| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier which has the amplification efficiency improved to be able to be used in a wide frequency band in consideration of the issue that a conventional Doherty amplifier fails in optimum matching not to have amplification efficiency improved and doesn't allow the frequency band to be widened. SOLUTION: The amplifier includes a first amplification circuit operating as a class AB amplifier, a second amplification circuit operating as a class B or C amplifier, a composition point where an output of the first amplification circuit and that of the second amplification circuit are composited through an impedance converter comprising transmission line having electric lengths other thanλ/4. The impedance converter has a plurality of transmission lines different by electric length and is capable of switching connection to one of transmission lines in accordance with a frequency of an input signal. COPYRIGHT: (C)2007,JPO&INPIT
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