| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem wherein offset voltage potential is tended to change for of an output signal of a switched capacitor filter (SCF) circuit, which constitutes an inverting amplifier circuit by an inverter. SOLUTION: The SCF circuit 2 includes two SCFs 4 and 6 equipped with inverter circuits 14a and 14b at the output stage, and generates a differential type output signal. Resistors R<SB>A</SB>and R<SB>B</SB>, connected between differential output terminals, divides the voltage of differential signal to generate middle point potential voltage V<SB>CM</SB>. A comparator 30 compares the V<SB>CM</SB>with target potential voltage V<SB>CT</SB>. A transistor connected between a CMOS inverter of the inverter circuits 14a and 14b and ground potential changes channel resistance according to the comparison results at the comparator 30, changes bias potential voltage of the output end of the CMOS inverter, and carries out feedback control for feeding the offset potential voltage towards the V<SB>CT</SB>. COPYRIGHT: (C)2011,JPO&INPIT
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