| 摘要 |
PROBLEM TO BE SOLVED: To provide an active filter circuit that has a boost function of signal amplitude in the vicinity of a cut-off frequency without deteriorating the group delay characteristic and to provide a semiconductor integrated circuit incorporating the filter circuit. SOLUTION: The active filter circuit is provided with a 1st filter (101) that passes an input signal in a desired frequency band, a 2nd filter (102) that is connected to the 1st filter, a differentiation circuit that differentiates the input signal, and a current output amplifier (113) that outputs a current corresponding to the change in the input signal on the basis of an output from the differentiation circuit, and the output current from the amplifier (113) is added to an output of the 2nd filter (102).
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