Multi-functional capacitance sensing circuit with a current conveyor
First Claim
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1. An apparatus, comprising:
- a capacitance sensing circuit comprising a current conveyor and a mode selection circuit, the capacitance sensing circuit configured to sense capacitance of one or more sensor elements in a plurality of capacitance sensing modes, wherein a first of the plurality of capacitance sensing modes is a self-capacitance sensing mode, and a second of the plurality of capacitance sensing modes is a mutual capacitance sensing mode;
wherein an output of the mode selection circuit is coupled to a voltage input of the current conveyor; and
wherein the mode selection circuit is configured to switch between the self-capacitance sensing mode and the mutual capacitance sensing mode.
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Abstract
An apparatus for and a method of sensing capacitance of one or more sensor elements in multiple capacitance sensing modes, including a self-capacitance sensing mode and a mutual capacitance sensing mode.
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15 Claims
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1. An apparatus, comprising:
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a capacitance sensing circuit comprising a current conveyor and a mode selection circuit, the capacitance sensing circuit configured to sense capacitance of one or more sensor elements in a plurality of capacitance sensing modes, wherein a first of the plurality of capacitance sensing modes is a self-capacitance sensing mode, and a second of the plurality of capacitance sensing modes is a mutual capacitance sensing mode; wherein an output of the mode selection circuit is coupled to a voltage input of the current conveyor; and wherein the mode selection circuit is configured to switch between the self-capacitance sensing mode and the mutual capacitance sensing mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of measuring capacitance, comprising:
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applying a mode selection signal to a mode selection circuit of a capacitance sensing circuit; the mode selection circuit selecting one of a plurality of capacitance sensing modes, wherein a first of the plurality of capacitance sensing modes is a self-capacitance sensing mode, and a second of the plurality of capacitance sensing modes is a mutual capacitance sensing mode; the mode selection circuit applying an output to a voltage input of a current conveyor of the capacitance sensing circuit, wherein the output is a clock signal when self-capacitance sensing mode is selected, and wherein the output is a constant reference voltage when the mutual capacitance sensing mode is selected; and sensing capacitance of one or more sensor elements based on the selected one of the plurality of capacitance sensing modes. - View Dependent Claims (10, 11, 12, 13)
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- 14. An apparatus, comprising a capacitance sensing circuit comprising a current conveyor and a mode selection circuit, the capacitance sensing circuit configured to sense capacitance of a sensor element in a self-capacitance sensing mode, wherein when in the self-capacitance sensing mode the capacitance sensing circuit is configured to detect a proximity of an object to one or more sensor elements, wherein an output of the mode selection circuit is coupled to a voltage input of the current conveyor, and wherein the mode selection circuit is configured to select the self-capacitance sensing mode in response to a selection signal.
Specification