AbstractAn approach to the simulation of pulse width modulation (PWM) direct current–direct current (DC‐DC) converters operated under continuous current mode (CCM) and discontinuous current mode (DCM) is presented. It is based on the use of the Laplace transform and of dedicated models for controlled switches and diodes. Time‐domain waveforms are obtained from network functions representing the circuit under analysis without assuming small‐signal approximation. A program implementing the proposed approach has been also developed by exploiting symbolic analysis techniques. Because of its symbolic nature, it can profitably support numerical simulators in design optimization phase. Its characteristics and potentialities are shown through examples and experimental tests.