Patent ID: 8340604

Claim:
A radio frequency (RF) power amplifier system, comprising: a power amplifier coupled to receive and amplify an RF input signal to generate an RF output signal; and a power amplifier controller including: an amplitude control loop comprising: an amplitude comparator comparing an amplitude of the RF input signal with an attenuated amplitude of the RF output signal to generate an amplitude correction signal indicative of an amplitude difference between the amplitude of the RF input signal and the attenuated amplitude of the RF output signal; and a power supply coupled to receive the amplitude correction signal and generating an adjusted supply voltage provided to the power amplifier based upon the amplitude correction signal; and a phase control loop comprising: a phase comparator comparing the phase of the RF input signal with the phase of the RF output signal to generate a phase error signal indicative of a phase difference between phases of the RF input signal and the RF output signal; a variable phase delay coupled between the RF output signal and the phase comparator introducing a phase delay in the phase control loop to adjust the phase difference between the phases of the RF input signal and the RF output signal to be within an operating phase range of the phase comparator; a phase shifter coupled to the power amplifier, the phase shifter shifting the phase of the RF input signal to the power amplifier based upon the phase error signal to reduce phase distortion generated by the power amplifier; and a low frequency blocking module coupled between the phase comparator and the phase shifter, the low frequency blocking module allowing frequency components of the phase error signal higher than a predetermined frequency to be passed from the phase comparator to the phase shifter.