| 摘要 |
PROBLEM TO BE SOLVED: To provide a power amplifier whose distortion adjustment is easy in a plurality of frequency bands. SOLUTION: The power amplifier 1 includes: a first bipolar transistor Q1 of an emitter grounded type which amplifies high frequency signal inputs into a base, and outputs from a collector; an impedance circuit 2 which can conduct direct currents, and an end of which is connected to a base of the first bipolar transistor Q1; a second bipolar transistor Q2 whose emitter is connected to another end of the impedance circuit 2; a voltage supply terminal Nvb which supplies bias voltage to the base of the first bipolar transistor Q1 through the impedance circuit 2 from a collector of the second bipolar transistor Q2; a base voltage generation circuit 4 which generates base voltage of the second bipolar transistor Q2; and a filter circuit 3 which is arranged between the emitter of the second bipolar transistor Q2 and a grounded node, and is non-conductive for a direct current component, and changes its impedance according to a frequency for an alternative current component. COPYRIGHT: (C)2008,JPO&INPIT
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