In a transmission power amplifying unit used for radio communications, a non-linear
distortion compensator is provided before its main power amplifier. The compensator
compensates the main power amplifier for non-linear distortions so as to perform
non-linear distortion compensation prior to power amplification of a transmission
signal. The transmission signal that has undergone the non-linear distortion compensation
is amplified by the main power amplifier. The phase of either the output of the
amplifier or the transmission signal is controlled and these two signals are synthesized
so that they are in opposite phase. This operation can reduce non-linear distortion
components generated in the main power amplifier and thus power consumption of
the amplifier. As a result, power consumption of the auxiliary amplifier is reduced
and efficiency of power used in the linear compensated amplifying equipment can
be improved.
