CN107066960A - A kind of signal processing circuit for fingerprint sensor - Google Patents
A kind of signal processing circuit for fingerprint sensor Download PDFInfo
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- CN107066960A CN107066960A CN201710209368.2A CN201710209368A CN107066960A CN 107066960 A CN107066960 A CN 107066960A CN 201710209368 A CN201710209368 A CN 201710209368A CN 107066960 A CN107066960 A CN 107066960A
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Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR 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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/20—Indexing scheme relating to power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F2203/21—Indexing scheme relating to power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F2203/211—Indexing scheme relating to power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only using a combination of several amplifiers
- H03F2203/21136—An input signal of a power amplifier being on/off switched
Abstract
The invention discloses a kind of signal processing circuit for fingerprint sensor, including：First input circuit, the second input circuit and difference amplifier；First input circuit is used to be electrically connected with the first fingerprint sensing module, and the first sensing signal that the first fingerprint sensing module is generated is supplied to difference amplifier；Second input circuit is used to be electrically connected with the second fingerprint sensing module, and the second sensing signal is supplied into difference amplifier；The difference amplifier includes first input end and the second input, and the first signal processing unit being electrically connected with the first input end, the secondary signal processing unit being electrically connected with second input；First signal processing unit and the secondary signal processing unit are coupled, and first sensing signal and the second sensing signal are carried out into differential amplification processing, and the difference amplifier is also included the output end of the signal output after the processing.
Description
Technical field
The present invention relates to fingerprint sensing technical field, more particularly to a kind of signal processing circuit for fingerprint sensor.
Background technology
At present, fingerprint sensor is widely used in the client device with fingerprint identification function, the client
Equipment can for example include intelligent movable phone, computer (including notebook computer, desktop computer), Flat electronic equipment, individual
Personal digital assistant (PDA) or intelligent wearable device etc..
Fig. 1 is the application schematic diagram of capacitive fingerprint sensing device in the prior art, as shown in figure 1, finger and fingerprint sensing
During the touch insulating barrier contact of device, coupled capacitor C is formed between finger and touch insulating barrierfinger, due to finger fingerprint ridge and
The distance of fingerprint valley to the touch insulating barrier is different, therefore, is formed between finger various pieces and the touch insulating barrier
Coupling capacitance is also differed.In order to recognize the finger print information of each part of finger, the touch insulating barrier is generally divided into one
Each and every one unit, the unit constitutes fingerprint sensing cell array.The important function of fingerprint sensor is the collection fingerprint sensing
The coupling capacitance of each unit in cell array, and the finger print information according to corresponding to the capacitance identifies the unit.
Based on the application mode of above-mentioned capacitance sensor, traditional capacitive fingerprint sensing device is introduced below by Fig. 2
The signal processing mode of (charge transfer) is changed based on electric charge.As shown in Fig. 2 (i.e. being opened in clock PH1 phases in Fig. 2
PH1 conductings, switch PH2 is closed to disconnect), fingerprint sensor is in reset mode.(i.e. switch PH2 in Fig. 2 to lead in clock PH2 phases
Logical, switch PH1 disconnects), fingerprint sensor is in sampling mode, and voltage signal Vcharge is used to weaken or eliminate in Fig. 1 to touch
Touch the fixed imbalance produced by the parasitic capacitance Cs between insulating barrier and conductive layer.In order to strengthen difference amplifier AMP1 inputs
Capacitive load, can voltage signal Vcharge and AMP1 reverse input end access electric capacity C0, still, due to coupling electricity
Hold CfingerValue do not fix, cause Vcharge and electric capacity C0 value to be difficult to set, and then cause voltage signal Vcharge simultaneously
The fixed imbalance that parasitic capacitance Cs is brought can not be completely eliminated.In addition, in clock PH2 phases, some frequency ranges power supply or
Noise in the presence of difference amplifier AMP1, is transferred to AMP1's by the influence of noise produced on the ground to reference voltage V ref
On output voltage Vo1, and then influence sampling coupled capacitor CfingerElectric charge conversion between reference capacitance Cref, causes fingerprint
Poor quality images.Power supply or the noise of ground are generally to touch in common-mode noise, similar Fig. 1 and posted between insulating barrier and conductive layer
Raw electric capacity Cs influence, but parasitic capacitance Cs is fixed value, and the common-mode noise of power supply or ground has randomness.In order to keep away
The influence that the common-mode noise of power-free or ground is caused to fingerprint Identification sensor, proposes a kind of improved fingerprint sensor
Signal processing unit is particularly important.Fig. 3 is the signal processing circuit in the prior art based on the improved fingerprint sensors of Fig. 2
Structure chart.As shown in figure 3, improvements of the Fig. 3 relative to Fig. 2 is to connect difference amplifier AMP2 reverse input ends in Fig. 2
Common-mode voltage Vcom be substituted for fixed reference input circuit, the reference input circuit have and Fig. 2 shown in fingerprint it is defeated
Enter circuit identical structure.Specifically in the course of the work, likewise it is possible to control fingerprint sensor by switching PH1 and PH2
Reset mode or sampling mode.In the circuit structure shown in Fig. 3, although reference voltage V ref or other connection power supplys or
The circuit module on person ground still carries common-mode noise, and passes through difference amplifier AMP3 and AMP4 enhanced processing, but the
Be present identical common-mode noise in one input circuit and the second input circuit, suppress by difference amplifier AMP5 common-mode signal
Afterwards, it can weaken or even eliminate influence of the common-mode noise to output result.But above-mentioned decrease or elimination common-mode noise shadow
Ring and be based only on the scene that the fingerprint sensing module connected with fingerprint input circuit has finger to contact.If fingerprint input circuit does not have
Finger is contacted or finger is insufficient contact, then common mold noise interference can not be transferred to difference by charge transfer structures
Divide amplifier AMP5 input, after AMP5 difference processing, common-mode noise can not still be eliminated or even weakened,
Its effect is similar with traditional signal processing mode shown in Fig. 2.
