CAPACITANCE TO CODE CONVERTER WITH SIGMA-DELTA MODULATOR
First Claim
1. A method comprising:
- measuring a mutual capacitance on a sense element of a matrix-scanning device using a modulation circuit, wherein the matrix-scanning device comprises a plurality of drive lines and a plurality of sense lines and the sense element is located at an intersection of one of the plurality of drive lines and one of the plurality of sense lines; and
switching the sense element to be coupled and decoupled to a capacitor of the modulation circuit using a first plurality of switches, wherein the first plurality of switches are controlled by a clock;
converting the mutual capacitance measured on the sense element to a first digital value;
measuring a self-capacitance on at least one of the plurality of drive lines;
switching the at least one of the plurality of drive lines to be coupled and decoupled to the capacitor using a second plurality of switches, wherein the second plurality of switches are controlled by the clock; and
converting the self-capacitance measured on the at least one of the plurality of drive lines to a second digital value.
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Accused Products
Abstract
An apparatus and method of converting a capacitance measured on a sensor element to a digital value. The apparatus may include a matrix-scanning device including drive lines and sense lines. A sense element is located at an intersection of one of the drive lines and one of the sense lines. The apparatus also includes a modulation circuit coupled to the drive lines and the sense lines, and a switching circuit having first switches controlled by a clock. The modulation circuit is configured to measure a mutual capacitance on the sense element and to convert the measured mutual capacitance to a first digital value. The modulation circuit is configured to measure a self-capacitance on at least one of the drive lines and to convert the measured self-capacitance to a second digital value.
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Citations
23 Claims
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1. A method comprising:
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measuring a mutual capacitance on a sense element of a matrix-scanning device using a modulation circuit, wherein the matrix-scanning device comprises a plurality of drive lines and a plurality of sense lines and the sense element is located at an intersection of one of the plurality of drive lines and one of the plurality of sense lines; and switching the sense element to be coupled and decoupled to a capacitor of the modulation circuit using a first plurality of switches, wherein the first plurality of switches are controlled by a clock; converting the mutual capacitance measured on the sense element to a first digital value; measuring a self-capacitance on at least one of the plurality of drive lines; switching the at least one of the plurality of drive lines to be coupled and decoupled to the capacitor using a second plurality of switches, wherein the second plurality of switches are controlled by the clock; and converting the self-capacitance measured on the at least one of the plurality of drive lines to a second digital value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus, comprising:
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a matrix-scanning device comprising a plurality of drive lines and a plurality of sense lines and a sense element is located at an intersection of one of the plurality of drive lines and one of the plurality of sense lines; a modulation circuit selectively coupled to the plurality of drive lines and the plurality of sense lines; and a switching circuit having a first plurality of switches and a second plurality of switches controlled in response to a clock, wherein the modulation circuit is configured to measure a mutual capacitance on the sense element using the first plurality of switches, wherein the modulation circuit is configured to convert the measured mutual capacitance to a first digital value, wherein the modulation circuit is configured to measure a self-capacitance on at least one of the plurality of drive lines using the second plurality of switches, and wherein the modulation circuit is configured to convert the self-capacitance to a second digital value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A system, comprising:
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a matrix-scanning device comprising a plurality of sense elements, wherein the plurality of sense elements are intersections between a plurality of drive lines and a plurality of sense lines of the matrix-scanning device; a processing device coupled to the matrix-scanning device, the processing device comprising; a switching circuit having a first plurality of switches and a second plurality of switches, wherein the processing device is configured to control the first and second plurality of switches using a clock; and a modulation circuit configured to be coupled to the plurality of drive lines and the plurality of sense lines, wherein the modulation circuit is configured to measure a mutual capacitance on the one sense element using the first plurality of switches, wherein the modulation circuit is configured to convert the measured mutual capacitance to a first digital value, wherein the modulation circuit is configured to measure a self-capacitance on at least one of the plurality of drive line using the second plurality of switches, and wherein the modulation circuit is configured to convert the measured self-capacitance to a second digital value. - View Dependent Claims (21, 22, 23)
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Specification