| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency conversion circuit composed of a CMOS process proper to a low-voltage operation, and to provide a radio communication device thereof. SOLUTION: A rail-to-rail type differential amplifier is used at the switching operation stage of the frequency conversion circuit, and the differential amplifier has a common-mode voltage detecting means detecting the common-mode voltage of a differential signal in an output and a common-mode voltage applying means applying the common-mode voltage to an input. A negative-feedback loop means for converging the common-mode voltage detected by the common-mode voltage detecting means to a specified reference voltage is disposed between the common-mode voltage detecting means and the common-mode voltage applying means, and the instability of the common-mode voltage is improved by the feedback of a common mode. COPYRIGHT: (C)2008,JPO&INPIT
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