Therefore, a kind of signal processing circuit for the fingerprint sensor that can eliminate common-mode noise is needed badly in the prior art.
The content of the invention
, can it is an object of the invention to provide the signal processing circuit that a kind of circuit structure is simply to fingerprint sensor
Effectively eliminate the influence of common-mode noise.
The above-mentioned purpose of the present invention can be realized using following technical proposal：
A kind of signal processing circuit for fingerprint sensor, including：First input circuit, the second input circuit and difference
Amplifier；
First input circuit is used to be electrically connected with the first fingerprint sensing module of the fingerprint sensor, by institute
The first sensing signal for stating the generation of the first fingerprint sensing module is supplied to the difference amplifier；
Second input circuit is used to be electrically connected with the second fingerprint sensing module of the fingerprint sensor, by institute
The second sensing signal for stating the generation of the second fingerprint sensing module is supplied to the difference amplifier；First fingerprint sensing module
The sensing different with any two in the fingerprint sensing module array that second fingerprint sensing module is the fingerprint sensor
Module；
The difference amplifier include opposite polarity and respectively with first input circuit and second input circuit
The first input end of electric connection and the second input, and the first signal transacting list being electrically connected with the first input end
Member, the secondary signal processing unit being electrically connected with second input；First signal processing unit and described second
Signal processing unit is coupled, and first sensing signal and the second sensing signal are carried out into differential amplification processing, the difference
Amplifier is divided also to include the output end of the signal output after the processing.
Further, first signal processing unit, the secondary signal processing unit have row selecting switch, column selection
Switch is selected, when first signal processing unit, the row selecting switch of the secondary signal processing unit, column select switch quilt
During conducting, first signal processing unit and the secondary signal processing unit coupling generation difference amplifier.
Further, the row selecting switch, the column select switch are switched on or off by Digital Circuit Control.
Further, it is used to amplify described first in first signal processing unit, the secondary signal processing unit
The area of the input transistors of sensing signal and the second sensing signal is not less than the first predetermined threshold value.
Further, in the difference amplifier, first signal processing unit and secondary signal processing are single
The shared tail current source of member and output loading.
Further, there is common mode feedback loop in first signal processing unit, the secondary signal processing unit,
The common mode feedback loop is used to control the tail current source, to stablize the common mode operation voltage of the difference amplifier.
Further, the first output end that the output end includes being used to export the first output voltage is exported with output second
Second output end of voltage, first output signal is used to determine the corresponding finger print information of first fingerprint sensing module,
Second output signal is used to determine the corresponding finger print information of second sensing module.
Further, the signal processing circuit also includes：
First control module, reset function is worked in for starting the fingerprint sensor；
Second control module, sampled functions are worked in for starting the fingerprint sensor.
Further, first fingerprint sensing module, second fingerprint sensing module also include touching for interconnection
Insulating barrier and conductive layer are touched, the conductive layer is connected with the first input end, the second input；When the fingerprint sensor quilt
When being set to sampling mode, finger or the conductive layer are applied in the voltage of default value, and finger, which is touched, described touches insulation
During layer, coupled capacitor is produced between finger and the conductive layer；First fingerprint sensing module, the second fingerprint sensing mould
First sensing signal that the voltage generation that block is based respectively on the application matches with the coupling capacitance and described the
Two sensing signals.
Further, when the fingerprint sensor is arranged to reset mode, in the first input end and described
Two inputs apply fixed voltage, to adjust the circuit operating point of the difference amplifier.
Further, first control module includes：
Two feedback capacities, one end of the feedback capacity is connected to the first input end, the second input, separately
One end is connected with the output end respectively；
Two the first reset switches, first reset switch is connected to the two ends of the feedback capacity；
Two the second reset switches, one end of second reset switch is connected with each other, and the other end is respectively with described first
Input, the connection of the second input；
Two the 3rd reset switches, one end of the 3rd reset switch respectively with first fingerprint sensing module,
Two fingerprint sensing modules are connected, and the other end is grounded respectively；
First reset switch, the second reset switch, the 3rd reset switch be switched on or off it is consistent.
Further, second control module includes：
Two sampling switches, one end of the sampling switch respectively with first fingerprint sensing module, the second fingerprint sense
Module connection is surveyed, the other end is connected with first output end, the second input respectively.
