| 摘要 |
A filter circuit includes two current amplifiers and two capacitors constituted of MOS or MIS transistors. An output terminal of the first current amplifier is connected to an input terminal of the second current amplifier, while an output terminal of the second current amplifier is connected to an input terminal of the first current amplifier. One end of the first capacitor is connected to the input terminal of the first current amplifier, while one end of the second capacitor is connected to the output terminal of the first current amplifier the other end thereof is grounded. When an input signal is supplied through the first capacitor, an output signal through a band-pass filter is issued from the output terminal of the first current amplifier, and an output signal through a high-pass filter is issued from the output terminal of the second current amplifier. An output signal through a trap filter or an all-pass filter is also issued by adding the input signal to the output signal of the first current amplifier.
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