Radio frequency power amplifier and method using a plurality of feedback systems

A radio frequency power amplifier arranged and configured to drive a resonant load comprising:

• a radio frequency switching stage with an output that is coupled to a resonant circuit and configured to provide an output signal with amplitude modulation corresponding to amplitude modulation of an input signal when powered from a fixed voltage power supply;
• a feedback control system coupled to the input signal and the output signal, the feedback control system comprising a sequencer configured to provide a sequencer output that is used to drive the radio frequency switching stage;
• and
• a second feedback system responsive to the sequencer output and configured to provide a second feedback signal that is coupled to the feedback control system, where the sequencer output has an OFF state that begins at a variable time corresponding to the input signal, the output signal, and the second feedback signal.

A radio frequency power amplifier arranged and configured to drive a resonant load comprising:

• a radio frequency switching stage with an output that is coupled to a resonant circuit and configured to provide an output signal with amplitude modulation corresponding to amplitude modulation of an input signal when powered from a fixed voltage power supply;
• a feedback control system coupled to the input signal and the output signal, the feedback control system comprising a loop filter providing a filter signal that is coupled to an input of a sequencer, the sequencer configured to provide a sequencer output that is used to drive the radio frequency switching stage;
• and
• a biasing system configured to couple an offset signal to the input of the sequencer, the sequencer output changing states in accordance with the offset signal and the filter signal.

A method of providing a radio frequency signal with complex modulation comprising:

• filtering a combination of an input signal and a first feedback signal to provide a filtered signal, the input signal including complex modulation;
• generating, responsive to the filtered signal, a quantized signal having an OFF state that begins at a variable time;
• providing, responsive to the quantized signal, a second feedback signal that is deployed to affect the generating the quantized signal;
• and
• controlling a radio frequency switching stage with the quantized signal to provide an output signal to a resonant load, the output signal comprising an amplified version of the input signal with the complex modulation, the first feedback signal corresponding to the output signal.