Patent ID: 7092269

Claim:
An H-bridge switching circuit for providing power to a load and connected to a supply reference voltage and a relative ground, comprising: four switches, a first through fourth switch, each comprising a drive input as well as a reference voltage connection and a power supply connection, the four switches being connected in an H-bridge configuration; an output connected to a secondary winding of a transformer that produces an output signal to the load, a first side of a primary winding of the transformer being connected to the first switch, and a second side of the primary winding of the transformer being connected to the fourth switch; four RF drives, a first through fourth RF drive, each respectively connected to the first through fourth switch drive inputs, the drives being configured such that the second drive is 180° out of phase of the first drive and includes a period of dead time during which both the first and second drives are off; and adjustment circuitry configured to adjust a phase of the third drive with respect to the first drive so that an overlap time when both the first drive and the third drive are turned on determines an amplitude of the output signal, the adjustment circuitry being further configured to adjust a phase of the fourth drive with respect to the second drive so that an overlap time when both the second drive and the fourth drive are turned on determines the amplitude of the output signal.