| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-frequency power amplifier having a simple configuration, which reduces the level of a signal to be fed-back through a bias circuit and improves the stability in an amplifier in each stage. SOLUTION: The high-frequency power amplifier is provided with multiple stages of amplifiers 11, 12 and 13 which are continuously arranged in ascending order of the saturation power, a power efficiency control part 17 which selectively introduces the outputs of the amplifiers of the respective stages via switching circuits 14 and 15 to an output terminal, according to output power demanded and also which cuts-off amplifiers in the post-stage of the amplifier, which an output is taken from, and an output delay line 16 which is connected to a part between the last stage amplifier and the output terminal and which has a line length to obtain a high impedance, as seen from the side of the output terminal, when the last stage amplifier is cut-off.
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