Invention Grant
- Patent Title: Analog sampling system and method for noise supression
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Application No.: US15196617Application Date: 2016-06-29
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Publication No.: US09600707B1Publication Date: 2017-03-21
- Inventor: Fredrik Ramberg , Hans Thörnblom , David Carling , Frank Robert Riedijk
- Applicant: Fingerprint Cards AB
- Applicant Address: SE Göteborg
- Assignee: FINGERPRINT CARDS AB
- Current Assignee: FINGERPRINT CARDS AB
- Current Assignee Address: SE Göteborg
- Agency: Remarck Law Group PLC
- Priority: SE1551553-9 20151130
- Main IPC: G06F3/045
- IPC: G06F3/045 ; G06K9/00

Abstract:
There is provided a capacitive fingerprint sensing device comprising a plurality of sensing elements, sensing circuitry for providing an analog sensing signal, drive signal circuitry providing a drive signal comprising a drive pulse having a maximum level and a minimum level, providing a change in potential difference between the finger and the sensing structure, analog sampling circuitry comprising at least three analog sample and hold circuits arranged to sample the sensing signal, and a sampling control unit for individually controlling the sample and hold circuits to capture a sample at a specified time, wherein the samples comprises one sample captured when the drive signal is at a first voltage level V1 and one sample captured when the drive signal is at a second voltage level V2, different from V1; and an analog-to-digital converter, ADC, configured to convert a combination of the samples into a digital signal, wherein the three samples are captured times such that a noise component is suppressed from the sensing signal when the combination is formed.
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