Further, first input circuit includes first adder, and the first adder is respectively with described first
Fingerprint sensing module and the adjacent fingerprint sensing module of first fingerprint sensing module are electrically connected with, for described first
Sensing signal and the sensing signal of the adjacent fingerprint sensing module generation of first fingerprint sensing module carry out read group total,
The summation sensing signal of generation first；
Accordingly, second input circuit includes second adder, and the second adder refers to described second respectively
Line sensing module and the adjacent fingerprint sensing module of second fingerprint sensing module are electrically connected with, for feeling to described second
The sensing signal for surveying signal and the adjacent fingerprint sensing module generation of second fingerprint sensing module carries out read group total, raw
Into the second summation sensing signal；
Correspondingly, first signal processing unit and the secondary signal processing unit are coupled, by described first
Summation sensing signal and the second summation sensing signal carry out differential amplification processing.A kind of fingerprint sensor, the fingerprint sensor
Including the signal processing circuit described in any one in claim 1-12, wherein, the quantity of the fingerprint sensing module and institute
The quantity for stating signal processing unit matches.
Further, the fingerprint sensor includes the tail current source of predetermined number, output loading, the predetermined number
Less than the quantity of the signal processing unit.
A kind of electronic equipment, the electronic equipment includes fingerprint sensor, and the fingerprint sensor includes claim
Signal processing circuit in 1-12 described in any one.
Further, there is the function of quick charge in the electronic equipment.
Further, the electronic equipment include it is following in any one：Intelligent movable phone, notebook computer, platform
Formula computer, Flat electronic equipment, personal digital assistant (PDA), intelligent wearable device.
The signal processing circuit for fingerprint sensor that the application is provided, it is possible to use at the signal in fingerprint sensor
Unit is managed, arbitrary two signal processing units difference amplifier is coupled into, the difference amplifier has certain gain,
Faint sensing signal can be amplified, can also weaken or eliminate the common-mode noise that power supply or ground are brought in circuit.
For capacitance type sensor, it can also weaken or eliminate touching the mistake that the parasitic capacitance Cs between insulating barrier and conductive layer is brought
Adjust influence.In addition, relative to signal processing circuit structure of the prior art, be connected to differential amplifier inputs two are defeated
Enter circuit and be connected to fingerprint sensing module, whether finger contacts or fully contact the finger contact surface to difference amplifier
Common-mode noise or imbalance etc. are eliminated without large effect.
Brief description of the drawings
Fig. 1 is the application schematic diagram of capacitive fingerprint sensing device in the prior art；
Fig. 2 is the signal processing circuit structure schematic diagram changed based on electric charge of traditional capacitive fingerprint sensing device；
Fig. 3 is the signal processing circuit structure schematic diagram in the prior art based on the improved fingerprint sensors of Fig. 2；
Fig. 4 is the modular structure schematic diagram for the signal processing circuit that the application is provided；
Fig. 5 is a kind of electrical block diagram for the signal processing circuit that the application is provided；
Fig. 6 is electrical block diagram of Fig. 5 fingerprint sensor in PH2 phases；
Fig. 7 is electrical block diagram of the fingerprint sensor shown in Fig. 5 in PH1 phases；
Fig. 8 is another electrical block diagram for the signal processing circuit that the application is provided；
Fig. 9 is the electrical block diagram for the signal processing unit that the application is provided；
Figure 10 is the structural representation of the one embodiment for the difference amplifier that the application is provided；
Figure 11 is another electrical block diagram for the signal processing circuit that the application is provided.
Embodiment
Below in conjunction with the drawings and specific embodiments, technical scheme is elaborated, it should be understood that these
Embodiment is only illustrative of the invention and is not intended to limit the scope of the invention, after the present invention has been read, this area skill
Modification of the art personnel to the various equivalent form of values of the present invention is each fallen within the application appended claims limited range.
The technological accumulation and inheritance of technical scheme is described below, at present, the client device such as many smart mobile phones can be propped up
Hold high voltage and/or large current charge pattern, an advantage of high voltage and/or large current charge pattern is to realize fast
Speed charging.When client device is charged using high voltage and/or large current charge pattern, the power supply of charger or ground
Noise easily disturb the power supply and ground of client device, so as to have influence on the normal operating conditions of fingerprint sensor.At one
In typical application environment, the charger of user mobile phone is high-voltage charge pattern, also with fingerprint sensor, is entered to mobile phone
During row charging, when user carries out the operation such as mobile phone interface unblock, payment using fingerprint, mobile phone None- identified fingerprint is found, is led
Apply family can not complete mobile phone interface unblock, pay etc. operation.
Based on above-mentioned technological accumulation and inheritance, the signal processing circuit for fingerprint sensor that the application is provided can with
The client device of fingerprint sensor is removed due to high voltage and/or high current when carrying out high voltage and/or large current charge
Noise jamming caused by charging so that client device can also enter when high voltage and/or large current charge is carried out
Row fingerprint recognition, it is ensured that the normal of client device fingerprint identification function is used.
Below referring to Fig. 4, the specific technical scheme for introducing the application.As shown in figure 4, being provided in the application embodiment
The signal processing circuit for fingerprint sensor can include：First input circuit 402, the second input circuit 404 and difference
Amplifier 405.
First input circuit 402 is used to be electrically connected with the first fingerprint sensing module 401 of the fingerprint sensor,
The difference amplifier 405 is supplied to the first sensing signal for generating first fingerprint sensing module 401.
Second input circuit 404 is used to be electrically connected with the second fingerprint sensing module 403 of the fingerprint sensor,
The difference amplifier 405 is supplied to the second sensing signal for generating second fingerprint sensing module 403；Described first
Fingerprint sensing module 401 and the fingerprint sensing module array 408 that second fingerprint sensing module 403 is the fingerprint sensor
The different sensing module of middle any two.
