Capacitive fingerprint sensor with quadrature demodulator and multiphase scanning
First Claim
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1. A method of detecting a fingerprint, comprising:
- receiving a first signal at a first input terminal, the first signal corresponding to one or more first electrodes of a fingerprint sensor array;
receiving a second signal at a second input terminal, the second signal corresponding to one or more second electrodes of the fingerprint sensor array;
providing, by a sensing circuit, a differential signal based on the first signal and the second signal;
generating, by the sensing circuit, an in-phase component of the differential signal;
generating, by the sensing circuit, a quadrature component of the differential signal; and
generating an output signal representing a capacitance value of the one or more first electrodes using the in-phase component and the quadrature component, wherein the capacitance value is associated with the fingerprint.
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Abstract
A method includes providing a differential signal and generating an in-phase component of the differential signal and a quadrature component of the differential signal. The method further includes generating an output signal representing a capacitance value using the in-phase component and the quadrature component.
48 Citations
20 Claims
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1. A method of detecting a fingerprint, comprising:
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receiving a first signal at a first input terminal, the first signal corresponding to one or more first electrodes of a fingerprint sensor array; receiving a second signal at a second input terminal, the second signal corresponding to one or more second electrodes of the fingerprint sensor array; providing, by a sensing circuit, a differential signal based on the first signal and the second signal; generating, by the sensing circuit, an in-phase component of the differential signal; generating, by the sensing circuit, a quadrature component of the differential signal; and generating an output signal representing a capacitance value of the one or more first electrodes using the in-phase component and the quadrature component, wherein the capacitance value is associated with the fingerprint. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Fingerprint sensing circuitry, comprising:
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a first input circuit to receive a first input signal corresponding to one or more first electrodes of a sensor array; a second input circuit to receive a second input signal corresponding to one or more second electrodes of a fingerprint sensor array; and a sensing circuity coupled to the first and second input circuitry, the sensing circuitry configured to, process a differential signal that is based on the first input signal and the second input signal, generate an in-phase component of the differential signal, generate a quadrature component of the differential signal, and generate an output signal representing a capacitance value of the one or more first electrodes using the in-phase component and the quadrature component, wherein the capacitance value is associated with the fingerprint. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A fingerprint sensing circuitry, comprising:
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a fingerprint sensor comprising an array of sensor electrodes; and a fingerprint controller coupled to the fingerprint sensor, the fingerprint controller comprising, a first circuit configured to couple with one or more first sensor electrodes of the array to receive a first input signal; a second circuit configured to couple with one or more second sensor electrodes of the array to receive a second input signal; and a sensing circuity coupled to the first and second circuits, the sensing circuitry configured to, receive a differential signal that is based on the first input signal and the second input signal, generate an in-phase component of the differential signal, generate a quadrature component of the differential signal, and generate an output signal corresponding to a capacitance value of the array of sensor electrodes and a fingerprint feature, using the in-phase component and the quadrature component. - View Dependent Claims (18, 19, 20)
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Specification