Patent ID: 8111741

Claim:
A sampling filter apparatus, the filter characteristic of which is determined in response to an output from an integrator, the apparatus comprising: “N” pieces (symbol “N” is an integer larger than or equal to 2) of voltage/current converters which convert an input voltage into predetermined currents; “N+1” pieces of integrators which integrate the currents outputted from the voltage/current converters to output the integrated current; “N+1” pieces of charging switches which are provided at respective input stages of the “N+1” pieces of integrators; “N+1” pieces of discharging switches which are provided at respective output stages of the “N+1” pieces of integrators; a selecting switch which switches connections between the “N” pieces of voltage/current converters and the “N+1” pieces of charging switches; and a controller which controls ON timing and OFF timing as to the “N+1” pieces of charging switches and the “N+1” pieces of discharging switches respectively with respect to each of the integrators, and controls timing of switching the connections by the selecting switch, wherein the controller controls the ON timing and the OFF timing as to the charging switches and the discharging switches such that electric charges are charged from the “N” pieces of voltage/current converters into “N” pieces of the integrators selected from the “N+1” pieces of integrators, and at the same time, an electric charge is discharged from “1” piece of the integrator other than the “N” pieces of selected integrators.