QPSK power amplifier distortion correction system

摘要

A quadrature phase-shift keying modulator produces a QPSK signal which is amplified by a power amplifier. The amplitude gain of the power amplifier is controlled in response to an amplitude difference between the QPSK signal output by the modulator and the amplified QPSK signal output by the power amplifier. A phase detector, connected in series between the modulator and the power amplifier, eliminates amplitude variations from the QPSK signal prior to amplification. A voltage-controlled phase shifter, connected in series between the phase detector and the power amplifier, shifts the QPSK signal in phase by an amount responsive to amplitude information in the QPSK signal.