An object of the invention is to provide a polar modulation transmitter that can perform adaptive distortion compensation processing without the need for a synchronization adjustment circuit for synchronizing an input baseband signal and an output signal of a power amplifier. An adaptive operation control section 1501 measures the unbalance amount of an output spectrum of a power amplifier 1 and a coefficient adjustment determination section of the adaptive operation control section 1501 performs iteration control so that if the unbalance amount is equal to or greater than a predetermined threshold value, coefficient information output to a distortion compensation processing circuit 1301 is adjusted and an adjustment is made to distortion compensation processing in the distortion compensation processing circuit 1301 and if the unbalance amount is less than the predetermined threshold value, the coefficient information is maintained, whereby the characteristic change of the power amplifier 1 at the environmental temperature change time can be adaptively compensated for without using a synchronization adjustment circuit for synchronizing an input baseband signal and an output signal from the power amplifier 1. 展开▼
