US Patent 7917106 RF power amplifier controller circuit including calibrated phase control loop

An RF power amplifier system comprises an amplitude control loop and a phase control loop. The amplitude control loop adjusts the supply voltage to the power amplifier based upon the amplitude correction signal indicating the amplitude difference between the amplitude of the input signal and an attenuated amplitude of the output signal. The phase control loop adjusts the phase of the input signal based upon a phase error signal indicating a phase difference between phases of the input signal and the output signal. The phase control loop may comprise one or more variable phase delays introducing a relative phase delay to allow the phase differences between the input and output signals of the PA circuit to be within a range compatible with a phase comparator generating the phase error signal, and a low frequency blocking module that removes the larger extent, lower frequency components of the phase error signal.