| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic gain controller capable of performing stable gain control without depending upon the phase of a detection signal when the detection signal is saturated. SOLUTION: This automatic gain controller is provided with a variable gain amplifier capable of controlling gain by a gain control signal, an orthogonally detecting means for orthogonally detecting a signal amplified by the variable gain amplifier and outputting a detected common-mode signal and a detected orthogonal signal, a detection level calculating means for receiving the detected common-mode signal and the detected orthogonal signal and outputting a detection level signal, a limiter means for saturating the detection level signal to the upper limit to obtain a limiter output when the detection level signal is equal to and greater than the upper limit, and a gain control signal generating means for generating a gain control signal on the basis of the limiter output. According to the automatic gain controller, stable gain control can be performed without depending upon the phase of the detection signal by saturating the detection level signal to the upper limit when the detection level signal calculated from the detected common-mode signal and the detected orthogonal signal exceeds a predetermined upper limit. COPYRIGHT: (C)2006,JPO&NCIPI
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