| 摘要 |
A high-frequency power amplifier system including a plurality of individual amplifiers connected in parallel, the amplifiers including switching-driven FET's. A fixed drain voltage is applied to one amplifier and a variable drain voltage is applied to another amplifier through a section including a DC-DC converter that converts the voltage according to a control value of a control signal. The turning on and off of the operation of the power amplifier is controlled by a control signal. Also, the circuit constants of a matching circuit are variable. In a high output power region, the power amplifier is turned on and, in a low output power region, turned off. Thereby, the decrease of efficiency of the power amplifier, owing to the DC-DC converter, may be suppressed to a minimum. The matching of the amplifier is adjusted when the power amplifier is switched on or off so as to improve efficiency. Consequently, it becomes possible to continuously control the output of the amplifier.
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