A power transfer system for transferring power from a first circuit to a second circuit by a differential signal generated in the first circuit includes a first isolation element for transmitting a first component of the differential signal between the first and second circuits. The system also includes a second isolation element for transmitting a second component of the differential signal between the first and second circuits. A digital rectifier is coupled to the first and second isolation elements for generating a rectified voltage in response to the first and second components of the differential signal. The system includes circuitry for monitoring the rectified voltage and generating a signal representative of the rectified voltage. The system also includes a controller for changing the rectified voltage in response to the signal representative of the rectified voltage.