A kind of fingerprint recognition dynamic range optimization method and device

Abstract

The invention provides a method for optimizing the dynamic range of an analog-to-digital converter of a fingerprint identification sensor device and a realization circuit, and proposes a specific algorithm for realizing the optimization method. By independently adjusting the gain of the front-end amplifier, the gain and offset of the analog-to-digital converter, the method can maximize the use of the dynamic range of the system, improve the contrast of the fingerprint image, improve the identification performance of fingerprint recognition, and reduce the number of optimization iterations , reducing the fingerprint recognition detection time. The invention proposes a method for adjusting the offset of the analog-to-digital converter. The adjustment of the offset is realized by adjusting the reference voltage at the differential input terminal of the comparator of the analog-to-digital converter. This method can be separated from the gain adjustment of the analog-to-digital converter. Implemented independently, after the offset adjustment is completed, the gain adjustment of the analog-to-digital converter will not affect the offset adjustment result.

Description

technical field [0001] The invention relates to the field of fingerprint identification and processing, in particular to a fingerprint detection and identification method and device. Background technique [0002] Fingerprint detection and recognition technology is a reliable and widely used personal identification verification technology. CMOS fingerprint recognition sensor has the advantages of small size, low power consumption, light and thin modules, etc., and can meet the requirements of miniaturization and low power consumption in the field of mobile terminals, so it is widely used in portable mobile devices, such as mobile phones, tablet devices, PADs, etc. . The capacitive fingerprint recognition sensor has a fingerprint sensing pixel electrode array composed of multiple electrodes, which can respond to the driving signal of the driving circuit and generate a sensing signal based on the change of electrode capacitance. When the finger touches the surface of the senso...

AI Technical Summary

Problems solved by technology

[0006] Existing analog-to-digital converters have the following defects: usually in order to improve the common-mode rejection of the system, the analog-to-digital converter (ADC) generally adopts a differential architecture, for example, the reference voltage of the analog-to-digital converter is V REFH , then the input dynamic range of the analog-to-digital converter (ADC) is [-V REFH , 0] and [0, V REFH ]

Therefore, in the existing fingerprint sensing and identification equipment, the adjustment of the dynamic range of the analog-to-digital converter requires repeated iterative adjustments, resulting in low efficiency, or the problem that the optimal setting cannot be found.

Images