| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve such a problem that it is difficult to simultaneously perform the suppression of carrier leakage and gain control while suppressing a circuit size in a conventional modulation circuit. <P>SOLUTION: A modulation circuit has: a modulator for modulating an inputted signal and outputting the modulated signal; a test signal generation circuit for outputting a test signal with equal amplitude in a positive direction and a negative direction from reference potential to the modulator; a detector for extracting an envelope of the signal output from the modulator; a decision circuit for deciding the amplitude of the envelope extracted by the detector; a first control circuit for adjusting an offset level of the modulator so that the amplitude of the envelope extracted by the detector is fixed on the basis of the decision results of the decision circuit; and a second control circuit for setting the amplitude value of the signal output from the modulator to a required amplitude value on the basis of the decision results of the decision circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT |
