PURPOSE: To decrease the power consumption of a filter and to attain ease of large scale integration of the filter by realizing a high-order filter by means of three operational amplifiers regardless of a conventional method using operational amplifiers equivalent to the number of orders in the realization of the high-order filter.

CONSTITUTION: An input signal Vin at a terminal 1 is inputted to one input terminal 8-1 of the 1st switched capacitor filter 5 via an operational amplifier (OP- AMP) 2 and a part of the other signal Vin is inputted directly to the other input terminal 8-2 of the filter 5. An output from an output terminal 8-3 of the filter 5 is outputted from an output terminal 7-1 via an integration device 3, a part of the output of the integration device 3 comprising a capacitor Cf and an OP-AMP 3-1 is fed back to one input terminal 6-2 of the 2nd switched capacitor filter 6, a part of the output of the integration device 3 is fed back to the other input terminal 6-1 of the filter 6 via an OP-AMP4 and an output of the filter 6 is inputted to the integration filter 3. The number of OP-AMPs is not increased in this way even if the number of the order of the 1st and 2nd filters without OP-AMP is brought into high-order.