| 摘要 |
PROBLEM TO BE SOLVED: To provide a gm-C filter capable of achieving broadband frequency characteristics without increasing parasitic capacitance in output of a transconductance amplifier. SOLUTION: In this invention, there are provided a slave filter 3 having the transconductance amplifier 1 and a capacitor circuit 2 and functioning as an original filter, and a self-regulation circuit 4A regulating variations in transconductance of the transconductance amplifier 12 and capacitance of the capacitor circuit 2, respectively. The self-regulation circuit 4A comprises the transconductance amplifiers 12, 13, a selection/arithmetic circuit 40, and a capacitor circuit 15 or the like. The selection/arithmetic circuit 40 selects one of output of the transconductance amplifiers 12, 13, or performs addition and subtraction between the output depending on the frequency characteristics required by the slave filter 3.
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