and has a finite maximum junction depletion charge under forward bias