WO2017016102A1 - 指纹检测电路及指纹辨识系统 - Google Patents

指纹检测电路及指纹辨识系统 Download PDF

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Publication number
WO2017016102A1
WO2017016102A1 PCT/CN2015/094638 CN2015094638W WO2017016102A1 WO 2017016102 A1 WO2017016102 A1 WO 2017016102A1 CN 2015094638 W CN2015094638 W CN 2015094638W WO 2017016102 A1 WO2017016102 A1 WO 2017016102A1
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Prior art keywords
inverting amplifier
transistor
conductive layer
fingerprint
coupled
Prior art date
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PCT/CN2015/094638
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English (en)
French (fr)
Inventor
詹昶
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Shenzhen Goodix Technology Co Ltd
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Shenzhen Huiding Technology Co Ltd
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Priority to EP15899454.1A priority Critical patent/EP3239893B1/en
Priority to KR1020177022804A priority patent/KR20170104585A/ko
Publication of WO2017016102A1 publication Critical patent/WO2017016102A1/zh
Priority to US15/659,564 priority patent/US10346666B2/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/1347—Preprocessing; Feature extraction
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/1365—Matching; Classification
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/96—Touch switches
    • H03K17/962—Capacitive touch switches

Definitions

  • the invention belongs to the technical field of fingerprint detection, and relates to a fingerprint detection circuit and a fingerprint identification system, in particular to a fingerprint detection circuit and a fingerprint identification system with high accuracy and simple circuit structure.
  • portable electronic devices such as mobile phones, digital cameras, tablets and notebook computers have become an indispensable tool in people's lives. Since portable electronic devices are generally used for personal use, they have a certain degree of privacy, and internally stored data such as a phone book, photos, personal information, and the like are privately owned. If the electronic device is lost, the data may be used by others, causing unnecessary losses.
  • password protection has been used to prevent electronic devices from being used by others, passwords are easily leaked or cracked, and have low security. And the user needs to remember the password to use the electronic device, and if the password is forgotten, it will bring a lot of inconvenience to the user. Therefore, the use of personal fingerprinting to achieve identity authentication has been developed to improve data security.
  • a capacitive fingerprint recognition system is a popular fingerprint identification method, which uses a sensing capacitance to determine a Finger Ridge or a Finger Valley of a user's fingerprint.
  • the capacitive fingerprint identification system uses a metal electrode to receive a user's finger contact.
  • the fingerprint detection circuit in the capacitive fingerprint recognition system converts the capacitance between the metal electrode and the user's finger into a voltage signal, and outputs it to the voltage signal.
  • the fingerprint judgment module of the back end for fingerprint recognition The fingerprint judgment module of the back end for fingerprint recognition.
  • the fingerprint detection circuit in the capacitive fingerprint identification system usually requires a complicated bias circuit to ensure that the fingerprint detection circuit can operate correctly (ie, the DC bias operating point of the fingerprint detection circuit is in an appropriate area), which is too simple.
  • the bias circuit affects the accuracy of the fingerprint detection circuit. Therefore, how to provide a fingerprint detection circuit with high accuracy and simple circuit structure has become one of the goals of the industry.
  • the object of the present invention is to provide a fingerprint detecting circuit and a fingerprint identification system, which aim to improve the accuracy of fingerprint detection and the circuit structure is simple.
  • a fingerprint detecting circuit includes:
  • the inverting amplifier includes: only one input end coupled to the first conductive layer; and an output end coupled to the second conductive layer;
  • a switching unit configured to establish a DC operating point of the inverting amplifier, one end of the switching unit is coupled to an input end of the inverting amplifier, and the other end of the switching unit is coupled to the inverting amplifier Output.
  • It is also an object of the present invention to provide a fingerprint identification system comprising:
  • a plurality of fingerprint detecting circuits each of which includes:
  • the inverting amplifier includes: only one input end coupled to the first conductive layer; and an output end coupled to the second conductive layer;
  • a switching unit configured to establish a DC operating point of the inverting amplifier, one end of the switching unit is coupled to an input end of the inverting amplifier, and the other end of the switching unit is coupled to the inverting amplifier Output
  • the fingerprint determination module is coupled to the plurality of fingerprint detection circuits for determining that each fingerprint detection circuit corresponds to a Finger Ridge or a Finger Valley.
