| 摘要 |
PROBLEM TO BE SOLVED: To provide a Doherty amplifier preventing the lowering of the gain of the Doherty amplifier and being capable of improving an efficiency regarding the Doherty amplifier. SOLUTION: The Doherty amplifier has a signal branch circuit 21 branching an input signal in the two directions, a carrier amplifier 1 receiving one output from the signal branch circuit 21, a firstλ/4 line 2 receiving an output from the carrier amplifier 1 and a comparison circuit 22 comparing the other output from the signal branch circuit 21 and the threshold voltage of the peak amplifier 4. The Doherty amplifier further has a high-frequency switch 23 determining whether or not the peak amplifier 4 is incorporated into the circuit in response to the output from the comparison circuit 22, a secondλ/4 line receiving the output from the high-frequency switch 23, the peak amplifier 4 receiving the output from theλ/4 line and a load 5 receiving a signal synthesizing the output from the firstλ/4 line 2 and the output from the peak amplifier 4. COPYRIGHT: (C)2009,JPO&INPIT
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