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US 8,416,014 B2Granted
Switched capacitor notch filter with fast response time
AssigneeAllegro MicroSystems, LLC
InventorHernan D. Romero
Life of this patent
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Abstract
A switched capacitor notch filter for sampling an input signal using multiple sampling capacitors during multiple non-overlapping time periods. The charge from one set of sampling capacitors is averaged and transferred to the filter output during one non-overlapping time and the charge from another set of sampling capacitors is averaged and transferred to the filter output during a second non-overlapping time period.
Claims24
A switched capacitor notch filter, comprising:
- an operational amplifier having a first input node coupled to a common node, a second input node, and an output node at which an output signal of the filter is provided;
- a first sampling capacitor having a first terminal selectively coupled to an input node of the switched capacitor notch filter for receiving an input signal by a first switch and having a second terminal selectively coupled to the 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 reference node;
- a second reference switch coupled between the first terminal of the first sampling capacitor and said output node of the operational amplifier;
- a third reference switch coupled between the second terminal of said second sampling capacitor and said reference node;
- a fourth reference switch coupled between the first terminal of the second sampling capacitor and said output node of the operational amplifier;
- a third sampling capacitor having a first terminal selectively coupled to the input signal by a fifth switch and having a second terminal selectively coupled to the common node by a sixth switch;
- a fourth sampling capacitor having a first terminal selectively coupled to the input signal by a seventh switch and having a second terminal selectively coupled to the common node by an eighth switch;
- a fifth reference switch coupled between the second terminal of said third sampling capacitor and said reference node;
- a sixth reference switch coupled between the first terminal of the third sampling capacitor and said output node of the operational amplifier;
- a seventh reference switch coupled between the second terminal of said fourth sampling capacitor and said reference node;
- and
- an eighth reference switch coupled between the first terminal of the fourth sampling capacitor and said output node of the operational amplifier.
11 more elements
A switched capacitor notch filter comprising:
- an operational amplifier having a first input node coupled to a common node, a second input node and an output node at which an output signal of the filter is provided;
- a first set of at least two sampling capacitors selectively coupled between an input node of the switched capacitor notch filter, the output node and the common node, wherein the first set of at least two sampling capacitors is coupled between an input signal received at the input signal and a reference node during a first time period for alternately sampling the input signal during the first time period and is coupled between the common node and the output node of the operational amplifier during a second time period;
- and
- a second set of at least two sampling capacitors selectively coupled between the input node of the switched capacitor notch filter, the output node and the common node, wherein the second set of at least two sampling capacitors is coupled between the input signal and a reference node during the second time period for alternately sampling the input signal during the second time period and is coupled between the common node and the output node of the operational amplifier during the first time period.
1 more element
Dependencies are inferred from the claim text.