| 摘要 |
PROBLEM TO BE SOLVED: To improve power efficiency when a gain of a Doherty amplifier is increased. SOLUTION: In the Doherty amplifier including an amplifying circuit 4 operating in class-AB, an amplifying circuit 5 operating in class-B or class-C and a circuit having a summing node 62 for combining outputs of the amplifying circuit 5 and the amplifying circuit 4 through a transmission line 61, class-AB and class-C preamplifiers 91 and 92 are provided on a pre-stage of the amplifying circuit 4 and the amplifying circuit 5, so that efficiency of the entire amplifier is improved. Thus, an absolute level of a loss relating to distribution is decreased rather than connecting a common amplifier before the Doherty amplifier, so that high efficiency and low distortion can be accomplished. COPYRIGHT: (C)2006,JPO&NCIPI
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