The difference amplifier 405 include opposite polarity and respectively with first input circuit 402 and described second defeated
Enter the first input end and the second input of the electric connection of circuit 404, and first be electrically connected with the first input end
Signal processing unit 406, the secondary signal processing unit 407 being electrically connected with second input；At first signal
Reason unit 406 and the secondary signal processing unit 407 are coupled, and first sensing signal and the second sensing signal are entered
Row differential amplification processing, the difference amplifier 405 is also included the output end of the signal output after the processing.
In the present embodiment, the fingerprint sensing module array 408 can include multiple sensing modules, such as described fingerprint sense
The sensing module of a variety of quantity specifications such as 64 × 64,128 × 128,50 × 50,120 × 60 can be included by surveying module array.At this
In one embodiment of application, the sensing module can have finger contact surface, and the finger contact surface can for example include
Touch insulating barrier shown in Fig. 1.When finger contacts the finger contact surface, one is produced between finger and the finger contact surface
Fixed physical quantity variation.If for example, when the fingerprint sensor is capacitance type sensor, finger touches the finger contact surface
When, the change of coupled capacitor is produced between finger and the finger contact surface.If the fingerprint sensor is optical sensor,
The change of bright and dark light is produced between finger and the finger contact surface.Based on this, the sensing module can be used for gathering institute
Physical quantity variation is stated, and the physical quantity variation is changed into sensing signal, the sensing signal can for example include being easy to place
The voltage signal of reason.And first fingerprint sensing module 401 and second fingerprint sensing module 403 in the application are institute
State the different sensing module of any two in the fingerprint sensing module array 408 of fingerprint sensor.
First input circuit 402 and second input circuit 404 in the present embodiment have the work that signal is transmitted
With, one end is electrically connected with first fingerprint sensing module 401, the second fingerprint sensing module 403 respectively, the other end respectively with
Positive input and the reverse input end connection of difference amplifier 405.Specifically for what the first fingerprint sensing module 401 was generated
First sensing signal, the second sensing signal of the second fingerprint sensing module 403 generation are supplied to the difference amplifier 405.
Signal processing unit in the present embodiment can have with the sensing module in the fingerprint sensing module array 408
One-to-one relation, first signal processing unit 406, secondary signal processing unit 407 can correspond respectively to described
First fingerprint sensing module 401 and second fingerprint sensing module 403.First signal processing unit 406 and described
Binary signal processing unit 407 can be coupled into the difference amplifier 405.The difference amplifier 405 is used for described first
Sensing signal and second sensing signal carry out differential amplification processing, and export the signal after the processing.Specifically, institute
Difference amplifier 405 is stated with certain gain, faint sensing signal can be amplified, in addition, relative to shown in Fig. 3
Difference amplifier single ended input structure, first input circuit 402 and second input circuit in the present embodiment
404 access the positive and negative two ends of the difference amplifier 405 simultaneously, form the structure of double-width grinding, for capacitance type sensor,
It can not only weaken or eliminate and touch the offset influence that the parasitic capacitance Cs between insulating barrier and conductive layer is brought, can also subtract
The common-mode noise that power supply or ground are brought in weak or elimination circuit.Meanwhile, first input circuit 402 and second input
Circuit 404 is the input circuit for connecting fingerprint sensing module, and whether finger contacts or fully contact the finger contact surface
Common-mode noise or imbalance etc. are eliminated to difference amplifier 405 without large effect.
The signal processing circuit for fingerprint sensor that the application is provided, it is possible to use at the signal in fingerprint sensor
Unit is managed, arbitrary two signal processing units difference amplifier is coupled into, the difference amplifier has certain gain,
Faint sensing signal can be amplified, can also weaken or eliminate the common-mode noise that power supply or ground are brought in circuit.
For capacitance type sensor, it can also weaken or eliminate touching the mistake that the parasitic capacitance Cs between insulating barrier and conductive layer is brought
Adjust influence.In addition, relative to signal processing circuit structure of the prior art, be connected to differential amplifier inputs two are defeated
Enter circuit and be connected to fingerprint sensing module, whether finger contacts or fully contact the finger contact surface to difference amplifier
Common-mode noise or imbalance etc. are eliminated without large effect.
In a specific example, in order to clearly show the details of this programme, therefore fingerprint is passed without limitation
Sensor is configured to capacitive fingerprint sensing device, still, one of skill in the art will understand that, the fingerprint sensor of this programme can
With the sensor of any induction mode.Process description the application offer is moved towards below by the signal of capacitive fingerprint sensing device
Signal processing circuit.
One fingerprint sensor has the fingerprint sensing module array being made up of 64 × 64 fingerprint sensing modules, wherein each
Fingerprint sensing module has the finger contact surface for user's finger contacts.When finger touch the finger contact surface when, finger with
The change of coupled capacitor is produced between the finger contact surface.The sensing module gathers the coupled capacitor, and by the coupling
Close electric capacity and be converted into easy-to-handle sensing signal, the sensing signal is such as can include voltage signal, current signal.
Accordingly, the fingerprint sensor has 64 × 64 signal processing units and 64 × 64 fingerprint sensing moulds
Block is corresponded, and the output data that each signal processing unit processes are obtained is corresponding fingerprint sensing module institute
The finger print information of collection.As described above, common-mode noise the fingerprint interference module can be disturbed by power supply or ground, it is described defeated
Enter circuit, described signal processing unit etc..In order to weaken or even remove the common-mode noise, due to each signal transacting
The structure of unit is identical, therefore any two in 64 × 64 signal processing units can be coupled into difference amplifier, institute
State difference amplifier not only can be amplified processing to faint sensing signal, can eliminate imbalance with suppression common mode noise
Influence.
