Capacitive charge measurement
First Claim
1. A circuit for measuring a capacitive charge, said circuit comprising:
- a latched comparator, wherein said latched comparator comprises;
an input coupled with a sensor electrode of a capacitive input device;
an output; and
an inverted version of the output coupled with a feedback loop, said feedback loop configured to provide feedback to said input to maintain said input at a predetermined voltage, wherein said feedback is provided in clocked charge quanta steps based on a clock signal; and
a determination module coupled with said output and configured to determine a change in capacitance on said sensor electrode by equating output signals from said output with an amount of charge provided to said input to reach said predetermined voltage.
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Accused Products
Abstract
A circuit for measuring a capacitive charge comprises a latched comparator and a determination module. The latched comparator comprises an input and an output. The input is coupled with a sensor electrode of a capacitive input device. An inverted version of the output is coupled with a feedback loop. The feedback loop is configured to provide feedback to the input to maintain the input at a predetermined voltage. The feedback is provided in clocked charge quanta steps based on a clock signal. The determination module is coupled with the output and configured to determine a change in capacitance on the sensor electrode by equating output signals from the output with an amount of charge provided to the input to reach the predetermined voltage.
61 Citations
21 Claims
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1. A circuit for measuring a capacitive charge, said circuit comprising:
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a latched comparator, wherein said latched comparator comprises; an input coupled with a sensor electrode of a capacitive input device; an output; and an inverted version of the output coupled with a feedback loop, said feedback loop configured to provide feedback to said input to maintain said input at a predetermined voltage, wherein said feedback is provided in clocked charge quanta steps based on a clock signal; and a determination module coupled with said output and configured to determine a change in capacitance on said sensor electrode by equating output signals from said output with an amount of charge provided to said input to reach said predetermined voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A processing system for a capacitive input device, said processing system comprising:
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a receiver module comprising; an input configured to be maintained at a predetermined voltage, wherein said input is coupled with a receiver electrode of said capacitive input device; an output; and an inverted version of said output coupled to said input; and a determination module coupled with said output and configured to determine a change in capacitance on said receiver electrode by equating output signals from said output with an amount of charge provided in feedback to said input to reach said predetermined voltage. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A capacitive input device comprising:
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a plurality of sensor electrodes; and a processing system coupled with said plurality of sensor electrodes, said processing system comprising; a transmitter module configured to drive a transmitter electrode of said plurality of sensor electrodes with a transmitter signal; a receiver module comprising; an input configured to be maintained at a predetermined voltage, wherein said input is coupled with a receiver electrode of said plurality of sensor electrodes; an output; and an inverted version of said output coupled to said input; and a determination module coupled with said output and configured to determine a change in capacitance on said receiver electrode by equating output signals from said output with an amount of charge provided in feedback to said input to reach said predetermined voltage. - View Dependent Claims (19, 20, 21)
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Specification