Patent ID: 7990209

Claim:
A switched capacitor notch filter to remove unwanted components within a predetermined frequency range of an input signal, comprising: a first sampling capacitor having a first terminal selectively coupled to the input signal by a first switch and having a second terminal selectively coupled to a common node by a second switch; a second sampling capacitor having a first terminal selectively coupled to the input signal by a third switch and having a second terminal selectively coupled to the common node by a fourth switch; a first reference switch coupled between the second terminal of said first sampling capacitor and a first reference node; a second reference switch coupled between the first terminal of the first sampling capacitor and a second reference node; a third reference switch coupled between the second terminal of said second sampling capacitor and said first reference node; a fourth reference switch coupled between the first terminal of the second sampling capacitor and said second reference node; an operational amplifier having a first input node coupled to the common node, a second input node, and an output node at which a filtered signal of the filter is provided; a first feedback capacitor coupled between the output node and the first input node of the operational amplifier; and a clock signal generator for providing a first clock signal to close the first switch and the first reference switch during a first portion of each clock cycle, a second, non-overlapping clock signal to close the third switch and the third reference switch during a second non-overlapping portion of each clock cycle and an averaging, non-overlapping clock signal to close the second switch, fourth switch, second reference switch, and fourth reference switch during a third non-overlapping portion of each clock cycle, wherein the input signal is not sampled during the third portion of each clock cycle.