Methods and circuits for measuring mutual and self capacitance
First Claim
1. A capacitance measurement circuit, comprising:
- a plurality of switches;
a first node coupled with a first electrode and coupled with at least a first switch of the plurality of switches; and
a second node coupled with a second electrode and coupled with at least a second switch of the plurality of switches, wherein the plurality of switches is configured to reduce an influence of a self-capacitance of the first electrode and a self-capacitance of the second electrode on an output signal during measurement of a mutual capacitance between the first electrode and the second electrode, and wherein the plurality of switches is configured to reduce an influence of the mutual capacitance on the output signal during measurement of at least one of the self-capacitance of the first electrode and the self-capacitance of the second electrode.
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Abstract
An embodiment of a capacitance measurement circuit may include multiple switches, a first node coupled with a first electrode and coupled with at least a first switch of the multiple switches, and a second node coupled with a second electrode and coupled with at least a second switch of the multiple switches, where the multiple switches are configured to reduce an influence of a self-capacitance of the first electrode and a self-capacitance of the second electrode on an output signal during measurement of a mutual capacitance between the first electrode and the second electrode, and where the multiple switches are configured to reduce an influence of the mutual capacitance on the output signal during measurement of at least one of the self-capacitance of the first electrode and the self-capacitance of the second electrode.
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Citations
20 Claims
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1. A capacitance measurement circuit, comprising:
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a plurality of switches; a first node coupled with a first electrode and coupled with at least a first switch of the plurality of switches; and a second node coupled with a second electrode and coupled with at least a second switch of the plurality of switches, wherein the plurality of switches is configured to reduce an influence of a self-capacitance of the first electrode and a self-capacitance of the second electrode on an output signal during measurement of a mutual capacitance between the first electrode and the second electrode, and wherein the plurality of switches is configured to reduce an influence of the mutual capacitance on the output signal during measurement of at least one of the self-capacitance of the first electrode and the self-capacitance of the second electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A capacitance measurement circuit, comprising:
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a first node coupled with a first electrode; a second node coupled with a second electrode capacitively coupled with the first electrode; and a plurality of switches coupled with the first node and the second node and configured to reduce an influence of a mutual capacitance on an output signal by operating according to a first switching sequence during measurement of a self-capacitance for at least one of the first electrode and the second electrode, and configured to reduce an influence of the self-capacitance of the first electrode and the self-capacitance of the second electrode on the output signal by operating according to a second switching sequence different from the first sequence during measurement of the mutual capacitance between the first electrode and the second electrode. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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operating a plurality of switches according to a first switching sequence to reduce an influence of a mutual capacitance between a pair of electrodes for a period of time during which a self-capacitance is measured for at least one of the pair of electrodes; and operating the plurality of switches according to a second switching sequence to reduce an influence of self-capacitances for each of the pair of electrodes for a period of time during which the mutual capacitance between the pair of electrodes is measured. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification