Slope wave generation circuit as well as digital to analog conversion circuit and fingerprint recognition system thereof

Abstract

The invention discloses a slope wave generation circuit as well as a digital to analog conversion circuit and a fingerprint recognition system thereof, belonging to the field of fingerprint recognition technologies. The slope wave generation circuit comprises an integrating circuit, a signal adjustment circuit and a voltage generation circuit, wherein the integrating circuit is used for outputting a slope wave signal; the signal adjustment circuit comprises a feedback control loop and a transconductance amplifier which are connected in series, the feedback control loop monitors the slope wave signal output by the integrating circuit and outputs an adjustment control signal to the transconductance amplifier, and the transconductance amplifier corrects the slope wave signal output at the next period by the integrating circuit according to the adjustment signal; the voltage generation circuit is used for respectively outputting reference voltage signals to the integrating circuit and the signal adjustment circuit. By adopting the fingerprint recognition system of the invention, the problem of performance deterioration of the fingerprint system, which is caused by influence of PVT (Process Voltage Temperature) on the slope wave generation circuit and a clock generator, can be solved.

Description

technical field [0001] The invention relates to the technical field of fingerprint identification, in particular to a ramp wave generation circuit, a digital-to-analog conversion circuit thereof, and a fingerprint identification system. Background technique [0002] With the development of security technology, fingerprint identification has received more and more attention from people, and its application fields have become wider and wider. The capacitive fingerprint sensing system generally uses the fingerprint sensing pixel (pixel) circuit as the basic unit. The pixel circuit extracts the capacitive coupling signal of each pixel point, and then sends it to other parts of the fingerprint sensing system for amplification, analog-to-digital conversion, image splicing and other operations. Extract valid fingerprint information. The prior art usually adopts the following three methods to deal with the problem of pixel array data reading: global analog-to-digital conversion, lo...

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Problems solved by technology

[0003] In view of this, the technical problem to be solved by the present invention is to provide a ramp wave generation circuit and its digital-to-analog conversion circuit, fingerprint identification system, to solve the problems of the ramp wave generation circuit and clock generator in the prior art due to the influence of PVT. Issues that cause fingerprint system performance to deteriorate

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