Patent ID: 8106713

Claim:
A power amplifier circuit comprising: a transistor for receiving a signal to be amplified at an input and for outputting an amplified signal at an output; an envelope modulated power supply connected to the transistor output for providing a modulated power supply to the transistor; a resonant network including a capacitance of the transistor and an inductance of a supply feed of the modulated power supply which resonant network presents a supply impedance to the transistor, wherein at certain frequencies across a range of operational frequencies the supply impedance presented to the transistor by the resonant network increases; a resistive element connected at the transistor output, such that the supply impedance presented to the transistor is the combined impedance of the first resonant network and the resistive element, such that the supply impedance presented to the transistor is stable across a range of operational frequencies; and a reactive element connected in series with said resistive element, wherein said reactive element comprises a capacitive element or an inductive element in series with a capacitive element.