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US 8,575,947 B1Granted
Receive demodulator for capacitive sensing
AssigneeCypress Semiconductor Corporation
InventorsPaul Walsh, Zheyao Zhang, Viktor Kremin
Life of this patent
Estimating the term…
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.
Claims20
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.
1 more element
An apparatus, comprising:
- 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.
1 more element
A method, comprising:
- 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.
2 more elements
Dependencies are inferred from the claim text.