  • the embodiment of the invention utilizes a single-ended input single-ended output inverting amplifier, and uses the switching unit to quickly and correctly establish the DC bias operating point of the inverting amplifier, and accurately converts the capacitance value of the sensing capacitor into an output signal. There is no need to configure an additional bias circuit, and the circuit structure is simple and accurate.
  • FIG. 1 is a schematic diagram of a fingerprint detecting circuit according to Embodiment 1 of the present invention.
  • FIG. 2 is an equivalent circuit diagram of the fingerprint detecting circuit of FIG. 1;
  • Figure 3 is a schematic diagram of the inverting amplifier of Figure 1;
  • FIG. 4 is a schematic diagram showing voltage conversion characteristics of the inverting amplifier of FIG. 3;
  • FIG. 5 is a schematic diagram of a fingerprint identification system according to Embodiment 2 of the present invention.
  • FIG. 1 is a schematic diagram of a fingerprint detecting circuit 10 according to an embodiment of the present invention.
  • the fingerprint detecting circuit 10 includes an inverting amplifier 104, a switching unit SW, and conductive layers 100, 102.
  • the conductive layer 100 is a top conductive layer, which may be a metal electrode or a metal layer of an integrated circuit layout for receiving contact of the finger FG.
  • the conductive layer 102 is a lower conductive layer, which may be a metal electrode, a metal layer or a polysilicon layer (Poly) of an integrated circuit layout.
  • the conductive layer 102 is disposed under the conductive layer 100, a reference capacitance Cf is formed between the conductive layer 100 and the conductive layer 102, and the conductive layer 100 and the finger FG are formed with a sensing capacitance Cs.
  • the inverting amplifier 104 is a single-ended single-output (Single Input Single Output) amplifier, which includes a single input terminal and an output terminal. The input end of the inverting amplifier 104 is coupled to the conductive layer 100, and the output end is coupled to the conductive layer 102. .
  • the switching unit SW is configured to establish a DC bias voltage of the inverting amplifier 104. One end of the switching unit SW is coupled to the input end of the inverting amplifier 104, and the other end of the switching unit SW is coupled to the output end of the inverting amplifier 104.
  • the capacitance value of the reference capacitor Cf depends on the area of the conductive layer 102.
  • the capacitance value of the reference capacitor Cf is a fixed capacitance value.
  • the capacitance value of the sensing capacitor Cs varies with the fingerprint characteristics of the finger FG.
  • the finger FG can pass through gold
  • the genus electrode receives the driving signal Vs, and the driving signal Vs is coupled to the input end of the inverting amplifier 104 through the sensing capacitor Cs, that is, after the driving signal Vs passes through the sensing capacitor Cs, an input signal Vi is formed at the input end of the inverting amplifier 104.
  • the inverting amplifier 104 receives the input signal Vi to generate the output signal Vo.
  • the fingerprint detecting circuit 10 can convert the capacitance value of the sensing capacitor Cs into the output signal Vo.
  • the output signal Vo can be output to the fingerprint determination module at the back end to determine that the position of the fingerprint detection circuit 10 corresponds to a Finger Ridge or a Finger Valley.
  • FIG. 2 is an equivalent circuit diagram of the fingerprint detecting circuit 10.
  • the inverting amplifier 104 includes a first transistor Q1 and a second transistor Q2.
  • the first transistor Q1 is a P-type Metal Oxide Semiconductor Field Effect Transistor (PMOS FET)
  • the second transistor Q2 is an N-type transistor.
  • the gate of the first transistor Q1 is coupled to the gate of the second transistor Q2 to form an input terminal of the inverting amplifier 104 for receiving the input signal Vi, and the drain of the first transistor Q1 is coupled to The input terminal of the inverting amplifier 104 is formed by the drain of the second transistor Q2 for outputting an output signal Vo.
  • the source of the first transistor Q1 is used to receive the voltage VDD, and the source of the first transistor Q2 is used for Receive voltage VSS.
  • the circuit structure of the inverting amplifier 104 is the same as that of a complementary metal oxide semiconductor inverter (CMOS Inverter) applied to a digital circuit, and a general digital complementary MOS inverter.
  • CMOS Inverter complementary metal oxide semiconductor inverter
  • the fingerprint detecting circuit 10 couples the output end of the inverting amplifier 104 to the input terminal through the switching unit SW. When the switching unit SW is turned on, the output signal Vo is equal to the input signal Vi to ensure that the inverting amplifier 104 operates. In the linear amplification area.
  • FIG. 4 it is a schematic diagram of the input-output voltage conversion characteristics of the inverting amplifier 104.
