Invention Grant
- Patent Title: Finger biometric sensing device including series coupled error compensation and drive signal nulling circuitry and related methods
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Application No.: US15787200Application Date: 2017-10-18
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Publication No.: US10049255B2Publication Date: 2018-08-14
- Inventor: Pavel Mrazek , Giovanni Gozzini , Jean-Marie Bussat
- Applicant: APPLE INC.
- Applicant Address: US CA Cupertino
- Assignee: APPLE INC.
- Current Assignee: APPLE INC.
- Current Assignee Address: US CA Cupertino
- Agency: Allen, Dyer, Doppelt + Gilchrist, P.A., Attorneys at Law
- Main IPC: G06K9/00
- IPC: G06K9/00 ; H03G3/30

Abstract:
A finger biometric sensing device may include drive circuitry for generating a drive signal and an array of finger biometric sensing pixel electrodes cooperating with the drive circuitry and generating a detected signal based upon placement of a finger adjacent the array. The detected signal may include a drive signal component and a sense signal component superimposed thereon. A gain stage may be coupled to the array and drive signal nulling circuitry may be coupled to the gain stage for reducing the drive signal component from the detected signal. The drive signal nulling circuitry may include a first digital-to-analog converter (DAC) generating an inverted scaled replica of the drive signal for the gain stage. Error compensation circuitry includes a memory storing error compensation data and a second DAC coupled in series with the first DAC compensating an error in the inverted scaled replica based upon the error compensation data.
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