Patent ID: 8866555

Claim:
A power amplifier circuit, comprising: an amplifier receiving an input signal to be amplified and one or more control signals from a controller; a power input coupling the amplifier to a power supply; a transformer providing the amplified signal from the amplifier to a load, comprising a primary inductor and a secondary inductor; wherein: a first capacitor is coupled in parallel with the primary inductor; and a second capacitor is coupled in parallel with the secondary inductor; wherein at least one of the first and second capacitors has a variable capacitance; wherein the controller: measures a change in power from the power supply under constant load, and in response to the measured change in power, retrieves one or more control signals from a lookup table and transmits the one or more control signals to change the capacitance value of the first capacitor and the capacitance value of the second capacitor sufficient to maintain the efficiency of the amplifier under the measured change in power, measures a change in load under constant power, and in response to the measured change in load, retrieves one or more control signals from a lookup table and transmits the one or more control signals to change the capacitance value of the first capacitor and the capacitance value of the second capacitor sufficient to maintain the efficiency of the amplifier under the measured change in load.