  • the input signal Vi is greater than the voltage Vtp or less than the voltage Vtn, it is the saturation region Sat of the inverting amplifier 104, and when the input signal Vi is greater than the voltage VL and less than the voltage VH, the inverting amplifier 104 operates in the linear amplification region Ln.
  • the switching unit SW is controlled and turned on
  • the input signal Vi of the inverting amplifier 104 is equal to the output signal Vo
  • the inverting amplifier 104 is located at the DC operating point OP, that is, the inverting amplifier 104 operates in linear amplification.
  • the region Ln, and the inverting amplifier 104 has a negative gain, that is, the output signal Vo is decremented (incremented) as the input signal Vi increases (decreases).
  • the fingerprint detecting circuit 10 can accurately convert the capacitance value of the sensing capacitor Cs into the output signal Vo by using only the inverting amplifier 104 having a simple circuit configuration in combination with the switching unit SW. Compared with the prior art, the fingerprint detecting circuit 10 does not require an additional bias circuit, and the circuit structure is simple and accurate.
  • the first transistor Q1 and the second transistor Q2 are not limited to a metal oxide half field effect transistor (MOSFET), and may be a high-electron electron mobility transistor (HEMT). It belongs to the scope of the invention.
  • the inverting amplifier is not limited to the circuit structure shown in FIG. 3, any inverter originally used in a digital circuit (ie, an inverting circuit having a negative gain and a single-ended input single-ended output), as long as the coupling is coupled. It is within the scope of the invention to connect the switching unit between the input and output of the inverter to limit the operation of the inverter to the linear amplification region.
  • the fingerprint detecting circuit 10 can be applied to the fingerprint identification system.
  • FIG. 5 it is a schematic diagram of the fingerprint identification system 50 according to the second embodiment of the present invention.
  • the fingerprint identification system 50 includes the fingerprint determination module 500 and the fingerprint detection circuits 10_1 to 10_M.
  • the circuit structure of the fingerprint detection circuits 10_1 to 10_M is the same as that of the fingerprint detection circuit 10, and details are not described herein.
  • the fingerprint detection circuits 10_1 to 10_M are coupled to the fingerprint determination module 500, and output the generated output signals Vo_1 to Vo_M to the fingerprint determination module 500.
  • the fingerprint determination module 500 can determine the fingerprint detection circuits 10_1 to 10_M according to the output signals Vo_1 to Vo_M. The position corresponds to the bee or grain. It should be noted that the areas of the conductive layers 100 and 102 in the fingerprint detecting circuits 10_1 to 10_M are all fixed areas, and the capacitance values of the reference capacitors Cf are fixed capacitance values. Therefore, the relative values between the output signals Vo_1 to Vo_M can be utilized.
  • the voltage value determines the relative capacitance value of the capacitance value of the sensing capacitor Cs in the fingerprint detecting circuits 10_1 to 10_M, and it can be determined that the positions of the fingerprint detecting circuits 10_1 to 10_M correspond to the bees or grains.
  • the fingerprint detecting circuit of the embodiment of the present invention utilizes a single-ended input single-ended output inverting amplifier, and uses the switching unit to quickly and correctly establish a DC bias operating point of the inverting amplifier, and the sensing capacitor The capacitance value is accurately converted into an output signal.
  • the fingerprint detecting circuit of the embodiment of the present invention does not need to configure an additional bias circuit, and the circuit structure is simple and accurate.