In another specific example, the charger of user mobile phone is high-voltage charge pattern, also with fingerprint sensor,
As described in above technological accumulation and inheritance, when being charged to mobile phone, grasped when user carries out mobile phone interface unblock, payment etc. using fingerprint
When making, mobile phone None- identified fingerprint is found, causes user can not open mobile phone interface or be paid etc. using fingerprint.
Based on above-mentioned technological accumulation and inheritance, being installed on the signal processing circuit for fingerprint sensor in user mobile phone can be
When finger touches the button of mobile phone, fingerprint sensor in mobile phone is opened so that the fingerprint sensor starts to gather the finger of user
Line information.Mobile phone key correspond to the fingerprint sensing module finger contact surface, when finger touch mobile phone key when, finger with
Coupled capacitor is produced between sheet metal (i.e. conductive layer in Fig. 1) below mobile phone key, now, the signal processing circuit can
To gather the coupled capacitor, and the coupled capacitor is converted into pass in mobile phone after voltage signal or current signal
The difference amplifier in portion.The difference amplifier is coupled to form by any two signal processing unit, and the difference amplifier is not only
Processing can be amplified to faint sensing signal, offset influence can be eliminated with suppression common mode noise.
Therefore, when quick charge is carried out to mobile phone, the signal processing unit can also carry out fingerprint recognition, subtract
The weak accuracy that fingerprint recognition imaging is improved because of the influence of common-mode noise caused by quick charge, it is ensured that mobile fingerprint is recognized
The normal of function is used, thus further improve handset processes accuracy and user to the experience sense of mobile phone.
In one embodiment of the application, as shown in figure 4, the output end can include being used to export the first output electricity
Second output end of the second output voltage of the first output end and output of pressure, first output signal is determined for described
The corresponding finger print information of first fingerprint sensing module 401, second output signal is determined for the second fingerprint sense
Survey the corresponding finger print information of module 403.
The first output signal, the second output signal in the present embodiment are used directly for determining first fingerprint sensing
Module 401, the corresponding finger print information of the second fingerprint sensing module 403.For example, first output signal, the second output signal
When being magnitude of voltage, when first output signal is in the range of the first preset voltage value, first fingerprint sensing is determined
The finger print information of module 401 is fingerprint valley；When in the range of the second preset voltage value, first fingerprint sensing module is determined
401 finger print information is fingerprint ridge, and fingerprint can be imaged according to the finger print information.Specific first output signal,
The processing of second output signal can be realized in the data reading circuit shown in Fig. 4.For example, the data reading circuit can be with
Including programmable gain amplifier, analog-digital converter etc..Relative to the signal processing circuit of the prior art generation shown in Fig. 3
Vo1 and Vo2 can not be used for directly determining finger print information due to there is common mold noise interference, the signal transacting in the present embodiment
Structure only needs to one-level difference amplifier, you can amplifying sensing signal, weakening or even eliminating common-mode noise and imbalance.
As shown in Figure 4 in one embodiment of the application, the signal processing circuit can also include：
First control module, reset function is worked in for starting the fingerprint sensor；
Second control module, sampled functions are worked in for starting the fingerprint sensor.
In the present embodiment, the reset mode is mainly used in carrying out parameter replacement, the sampling to the fingerprint sensor
Pattern is mainly used in being acquired finger print information.Complete described by first control module and second control module
The switching of two kinds of mode of operations of fingerprint sensor.
In one embodiment of the application, Fig. 5 is a kind of knot of the embodiment for the signal processing circuit that the application is provided
Structure schematic diagram, as shown in figure 5, first control module can include：
Two feedback capacity Cref, the feedback capacity Cref are connected to the first input end and described first defeated
Go out between end, the second input and second output end；
Two first reset switches PH1-1, the first reset switch PH1-1 are connected to the feedback capacity Cref
Two ends；
Two second reset switches PH1-2, the second reset switch PH1-2 one end are connected with each other, other end difference
It is connected with the first input end, the second input；
Two the 3rd reset switch PH1-3, the 3rd reset switch PH1-3 one end respectively with the first fingerprint sense
Survey module 401, the second fingerprint sensing module 403 to connect, the other end is grounded respectively；
The first reset switch PH1-1, the second reset switch PH1-2, the 3rd reset switch PH1-3 conducting or disconnected
Open consistent.
In another embodiment of the application, second control module can include：
Two sampling switches PH2, the sampling switch PH2 one end respectively with first fingerprint sensing module 401,
Two fingerprint sensing modules 403 are connected, and the other end is connected with first output end, the second input respectively.
In the application, the sampling mode of the fingerprint sensor can be controlled by four groups of switches, wherein three groups of resets are opened
Close, respectively the first reset switch PH1-1, the second reset switch PH1-2, the 3rd reset switch PH1-3, one group of sampling switch
PH2.Wherein described first reset switch PH1-1, the second reset switch PH1-2, the 3rd reset switch PH1-3 can be by same controls
Signal control processed, to ensure the uniformity being switched on or off of this three groups of switches.When three groups of reset switch conductings, one group of sampling
When switching off, the fingerprint sensor is in reset mode, and the reset mode is mainly used in entering the fingerprint sensor
Row information is reset；On the contrary, when three groups of reset switches disconnect, during one group of sampling switch conducting, the fingerprint sensor is in and taken
Original mold formula, the sampling mode is mainly used in being acquired finger print information.
