DOHERTY AMPLIFIER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a Doherty amplifier circuit having less distortion by improving AM-PM characteristics (amplitude-phase characteristics) because a conventional Doherty amplifier circuit has a problem that variation in AM-PM characteristics is complicated and sufficient distortion compensation is difficult. SOLUTION: The Doherty amplifier circuit is configured so that a plurality of Doherty amplifiers having different AM-PM characteristics are connected in cascade, for example, a Doherty amplifier 20 employing a GaAsFET and a Doherty amplifier 30 employing an LD-MOSFET which have reverse AM-PM characteristics are connected in cascade. The Doherty amplifier circuit offsets phase shifts generated in each of the Doherty amplifiers to achieve excellent AM-PM characteristics as a whole, and reduce the distortion. COPYRIGHT: (C)2008,JPO&INPIT