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Computer Vision & Pattern Recognition (AREA)
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Abstract

本发明适用于指纹检测技术领域，提供了一种指纹检测电路，包含有：第一导电层；第二导电层；反相放大器，包含有：仅一输入端，耦接于所述第一导电层；以及输出端，耦接于所述第二导电层；以及开关单元，用于建立所述反相放大器的直流工作点，所述开关单元的一端耦接于所述反相放大器的输入端，所述开关单元的另一端耦接于所述反相放大器的输出端。本发明利用单端输入单端输出的反相放大器，并利用开关单元快速地且正确地建立该反相放大器的直流偏压工作点，将感测电容的电容值准确地转换成输出信号，毋须配置额外的偏压电路，其电路结构简单且准确度高。

Description

指纹检测电路及指纹辨识系统 技术领域
本发明属于指纹检测技术领域，涉及一种指纹检测电路及指纹辨识系统，尤其涉及一种准确度高且电路结构简单的指纹检测电路及指纹辨识系统。
背景技术
随着科技日新月异，移动电话、数字相机、平板电脑和笔记本电脑等越来越多的便携式电子装置已经成为了人们生活中必备的工具。由于便携式电子装置一般为个人使用，具有一定的隐私性，其内部储存的数据，例如电话簿、相片、个人信息等等为私人所有。若电子装置一旦丢失，这些数据可能会被他人所利用，造成不必要的损失。虽然目前已有利用密码保护的方式来避免电子装置为他人所使用，但密码容易泄露或遭到破解，具有较低的安全性。并且用户需记住密码才能使用电子装置，若忘记密码，则会带给使用者许多不便。因此，目前发展出利用个人指纹辨识的方式来达到身份认证的目的，以提升数据安全性。
在现有技术中，电容式指纹辨识系统是相当受欢迎的一种指纹辨识方法，其是利用感测电容以判断使用者指纹的纹峰(Finger Ridge)或纹谷(Finger Valley)。详细来说，电容式指纹辨识系统利用金属电极来接收使用者的手指接触，电容式指纹辨识系统中的指纹检测电路可将金属电极与使用者手指之间的电容转换成电压信号，并输出至后端的指纹判断模块，以进行指纹识别。然而，电容式指纹辨识系统中的指纹检测电路通常需要复杂的偏压电路，以确保指纹检测电路可正确地运作(即指纹检测电路之直流偏压工作点位于适当的区域)，而过于简单的偏压电路会影响指纹检测电路的准确度。因此，如何提供准确度高且电路结构简单的指纹检测电路也就成为业界所努力的目标之一。
发明内容
本发明的目的在于提供一种指纹检测电路及指纹辨识系统，旨在提高指纹检测的准确度高，且电路结构简单。
本发明是这样实现的，一种指纹检测电路，包含有：
第一导电层；
第二导电层；
反相放大器，包含有：仅一输入端，耦接于所述第一导电层；以及输出端，耦接于所述第二导电层；以及
开关单元，用于建立所述反相放大器的直流工作点，所述开关单元的一端耦接于所述反相放大器的输入端，所述开关单元的另一端耦接于所述反相放大器的输出端。
本发明的目的还在于提供一种指纹辨识系统，包含有：
多个指纹检测电路，每一指纹检测电路包含有：
第一导电层；
第二导电层；
反相放大器，包含有：仅一输入端，耦接于所述第一导电层；以及输出端，耦接于所述第二导电层；以及
开关单元，用于建立所述反相放大器的直流工作点，所述开关单元的一端耦接于所述反相放大器的输入端，所述开关单元的另一端耦接于所述反相放大器的输出端；
指纹判断模块，耦接于所述多个指纹检测电路，用来判断每一指纹检测电路对应至纹峰(Finger Ridge)或纹谷(Finger Valley)。
本发明实施例利用单端输入单端输出的反相放大器，并利用开关单元快速地且正确地建立该反相放大器的直流偏压工作点，将感测电容的电容值准确地转换成输出信号，毋须配置额外的偏压电路，其电路结构简单且准确度高。
附图说明
图1是本发明实施例一提供的指纹检测电路的示意图；
图2是图1中指纹检测电路的等效电路图；
图3是图1中反相放大器的示意图；
图4是图3中反相放大器的电压转换特性示意图；
图5是本发明实施例二提供的指纹辨识系统的示意图。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
