Patent ID: 7848452

Claim:
A distortion compensating apparatus comprising: a distortion compensator for compensating for distortion caused by a power amplifier according to distortion compensation coefficients that are stored in a distortion compensation coefficient memory in connection with a transmission signal and that correspond to amplitude of the transmission signal; a quadrature modulator for carrying out quadrature modulation of a distortion compensated signal; a power amplifier for power amplifying a quadrature modulated signal; a quadrature demodulator for carrying out quadrature demodulation of a power amplified signal and for outputting a feedback signal; a distortion compensation coefficient arithmetic circuit for calculating, from the transmission signal and the feedback signal, distortion compensation coefficients corresponding to the amplitude of the transmission signal, and for updating distortion compensation coefficients stored in the distortion compensation coefficient memory; an IQ imbalance compensation coefficient arithmetic circuit for calculating, from correlation values of the transmission signal and the feedback signal, IQ imbalance compensation coefficients in real time for compensating for IQ imbalance in said quadrature modulator; and an IQ imbalance compensator for compensating for the IQ imbalance with respect to the distortion compensated signal output from said distortion compensator according to the IQ imbalance compensation coefficients obtained in real time, and for outputting an IQ imbalance compensated signal to said quadrature modulator.