Nxp B.v.

Milind Phadtare

Thomas Suwald

Dillip Kumar Routray

There is described an apparatus for measuring a capacitance formed by a sense plate and a counter plate, wherein the sense plate comprises a first sub-plate and a second sub-plate, the first sub-plate and the second sub-plate being electrically separated. The apparatus comprises (a) a first integrator comprising a first integrator input terminal, a first integrator reference terminal connected to a first reference voltage, and a first integrator output terminal for providing a first output voltage indicative of a capacitance connected to the first integrator input terminal, (b) a second integrator comprising a second integrator input terminal, a second integrator reference terminal coupled to a second reference voltage, and a second integrator output terminal for providing a second output voltage indicative of a capacitance connected to the second integrator input terminal, (c) switching circuitry adapted to, at a first measurement point in time, connect the first integrator input terminal to the first sub-plate and connect the second integrator input terminal to the second sub-plate, and, at a second measurement point in time, connect the first integrator input terminal to the second sub-plate and connect the second integrator input terminal to the first sub-plate, and (d) output circuitry coupled to the first integrator output terminal and the second integrator output terminal and adapted to generate an output signal based on a difference between the first output voltage and the second output voltage, the output signal being indicative of the capacitance formed by the sense plate and the counter plate. There is also described a fingerprint sensor and a method.

Apparatus and method for measuring a capacitance, and a fingerprint sensor utilizing the same

In accordance with a first aspect of the present disclosure, a fingerprint sensing device is provided, comprising a plurality of sensor cells, wherein each sensor cell comprises: at least one sense plate and a discharge electrode insulated from the sense plate; a first discharge path for discharging a first static electricity charge to a first electric potential terminal; a second discharge path for discharging a second static electricity charge to a second electric potential terminal; a charge reservoir coupled between the first electric potential terminal and the second electric potential terminal. In accordance with a second aspect of the present disclosure, a corresponding method of producing a fingerprint sensing device is conceived.

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Bengaluru, India

Milind Phadtare