Abstract: A constant frequency power converter which includes a system to switch a resonant capacitive or inductive element during the power transfer cycle in a clamped series resonant converter. A feedback control system generates a pulse width modulated signal to switch the resonant element at the appropriate time. A conventional power MOSFET can be used as the switching device. The resonant control elements may be operated in series or parallel depending on the basic resonant topology selected. Applications include high frequency power converters where small size is of prime concern.