如图1所示，为本发明实施例一指纹检测电路10的示意图。指纹检测电路10包含反相放大器104、开关单元SW和导电层100、102。导电层100为顶层导电层，其可为金属电极或是集成电路布局的金属层(Metal)，用于接收手指FG的接触。导电层102为下层导电层，其可为金属电极、金属层或集成电路布局的多晶硅层(Poly)。导电层102设置于导电层100下方，导电层100与导电层102之间形成参考电容Cf，而导电层100与手指FG形成有感测电容Cs。反相放大器104为单端输入单端输出(Single Input Single Output)放大器，其包含单一输入端及输出端，反相放大器104的输入端耦接于导电层100，输出端耦接于导电层102。开关单元SW用于建立反相放大器104的直流偏压，开关单元SW的一端耦接于反相放大器104的输入端，开关单元SW的另一端耦接于反相放大器104的输出端。
详细来说，参考电容Cf的电容值取决于导电层102的面积，当导电层100、102的面积为固定面积时，参考电容Cf的电容值为固定电容值。另外，感测电容Cs的电容值会随手指FG的指纹特征而变化。除此之外，手指FG可透过金 属电极接收驱动信号Vs，驱动信号Vs可透过感测电容Cs耦合至反相放大器104的输入端，即驱动信号Vs通过感测电容Cs后，于反相放大器104的输入端形成输入信号Vi，反相放大器104接收输入信号Vi后产生输出信号Vo，如此一来，指纹检测电路10可将感测电容Cs的电容值转换成输出信号Vo。输出信号Vo可输出至后端的指纹判断模块，以判断指纹检测电路10所在位置对应至手指的纹峰(Finger Ridge)或纹谷(Finger Valley)。
详细来说，请继续参考图2，为指纹检测电路10的等效电路图。由图2可知，驱动信号Vs与感测电容Cs的关系式可表示为CsVs＝－CfVo，因此，指纹判断模块可根据输出信号Vo推算出感测电容Cs的电容值为Cs＝－(Cf/Vs)*Vo，并判断指纹检测电路10对应至纹峰或纹谷。
另一方面，反相放大器104的实现方式可视实际需求而调整，举例来说，如图3所示，为反相放大器104的示意图。反相放大器104包含第一晶体管Q1和第二晶体管Q2，第一晶体管Q1为P型金氧半场效晶体管(P-type Metal Oxide Semiconductor Field Effect Transistor，PMOS FET)，第二晶体管Q2为N型金氧半场效晶体管(NMOS FET)。第一晶体管Q1的栅极(Gate)耦接至第二晶体管Q2的栅极而形成反相放大器104的输入端，用于接收输入信号Vi，第一晶体管Q1的漏极(Drain)耦接至第二晶体管Q2的漏极而形成反相放大器104的输入端，用于输出一输出信号Vo，第一晶体管Q1的源极(Source)用于接收电压VDD，第一晶体管Q2的源极用于接收电压VSS。
由图3可知，反相放大器104的电路结构相同于应用于数字电路中的互补式金氧半反相器(Complementary Metal Oxide Semiconductor Inverter，CMOS Inverter)，与一般数字互补式金氧半反相器不同的是，反相放大器104的直流偏压工作点位于线性放大区而非饱和区(一般数字互补式金氧半反向器的直流偏压工作点位于反相器电路的饱和区)。具体来说，指纹检测电路10透过开关单元SW将反相放大器104的输出端耦接至输入端，当开关单元SW导通时，输出信号Vo等于输入信号Vi，以确保反相放大器104工作于线性放大区。
详细来说，如图4所示，为反相放大器104的输入输出电压转换特性示意图。当输入信号Vi大于电压Vtp或小于电压Vtn时，即为反相放大器104的饱和区Sat，而当输入信号Vi大于电压VL且小于电压VH时，反相放大器104工作于线性放大区Ln。具体来说，当开关单元SW受控而导通时，反相放大器104的输入信号Vi与输出信号Vo相等，此时反相放大器104位于直流工作点OP，即反相放大器104工作于线性放大区Ln，且反相放大器104具有负向增益，即输出信号Vo随输入信号Vi增加(减少)而递减(递增)。
由上述可知，指纹检测电路10仅利用电路结构简单的反相放大器104搭配开关单元SW，即可将感测电容Cs的电容值准确地转换成输出信号Vo。相较于现有技术，指纹检测电路10不需要额外的偏压电路，其电路结构简单且准确度高。
需注意的是，前述实施例是用以说明本发明的概念，本领域具通常知识者当可据以做不同之修饰，而不限于此。举例来说，于反相放大器104中，第一晶体管Q1及第二晶体管Q2不限于为金氧半场效晶体管(MOSFET)，亦可为高速电子移动晶体管(High Electron Mobility Transistor，HEMT)，亦属于本发明的范畴。另外，反相放大器不限于为图3所示的电路结构，任何原本应用于数字电路中的反相器(即具有负向增益且为单端输入单端输出的反相电路)，只要搭配耦接于该反相器的输入端与输出端之间的开关单元以限制该反相器工作于线性放大区，皆属于本发明之范畴。
