To effectively suppress a tertiary mutual modulation distortion even when an output power is changed.
Only a second higher harmonic wave component is extracted from the output wave of a main amplifier 100 by a second higher harmonic wave extraction filter 101, and that component is amplified so that a secondary mutual modulation component to be generated inside the main amplifier 100 by a second higher harmonic wave component fed back by an auxiliary amplifier 102 and a basic wave can become the same amplitude as a tertiary mutual modulation component of the basic wave to be generated inside the main amplifier 100. Afterwards, the phase of the second higher harmonic wave component outputted by the auxiliary amplifier 102 is shifted by a variable phase shifter 103 and a fixed phase shifter 104 so that the secondary mutual modulation component can become the relation of a phase inverse to that of the tertiary mutual modulation distortion component, and that component is fed back to the input side of the main amplifier. The fixed phase shifter 104 applies a fixed phase shift quantity when the level of passing power is a set fixed power. The variable phase shifter 103 changes a phase shift quantity corresponding to a change when the level of the passing power is changed from the set fixed power.
KAWADA MASAFUMI
MATSUBARA NAOKI
ADACHI YOSHIHIRO
