| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier which can effectively suppress AM-PM distortion and is compact and low-cost. SOLUTION: A Doherty amplifier is provided with: a distortion pre-compensating circuit 7 in the preceding stage of an input distributing circuit 2; and a distortion pre-compensating circuit 9 in the preceding stage of a peak amplifier 4 respectively. An input signal from an input terminal 1 is distributed by the input distributing circuit 2 to a carrier amplifier 3 and a peak amplifier 4, and amplified only by the carrier amplifier 3 until the carrier amplifier 3 gets saturated, but when the carrier amplifier 3 gets saturated, the peak portion of the input signal above the level at which the carrier amplifier 3 gets saturated is amplified. However, the AM-PM distortion caused by the carrier amplifier 3 is compensated by the distortion pre-compensating circuit 7 and the AM-PM distortion caused by the peak amplifier 4 is compensated by the distortion pre-compensating circuit 7 and distortion pre-compensating circuit 9. COPYRIGHT: (C)2007,JPO&INPIT
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