除此之外，指纹检测电路10可应用于指纹辨识系统，如图5所示，为本发明实施例二的指纹辨识系统50的示意图。指纹辨识系统50包含有指纹判断模块500和指纹检测电路10_1～10_M，指纹检测电路10_1～10_M的电路结构与指纹检测电路10相同，在此不再赘述。
指纹检测电路10_1～10_M耦接于指纹判断模块500，将其产生的输出信号Vo_1～Vo_M输出至指纹判断模块500，指纹判断模块500即可根据输出信号Vo_1～Vo_M判断指纹检测电路10_1～10_M所在位置对应至纹蜂或纹谷。 需要注意的是，指纹检测电路10_1～10_M中导电层100、102的面积皆为固定面积，其参考电容Cf的电容值皆为固定电容值，因此，可利用输出信号Vo_1～Vo_M之间的相对电压值判断指纹检测电路10_1～10_M中感测电容Cs电容值的相对电容值，即可判断指纹检测电路10_1～10_M所在位置对应至纹蜂或纹谷。
综上所述，本发明实施例的指纹检测电路利用单端输入单端输出的反相放大器，并利用开关单元快速地且正确地建立该反相放大器的直流偏压工作点，将感测电容的电容值准确地转换成输出信号。相较于现有技术，本发明实施例的指纹检测电路毋须配置额外的偏压电路，其电路结构简单且准确度高。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种指纹检测电路，其特征在于，包含有：
    第一导电层；
    第二导电层；
    反相放大器，包含有：仅一输入端，耦接于所述第一导电层；以及输出端，耦接于所述第二导电层；以及
    开关单元，用于建立所述反相放大器的直流工作点，所述开关单元的一端耦接于所述反相放大器的输入端，所述开关单元的另一端耦接于所述反相放大器的输出端。
  2. 如权利要求1所述的指纹检测电路，其特征在于，所述第二导电层位于所述第一导电层下方，所述第二导电层与所述第一导电层之间形成参考电容，所述参考电容的电容值相关于所述第二导电层的面积。
  3. 如权利要求1所述的指纹检测电路，其特征在于，所述反相放大器具有负向增益。
  4. 如权利要求1所述的指纹检测电路，其特征在于，所述反相放大器包含有：
    第一晶体管，包含有第一端、第二端和第三端；以及
    第二晶体管，包含有：
    第一端，耦接至所述第一晶体管的第一端；
    第二端，耦接至所述第一晶体管的第二端；以及
    第三端；
    其中，所述第一晶体管的第三端用来接收第一电压，所述第二晶体管的第三端用于接收第二电压；
    其中，当所述开关单元导通时，所述反相放大器的所述直流工作点位于放大区。
  5. 如权利要求4所述的指纹检测电路，其特征在于，所述第一晶体管及所述第二晶体管其中之一为P型晶体管，另一晶体管为N型晶体管。
  6. 一种指纹辨识系统，用于进行指纹辨识，包含有：
    多个指纹检测电路，每一指纹检测电路包含有：
    第一导电层；
    第二导电层；
    反相放大器，包含有：仅一输入端，耦接于所述第一导电层；以及输出端，耦接于所述第二导电层；以及
    开关单元，用于建立所述反相放大器的直流工作点，所述开关单元的一端耦接于所述反相放大器的输入端，所述开关单元的另一端耦接于所述反相放大器的输出端；
    指纹判断模块，耦接于所述多个指纹检测电路，用来判断每一指纹检测电路对应至纹峰(Finger Ridge)或纹谷(Finger Valley)。
  7. 如权利要求6所述的指纹辨识系统，其特征在于，所述第二导电层位于所述第一导电层下方，所述第二导电层与所述第一导电层之间形成参考电容，所述参考电容的电容值相关于所述第二导电层的面积。
  8. 如权利要求6所述的指纹辨识系统，其特征在于，所述反相放大器具有负向增益。
  9. 如权利要求6所述的指纹辨识系统，其特征在于，所述反相放大器包含有：
    第一晶体管，包含有第一端、第二端和第三端；以及
    第二晶体管，包含有：
    第一端，耦接至所述第一晶体管的第一端；
    第二端，耦接至所述第一晶体管的第二端；以及
    第三端；
    其中，所述第一晶体管的第三端用来接收第一电压，所述第二晶体管的第三端用于接收第二电压；
    其中，当所述开关单元导通时，所述反相放大器的直流工作点位于放大区。
  10. 如权利要求9所述的指纹辨识系统，其特征在于，所述第一晶体管及所述第二晶体管其中之一为P型晶体管，另一晶体管为N型晶体管。
PCT/CN2015/094638 2015-07-27 2015-11-16 指纹检测电路及指纹辨识系统 Ceased WO2017016102A1 (zh)

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