| 摘要 |
A filter includes a capacitor (1) connected between the input end IN and the output end OUT of signals and constant current circuits (2, 3) of MOS structure connected between the power source VDD and the ground, and by connecting the output side node of the capacitor (1) and the intermediate node of the constant current circuits (2, 3). Thus, the cut-off frequency of the filter is reduced by adjusting the value of a current passed through the constant current circuits (2, 3), instead of increasing the circuit area required by using a capacitor having a large capacitance value or a resistor having a large resistance value.
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