Receive demodulator for capacitive sensing
First Claim
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1. A method, comprising:
- detecting a current flowing at a terminal of a capacitance sensing element;
coupling the current to a charge storage circuit to generate a first output voltage signal and a second output voltage signal; and
detecting a presence of a conductive object proximate to the capacitance sensing element based on a difference between the first output voltage signal and the second output voltage signal.
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Abstract
A first integration capacitor stores charge from a positive signal portion. A second integration capacitor stores charge from negative signal portion. The voltage across the first and second integration capacitors is measured differentially. The presence of a conductive object proximate to a capacitance sensing element is detected based on the measured differential voltage between the first and second integration capacitors.
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Citations
20 Claims
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1. A method, comprising:
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detecting a current flowing at a terminal of a capacitance sensing element; coupling the current to a charge storage circuit to generate a first output voltage signal and a second output voltage signal; and detecting a presence of a conductive object proximate to the capacitance sensing element based on a difference between the first output voltage signal and the second output voltage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus, comprising:
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a terminal coupled to an electrode of a capacitive sensing device; a coupling circuit coupled to the electrode of the capacitive sensing device; and a charge storage circuit coupled to the coupling circuit, wherein the charge storage circuit is configured to generate a first output voltage signal from a first portion of the signal received from the electrode and a second output voltage signal from a second portion of the signal received from the electrode for a detection of a presence of a conductive object proximate to the capacitive sensing device based on a difference between the first output voltage signal and the second output voltage signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method, comprising:
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charging a first integration capacitor with a positive signal portion of a signal received from an electrode of a capacitive sensing device; charging a second integration capacitor with a negative signal portion of the signal received from the electrode of the capacitive sensing device; measuring a differential voltage between the first and second integration capacitors; and detecting a presence of a conductive object proximate to the capacitive sensing device based on the measured differential voltage. - View Dependent Claims (19, 20)
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Specification