| 摘要 |
A dual band power amplifier circuit comprising first and second power amplifiers each operative to amplify an RF signal of a particular frequency range at an output terminal thereof, wherein the output terminals of the amplifiers are coupled at a common node, and wherein the amplifiers are operative in a first saturation mode and a second linear mode; a control circuit for providing a first control signal to the first power amplifier and a second control signal to the second power amplifier for controlling the mode of operation of each amplifier; and a switching device having a first terminal coupled to the outputs of the first and second power amplifiers at the common node and to a power source at a second terminal, the switching device responsive to a third control signal from the control circuit for providing a high output impedance to the amplifiers for limiting leakage current when the first and second amplifiers are in the saturation mode, and for enabling current to be drawn from the power source to a particular one of the power amplifiers when the particular power amplifier is in the linear mode.
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