| 摘要 |
An envelope level of an output of a variable gain power amplifier 1 is detected by a detector 5. An envelope level of an output of the variable gain power amplifier 1 detected by the detector 5 and a waveform of a reference signal which is generated from a reference signal generator 7 are compared. A gain of the variable gain power amplifier 1 is controlled in accordance with a comparison output. Upon leading of a transmission output, the reference signal is raised from a ground level to a rest value higher than the rest value of the detector 5. After the reference signal entered a response raised along a cosine square wave. Upon trailing of the transmission output, the reference signal is smoothly reduced to a value near the rest value of the detector 5 along a cosine square wave and is maintained at a value near the rest value of the detector 5. After the negative feedback loop did not respond, the reference signal is reduced to the rest value of the detector 5 or less. <IMAGE>
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