Ideal nonlinear distortion compensation is realized by removing an imperfection
of amplitude delay characteristic and an affection of inherent deviation that an
amplifier has. A linear distortion compensation factor calculating part (18)
estimates, based on quadrature demodulated signals (Ich, Qch),
the linear distortion characteristic occurring mainly due to imperfection of analog
circuits, such as a quadrature modulator (13) and a high-power amplifier
(14), and calculates and outputs a linear distortion compensation factor
for compensating the linear distortion. A linear distortion compensating part (12)
performs a pre-distortion (addition of a reverse characteristic of the linear distortion
characteristic) by multiplying the baseband signals (Ich, Qch) by the data of the
linear distortion compensation factor.