When finger touches the finger contact surface of the fingerprint sensing module, where fingerprint sensor or fingerprint sensor
Equipment can sense the contact of mobile phone, at this point it is possible to control four groups of switches by the clock signal of fixed frequency so that
The fingerprint sensor is switched in reset mode and sampling mode.
In one embodiment of the application, first fingerprint sensing module 401, second fingerprint sensing module
403 also include the touch insulating barrier and conductive layer of interconnection, and the conductive layer connects with the first input end, the second input
Connect；When the fingerprint sensor is in sampling mode, the sampling switch PH2 is turned on, first reset switch is disconnected
PH1-1, the second reset switch PH1-2, the 3rd reset switch PH1-3, finger are applied in the voltage of default value, and finger touches institute
When stating touch insulating barrier, coupled capacitor (referring to Fig. 1) is produced between finger and the conductive layer；First fingerprint sensing module
401st, second fingerprint sensing module 403 is based respectively on the voltage generation of the application and matched with the coupling capacitance
First sensing signal and second sensing signal.
In the present embodiment, first fingerprint sensing module 401, second fingerprint sensing module 403 also include mutual
The touch insulating barrier and conductive layer of connection.The insulation layers that touch are described to touch as that can include the touch insulating barrier shown in Fig. 1
Barium titanate, oxide, nitride, carbide, glass, ceramics, the sapphire in polyimide substrate can be included by touching insulating barrier
The type such as film dielectric material.Conductive layer conductive material such as can include metal level.Described in being touched when finger
When touching insulating barrier, coupled capacitor is formed between finger and the conductive layer.
Fig. 6 is the driving voltage in electrical block diagram of Fig. 5 fingerprint sensor in PH2 phases, Fig. 5
Vdriver can be the square-wave signal with fixed frequency, cycle of the square-wave signal and switching signal PH1-1, PH1-2,
PH1-3 and PH2 clock cycle is consistent.When switching signal PH1-1, PH1-2, PH1-3 conducting, PH2 disconnect, the signal
Process circuit is in reset mode, accordingly, and driving voltage Vdriver provides low level 0；When switching signal PH1-1, PH1-2,
When PH1-3 is disconnected, PH2 is turned on, the signal processing circuit is in sampling mode, accordingly, and driving voltage Vdriver provides high
Level Vhigh.Driving voltage Vdriver can be put on high level Vhigh on finger by electric installations such as beckets, by
There is conducting function in human body, the high level Vhigh can be by finger and the coupled capacitor of conductive layer formation in conductive layer
One end generation first sensing signal and second sensing signal that match with the coupling capacitance.
In one embodiment of the application, when the fingerprint sensor is in reset mode, when the fingerprint sensing
Device disconnects the sampling switch PH2 when being in reset mode, turn on the first reset switch PH1-1, the second reset switch
PH1-2, the 3rd reset switch PH1-3, apply fixed voltage, to adjust in the first input end and second input
State the circuit operating point of difference amplifier 405.
Fig. 7 is electrical block diagram of the fingerprint sensor shown in Fig. 5 in PH1 phases, as shown in fig. 7, referring to when described
When line sensor is in reset mode, the positive input and reverse input end short circuit of the difference amplifier 405.The present embodiment
In, fixed voltage Vcom, the fixed voltage Vcom can be accessed in the input of the difference amplifier 405 for adjusting institute
The circuit operating point for amplifier of checking the mark is stated, so that the fingerprint sensor from reset mode when sampling mode is switched to,
Stable state can be rapidly entered.
In another embodiment of the application, Fig. 8 is a kind of embodiment for the signal processing circuit that the application is provided
Structural representation, as shown in figure 8, first control module can include：
Two feedback capacity Cref, the feedback capacity Cref are connected to the first input end and described first defeated
Go out between end, the second input and second output end.
Two first reset switches PH1-1, the first reset switch PH1-1 are connected to the feedback capacity Cref
Two ends.
Two second reset switches PH1-2, the second reset switch PH1-2 one end are connected with each other, other end difference
It is connected with the first input end, the second input.
Two the 3rd reset switch PH1-3, the 3rd reset switch PH1-3 one end respectively with the first fingerprint sense
Survey module 401, the second fingerprint sensing module 403 to connect, the other end connects reference voltage respectively.
The first reset switch PH1-1, the second reset switch PH1-2, the 3rd reset switch PH1-3 conducting or disconnected
Open consistent.
In another embodiment of the application, second control module can include：
Two first sampling switches PH2, the sampling switch PH2 one end respectively with first fingerprint sensing module
401st, the second fingerprint sensing module 403 is connected, and the other end is connected with first output end, the second input respectively.
In this implementation, in reset mode, switching signal PH1-1, PH1-2, PH1-3 conducting, PH2 disconnect, now, benchmark electricity
Press and give electric capacity Cin1 chargings, so, electric capacity Cin1 one end has the magnitude of voltage of certain numerical value.In sampling mode, switching signal
PH1-1, PH1-2, PH1-3 disconnect, PH2 conductings, and now, the magnitude of voltage on electric capacity Cin1 applies voltage on the conductive layer,
So, when finger touches the touch insulating barrier, coupled capacitor can be equally produced between finger and the conductive layer, it is described
Coupled capacitor is contained in the Cin1；First fingerprint sensing module 401, second fingerprint sensing module 403 are distinguished
First sensing signal and second sensing that voltage generation based on the application matches with the coupling capacitance
Signal.
