| 摘要 |
PROBLEM TO BE SOLVED: To provide a power amplifier whose power consumption can be reduced while keeping the performance of an amplifier element is maintained even when a matching condition of an amplifier means is fluctuated. SOLUTION: The power amplifier is provided with a gain variable means 3 that adjusts the gain for a high frequency input signal, an amplifier means 4a that amplifies the signal whose gain is adjusted, a plurality of output matching means 8a, 8b that are placed in parallel, match outputs of the amplifier means 4a and provide an output, changeover means 6a, 6b that select either of a plurality of the output matching means and connects the selected output matching means to the amplifier means 4a, and a control means 5a that provides an output of a signal to control the gain of the gain variable means, a signal to control an operating current of the amplifier means and a signal to control the switching of the changeover means. Even when the matching condition of the amplifier means is fluctuated, selecting an output matching means suitable for an operating current of the amplifier means can keep an optimum load to reduce the power consumption.
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