PURPOSE: To optimize intermodulation distortion generated at a high output amplifier to all transmission frequencies by connecting a delay equalizer and an amplitude equalizer to a path of the 1st high frequency signal with respect to high frequency band pre-distortion type linearizer and matching the phase of distortion generated in the linearizer by a delay equalizer with the phase of distortion generated in power amplifier.

CONSTITUTION: A high frequency signal applied to a high frequency signal input terminal 1 is led to a linearizer 2 and branched into two, 1st and 2nd high frequency signals by a hybrid 3. The 1st high frequency signal is inputted to a delay equalizer 9 through a distortion generator 5 and the delay equalizer 9 matches the phase of distortion generated by the linearizer 2 with the phase of distortion generated in the high output amplifier 7. Then the output of the delay equalizer 9 is inputted to an amplitude equalizer 10, which matches the amplitude of the distortion generated by the linearizer 2 with the amplitude of the distortion generated in the high output amplifier 7. Thus, the phase and amplitude of the distortion generated in the linearizer 2 are matched with the phase and amplitude of the distortion generated in the high output amplifier 7 in all transmission frequencies.