Switched capacitor filter circuit employing two switched capacitor filters

摘要

A switched capacitor filter circuit which enables easy adjustment of a post-filter circuit to reduce the power consumption of a switched capacitor filter at a main side. In the switched capacitor filter circuit, a plurality of capacitors having capacitive values weighted by interpolating operation coefficients are provided, and a second SCF, operated at a sufficiently high sampling frequency to suppress unnecessary frequency components through a lower-order analog filter, is used as a post-filter. Further an output of a first SCF at the main side is simultaneously stored in the plurality of capacitors at in the form of charges stored therein so that the charges are sequentially extracted at equi-intervals of a sampling frequency higher than that of the first SCF to perform non-cyclic filtering operation, whereby higher-order interpolating operation of an output of the first SCF is carried out to suppress unnecessary frequency components corresponding to a multiple of the sampling frequency contained in the first SCF output.