RF power amplifier having improved power supply for RF drive circuits

Abstract

A RF power amplifier system is presented herein including a RF source for providing a train of RF pulses exhibiting RF cycles of a fixed frequency and wherein each pulse is of a fixed amplitude and duration. A bridge circuit is provided and it includes a first transistor switch for, when on, connecting the DC voltage source across a load for DC current flow therethrough in a first direction and a second transistor switch for, when on, connecting the DC voltage source across the load for DC current flow therethrough in a second direction. A switch driver serves, when enabled, to pass the RF pulses for driving the first and second transistor switches on and off at a frequency dependent upon that of the RF pulses and in such a manner that current from the DC voltage source alternately flows in the first and second directions through the load. A driver controller provides turn-on signals and selectively applies them to the switch driver for enabling the switch driver for passing the RF pulses to the transistor switches. A driver amplifier is interposed between the switch driver and each transistor switch in the bridge circuit. A DC to DC power supply supplies DC drive voltage to each driver amplifier wherein the power supply includes a second DC voltage source, a transformer having a primary winding and a plurality of secondary windings. A first switching transistor serves, when on, to connect the primary winding across the second DC voltage source. A control circuit turns the first switching transistor on and off in synchronism with the frequency of the RF pulses so that any DC supply ripple voltage at the secondary windings has a ripple frequency equal to the frequency of the RF pulses.

Dependencies are inferred from the claim text.