In one embodiment of the application, first signal processing unit 406, the secondary signal processing unit
407 can have row selecting switch, column select switch, when first signal processing unit 406, secondary signal processing are single
When row selecting switch, the column select switch of member 407 are switched on, first signal processing unit 406 and the secondary signal
The coupling generation of processing unit 407 difference amplifier 405.
In the present embodiment, single first signal processing unit 406, the master of the secondary signal processing unit 407
Act on and be to be amplified processing to the first faint sensing signal, the second sensing signal.By first signal transacting
Unit 406, the secondary signal processing unit 407 are coupled into after difference amplifier 405, and the difference amplifier 405 is not only
Sensing signal can be amplified, can also weaken or eliminate common-mode noise and imbalance.As shown in figure 9, the application provides a kind of knot
The circuit structure of the simple signal processing unit of structure, wherein MOS1 is input transistors, is mainly used in receiving sensing signal, amplification
Sensing signal, transistor MOS2 is that row selecting switch, transistor MOS3 are column select switch, MOS2, MOS3 input (i.e. grid
Pole) it is applied in after the voltage more than predetermined threshold value, MOS2, MOS3 are switched on, and now corresponding signal processing unit is
It is chosen.Certainly, row selecting switch, the implementation of column select switch are not limited to above-mentioned MOS transistor, for example, can also be three
Pole pipe etc., the application is not limited herein.
Based on this, in one embodiment of the application, the row selecting switch, the column select switch can be by numerals
Circuit control is switched on or off.
In the present embodiment, can by row selecting switch described in Digital Circuit Control, the conducting of the column select switch or
Person disconnects, and because Digital Circuit Control mode is small relative to analog circuit control mode noise, speed fast, can reduce and switch
Noise, the efficiency of raising finger print information processing in journey.
In one embodiment of the application, first signal processing unit 406, the secondary signal processing unit
The area for being used to amplify the input transistors of first sensing signal and the second sensing signal in 407 can be pre- not less than first
If threshold value.
In the present embodiment, by comparison diagram 4 and Fig. 3 it can be found that the signal processing circuit structure in the application it is relative and
Speech is simple many, and specifically in follow-up IC Layout, circuit chip occupying area can also reduce a lot, a side
Face can reduce flow cost, on the other hand can also allow some leeway to the optimization of the size design of portion of transistor.This implementation
In example, input transistors in first signal processing unit 406, the secondary signal processing unit 407 can be increased (as schemed
Transistor MOS1 in 9) size so that the area of input transistors be not less than the first predetermined threshold value.It is defeated in analog IC field
Enter the increase of transistor area, can not only reduce the imbalance of integrated circuit technology, the influence of noise can also be substantially reduced.Cause
This, on the basis of the signal processing circuit structure provided based on the application is simple, increases the size of input pipe, advantageously reduces
The influence that technique is lacked of proper care with noise.
In one embodiment of the application, in the difference amplifier 405, first signal processing unit 406
Tail current source and output loading can be shared with the secondary signal processing unit 407.
Figure 10 is the structural representation of the one embodiment for the difference amplifier 405 that the application is provided, as shown in Figure 10, institute
Tail current source and output loading can be shared by stating the first signal processing unit 406 and the secondary signal processing unit 407.This reality
Apply in example, the tail current source, the output loading can be realized by MOS transistor, can also be real by triode etc.
Existing, the application is not limited herein.As described above, the module number in fingerprint sensing module array is a lot, accordingly, at signal
The quantity for managing unit is also very huge, if each signal processing unit accesses single tail current and output loading, will lead
Cause the very big consumption of chip area cost.Chip design cost can be substantially reduced by sharing tail current or output loading.
Further, can also be during signal output in the present embodiment, only N number of difference amplifier every time, i.e.,
The output of 2N fingerprint sensing module finger print information, such as N are 8,10,16.So, in the case where not influenceing fingerprint imaging,
The area of chip can also further be reduced.
In one embodiment of the application, first signal processing unit 406, the secondary signal processing unit
There is common mode feedback loop, the common mode feedback loop is used to control the tail current source, to stablize the differential amplification in 407
The common mode operation voltage of device 405.
In the present embodiment, the tail current source determines the stability of the common mode operation voltage of difference amplifier 405, in order to
So that tail current source keeps stable, can be in first signal processing unit 406, the secondary signal processing unit 407
Common mode feedback loop is set, to control the tail current source, so as to further stablize the common mode operation of the difference amplifier 405
Voltage.
In one embodiment of the application, first input circuit can include first adder, and described first adds
Adjacent with first fingerprint sensing module and first fingerprint sensing module fingerprint sensing module is electrical respectively for musical instruments used in a Buddhist or Taoist mass
Connection, the sense for the fingerprint sensing module generation adjacent to first sensing signal and first fingerprint sensing module
Survey signal and carry out read group total, the summation sensing signal of generation first；
Accordingly, second input circuit can include second adder, and the second adder is respectively with described the
Two fingerprint sensing modules and the adjacent fingerprint sensing module of second fingerprint sensing module are electrically connected with, for described the
Two sensing signals and the sensing signal of the adjacent fingerprint sensing module generation of second fingerprint sensing module carry out summation meter
Calculate, the summation sensing signal of generation second；
Correspondingly, first signal processing unit and the secondary signal processing unit are coupled, by described first
Summation sensing signal and the second summation sensing signal carry out differential amplification processing.
