PROVIDING A BASELINE CAPACITANCE FOR A CAPACITANCE SENSING CHANNEL
First Claim
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1. A capacitance-sensing circuit comprising:
- a channel input associated with measuring a capacitance of a unit cell of a capacitive sense array; and
a capacitive hardware baseliner coupled to the channel input, the capacitive hardware baseliner to generate a baseline current based on a time constant of the channel input associated with the measuring of the capacitance of the unit cell of the capacitive sense array using a baseline capacitor, wherein the capacitive hardware baseliner to provide the baseline current to the channel input to provide a charge for a sense capacitor, wherein a change in the charge of the sense capacitor that is provided by the baseline current indicates a presence of a touch object proximate to the unit cell.
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Abstract
A capacitance-sensing circuit may include a channel input associated with measuring a capacitance of a unit cell of a capacitive sense array. The capacitance-sensing circuit may also include a capacitive hardware baseliner that is coupled to the channel input. The capacitive hardware baseliner may generate a baseline current using a baseline capacitor and may provide the baseline current to the channel input.
70 Citations
20 Claims
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1. A capacitance-sensing circuit comprising:
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a channel input associated with measuring a capacitance of a unit cell of a capacitive sense array; and a capacitive hardware baseliner coupled to the channel input, the capacitive hardware baseliner to generate a baseline current based on a time constant of the channel input associated with the measuring of the capacitance of the unit cell of the capacitive sense array using a baseline capacitor, wherein the capacitive hardware baseliner to provide the baseline current to the channel input to provide a charge for a sense capacitor, wherein a change in the charge of the sense capacitor that is provided by the baseline current indicates a presence of a touch object proximate to the unit cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method comprising:
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generating, by a capacitive baseline circuit associated with a capacitive sense array, an output current based on a capacitance value of a capacitor and a time constant of a channel input of the capacitive sense array; applying a gain factor to the output current to generate a baseline current; and providing the baseline current to a channel input associated with the capacitive sense array to provide a charge for a sense capacitor, wherein a change in the charge of the sense capacitor that is provided by the baseline current indicates a presence of a touch object at the capacitive sense array. - View Dependent Claims (15)
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16. A capacitive sense array system comprising:
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a plurality of unit cells, each unit cell comprising an electrode or a pair of electrodes; a plurality of channel inputs to measure capacitances of the plurality of unit cells; and a capacitive hardware baseliner coupled to the plurality of channel inputs, the capacitive hardware baseliner to generate a plurality of baseline currents based on a time constant of the channel inputs associated with the measuring of the capacitances of the unit cells of the capacitive sense array using a baseline capacitor, wherein the capacitive hardware baseliner to provide the plurality of baseline currents to the plurality of channel inputs to provide a charge for a plurality of sense capacitors, wherein a change in one of the sense capacitors that is provided by the baseline current indicates a presence of a touch object proximate to the corresponding unit cell. - View Dependent Claims (17, 18, 19, 20)
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Specification