Finger biometric sensing device including drive signal nulling circuitry and related methods
First Claim
1. A finger biometric sensing device comprising:
- drive circuitry capable of generating a drive signal and comprising a finger coupling electrode to couple a drive signal to a finger and a voltage generator coupled to said finger coupling electrode;
an array of finger biometric sensing pixel electrodes adjacent said finger coupling electrode, cooperating with said drive circuitry, and capable of generating a detected signal based upon placement of the finger adjacent said array of finger biometric sensing pixel electrodes, the detected signal including a relatively large drive signal component based upon the drive signal and a relatively small sense signal component superimposed thereon, the relatively small sense signal component comprising finger biometric characteristic data for performing an authentication function;
at least one gain stage coupled to said array of finger biometric sensing pixel electrodes; and
drive signal nulling circuitry coupled to said at least one gain stage capable of reducing the relatively large drive signal component from the detected signal.
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Abstract
A finger biometric sensing device may include drive circuitry capable of generating a drive signal and an array of finger biometric sensing pixel electrodes cooperating with the drive circuitry and capable of generating a detected signal based upon placement of a finger adjacent the array of finger biometric sensing pixel electrodes. The detected signal may include a relatively large drive signal component and a relatively small sense signal component superimposed thereon. The finger biometric sensing device may also include a gain stage coupled to the array of finger biometric sensing pixel electrodes, and drive signal nulling circuitry coupled to the gain stage capable of reducing the relatively large drive signal component from the detected signal.
39 Citations
23 Claims
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1. A finger biometric sensing device comprising:
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drive circuitry capable of generating a drive signal and comprising a finger coupling electrode to couple a drive signal to a finger and a voltage generator coupled to said finger coupling electrode; an array of finger biometric sensing pixel electrodes adjacent said finger coupling electrode, cooperating with said drive circuitry, and capable of generating a detected signal based upon placement of the finger adjacent said array of finger biometric sensing pixel electrodes, the detected signal including a relatively large drive signal component based upon the drive signal and a relatively small sense signal component superimposed thereon, the relatively small sense signal component comprising finger biometric characteristic data for performing an authentication function; at least one gain stage coupled to said array of finger biometric sensing pixel electrodes; and drive signal nulling circuitry coupled to said at least one gain stage capable of reducing the relatively large drive signal component from the detected signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A finger biometric sensing device comprising:
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drive circuitry capable of generating a drive signal and comprising a finger coupling electrode to couple a drive signal to a finger and a voltage generator coupled to said finger coupling electrode; an array of finger biometric sensing pixel electrodes adjacent said finger coupling electrode, cooperating with said drive circuitry, and capable of generating a detected signal based upon placement of the finger adjacent said array of finger biometric sensing pixel electrodes, the detected signal including a relatively large drive signal component based upon the drive signal and a relatively small sense signal component superimposed thereon, the relatively small sense signal component comprising finger biometric characteristic data for performing an authentication function; a dielectric layer covering said array of finger biometric sensing pixel electrodes; at least one gain stage coupled to said array of finger biometric sensing pixel electrodes; and a digital-to-analog converter (DAC) capable of generating an inverted scaled replica of the drive signal for said at least one gain stage thereby reducing the relatively large drive signal component from the detected signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method of reducing a relatively large drive signal in a finger biometric sensing device comprising drive circuitry capable of generating a drive signal and comprising a finger coupling electrode to couple a drive signal to a finger and a voltage generator coupled to the finger coupling electrode, and an array of finger biometric sensing pixel electrodes adjacent the finger coupling electrode, cooperating with the drive circuitry, and capable of generating a detected signal based upon placement of the finger adjacent the array of finger biometric sensing pixel electrodes, the detected signal including a relatively large drive signal component based upon the drive signal and a relatively small sense signal component superimposed thereon, the relatively small sense signal component comprising finger biometric characteristic data for performing an authentication function, and at least one gain stage coupled to the array of finger sensing biometric pixel electrodes, the method comprising:
operating drive signal nulling circuitry coupled to the at least one gain stage to reduce the relatively large drive signal component from the detected signal. - View Dependent Claims (20, 21, 22, 23)
Specification