| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance efficiency in using power amplifier. Ž<P>SOLUTION: A power amplifier circuit device includes a driver amplifier, a switch, an amplifier path having a band pass filter and a power amplifier, and a bypass path which bypasses the power amplifier when excess gain and output power are not needed. When an RF-analog signal from the driver amplifier is switched to the amplifier path, the signal is band-pass filtered and amplified. Then the signal is split into an in-phase signal and a quadrature signal. Either the in-phase or quadrature signal is inverted and summed with the other in-phase or quadrature signal, and the summed signal is transmitted to an output port. When the RF-signal from the driver amplifier is switched to the bypass path, the power amplifier is turned off and the bypass path directs the signal to the output of the power amplifier, which appears as a high impedance to the signal. The signal is reflected from the power amplifier to the output port. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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