PURPOSE: To eliminate the need for the analog pre-filter and postfilter having been required for a conventional circuit by providing the roll of the pre-filter and post-filter of a consecutive time system filter on a block being a part in the switched capacitor filter.
CONSTITUTION: At least a primary or secondary block of a first stage and a last stage in the switched capacitor filter(SCF) 14 having a main characteristic is constituted by an analog filter 12 using a MOS transistor as a resistor. The analog filter 12 uses the MOSFET as a resistor and it is set to a required resistance by a resistance calibration circuit 13 as a bias voltage calibration circuit being the gate-source circuit. Thus, the pre-filter and the post-filter having a cut-off frequency of fs/2 are not required in the filter circuit of this invention.
| JPH09199994 | SWITCHED CAPACITOR FILTER |
| JP2010268135 | FILTER CIRCUIT AND COMMUNICATION DEVICE |
| WO/2005/071836 | LOW-PASS CIRCUIT |
MUROTA KAZUAKI
TANAKA YUKIO
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