Inclusion of nonlinear output capacitor behavior in zero-voltage switched circuit design

A methodology for including into the design of zero-voltage switching circuits the effects of nonlinear MOSFET output capacitance with respect to drain-source voltage is presented. The method relies on the relation between the charge and the voltage. Design equations for a zero-voltage switched, transition resonant half-bridge power converter are developed which include capacitor nonlinearity. Equations predicting switching losses for nonzero-voltage switching conditions are also derived. An experimental circuit operating at 10 MHz is used to compare the theoretical predictions to the experimental results.