A new semiconductor junction diode space charge layer capacitance model

A new expression for the semiconductor junction diode space-charge capacitance has been derived. This new equation preserves the traditional meaning of zero-voltage capacitance and built-in potential and, without introducing any new fitting parameters of its own, eliminates the fitting parameter FC currently used in SPICE. In a single expression, the new model provides an accurate model for the junction capacitance for all reverse bias voltages and for forward bias up to the built-in voltage. Both the capacitance expression and its derivatives are continuous finite values of the diode capacitance for all junction voltages. A charge expression for this new model is also presented, and it is shown that with this expression charge conservation is preserved in circuit simulators