A technique for deriving a linear model for pulse width modulated converters is presented, which is similar to a Thevenin equivalent circuit. The linear models for the boost, buck, and boost-buck power stages are derived. The technique is applicable to other configurations and variations of pwm converters as well. The pulse width modulated power stage switch and diode may, in general, be replaced by a transformer and a dependent current source. As a result, the model can be very efficiently programmed on ECAP or any other linear circuit analysis computer program.