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US 2012/0268145 A1Published application
Current sensing apparatus and method for a capacitance-sensing device
AssigneeCypress Semiconductor Corporation
InventorsLokesh Chandra, Edward Grivna
Life of this patent
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Abstract
A capacitance-sensing device including a current-to-voltage converter and an analog-to-digital converter is described. A sense element is coupled to an input of the current-to-voltage converter. The current-to-voltage converter is configured to convert current changes in the coupled sense element to an output voltage and to maintain a constant voltage at the input. The analog-to-digital converter is configured to convert the output voltage generated by the current-to-voltage converter to a digital value.
Claims20
An apparatus, comprising:
- a current-to-voltage converter having an input coupled to receive a current representing a capacitance of a sense element, wherein the current-to-voltage converter is configured to convert the current to an output voltage;
- and
- an analog-to-digital converter (ADC) coupled to receive the output voltage of the current-to-voltage converter, wherein the ADC is configured to convert the output voltage to a digital value, and wherein the current-to-voltage converter is configured to maintain an approximately constant voltage at the input of the current-to-voltage converter.
A method, comprising:
- sensing current changes in a sense element coupled to an input of a capacitance-sensing device;
- converting the sensed current changes to an output voltage by the capacitance-sensing device;
- and
- measuring capacitance changes of the sense element by converting the output voltage to a digital value.
1 more element
An apparatus, comprising:
- means for sensing current changes in a sense element coupled to an input of a capacitance-sensing device;
- means for converting the sensed current changes to an output voltage by the capacitance-sensing device;
- and
- means for measuring capacitance changes of the sense element by converting the output voltage to a digital value;
- and
- means for maintaining a constant voltage at the input of the capacitance-sensing device.
3 more elements
Dependencies are inferred from the claim text.