, can be before difference processing be carried out to the first sensing signal, the second sensing signal, respectively to institute in the present embodiment
The sensing signal for stating the first sensing signal, the second sensing signal and its generation of adjacent sensing module is averaging processing, to be lifted
The data consistency of sensing signal.Schematic diagram as shown in figure 11 is specifically may be referred to, in fingerprint sensing module array 408,
The m rows n-th that fingerprint sensing module (m, n) is located at the fingerprint sensing module array 408 are arranged, if assuming the fingerprint sensing mould
First sensing signal of block (m, n) generation is finger (m, n), the adjacent fingerprint sensing module with fingerprint sensing module (m, n)
Fingerprint sensing module (m, n+1), fingerprint sensing module (m+1, n), the sensing signal point of fingerprint sensing module (m+1, n+1) generation
Not Wei finger (m, n+1), finger (m+1, n), finger (m+1, n+1), then after carrying out read group total, the first of generation
Sensing signal of summing is finger (m, n)+finger (m, n+1)+finger (m+1, n)+finger (m+1, n+1).It is corresponding
Ground, the processing mode of second input circuit is identical with the processing mode of first input circuit, will not be described here.This
Afterwards, the first summation sensing signal and the second summation sensing signal of generation can be separately input into first letter
Number processing unit and the secondary signal processing unit, to enter to the described first summation sensing signal and the second summation sensing signal
The processing of row differential amplification.
It should be noted that during read group total is carried out, can be to the whole of first fingerprint sensing module
Or the sensing signal of part adjacent fingerprint sensing module generation is calculated, the application is not limited herein.
, can be before differential amplification be carried out in the present embodiment, the sensing signal that fingerprint sensing module is generated and its phase
The sensing signal of adjacent fingerprint sensing module generation is averaging processing, and can strengthen the data consistency of sensing signal, improve
The precision of fingerprint imaging.
Based on the above-mentioned signal processing circuit for fingerprint sensor, on the other hand the application also provides a kind of fingerprint sensing
Device, the fingerprint sensor can include the signal processing circuit described in any of the above-described embodiment, wherein, the fingerprint sensing mould
The quantity of block and the quantity of the signal processing unit match.
Further, tail current source, the output loading of predetermined number can be included in the fingerprint sensor, it is described default
Quantity is less than the quantity of the signal processing unit.
On the other hand the application, which also provides, can include fingerprint sensor, institute in a kind of electronic equipment, the electronic equipment
Stating fingerprint sensor includes the signal processing circuit described in any of the above-described embodiment.
Further, there can also be the function of quick charge in the electronic equipment.
Further, the electronic equipment can include it is following in any one：Intelligent movable phone, computer (bag
Include notebook computer, desktop computer), Flat electronic equipment, personal digital assistant (PDA), intelligent wearable device etc., the application
It is not limited herein.
Each above-mentioned embodiment in this specification is described by the way of progressive, identical between each embodiment
Similar portion is cross-referenced, and what each embodiment was stressed is and other embodiment difference.
The foregoing is only several embodiments of the invention, although disclosed herein embodiment as above, but institute
Content is stated only to facilitate the embodiment for understanding the present invention and using, is not intended to limit the present invention.Any institute of the present invention
Belong to those skilled in the art, do not depart from disclosed herein spirit and scope on the premise of, can be in embodiment
Formal and details on make any modification and change, but the scope of patent protection of the present invention still must be with appended claims
The scope that book is defined is defined.
Claims (18)
1. a kind of signal processing circuit for fingerprint sensor, it is characterised in that including：First input circuit, the second input
Circuit and difference amplifier；
First input circuit is used to be electrically connected with the first fingerprint sensing module of the fingerprint sensor, by described the
First sensing signal of one fingerprint sensing module generation is supplied to the difference amplifier；
Second input circuit is used to be electrically connected with the second fingerprint sensing module of the fingerprint sensor, by described the
Second sensing signal of two fingerprint sensing modules generation is supplied to the difference amplifier；First fingerprint sensing module and institute
State the different sensing module of any two in the fingerprint sensing module array that the second fingerprint sensing module is the fingerprint sensor；
The difference amplifier includes opposite polarity and electrical with first input circuit and second input circuit respectively
The first input end of connection and the second input, and the first signal processing unit being electrically connected with the first input end,
The secondary signal processing unit being electrically connected with second input；First signal processing unit and the secondary signal
Processing unit is coupled, and first sensing signal and the second sensing signal is carried out into differential amplification processing, the difference is put
Big device is also included the output end of the signal output after the processing.
2. signal processing circuit according to claim 1, it is characterised in that first signal processing unit, described
Binary signal processing unit has row selecting switch, column select switch, at first signal processing unit, the secondary signal
When row selecting switch, the column select switch of reason unit are switched on, at first signal processing unit and the secondary signal
Manage the unit coupling generation difference amplifier.
3. signal processing circuit according to claim 2, it is characterised in that the row selecting switch, the column selection are opened
Pass is switched on or off by Digital Circuit Control.
4. signal processing circuit according to claim 1, it is characterised in that first signal processing unit, described
The area of input transistors in binary signal processing unit for amplifying first sensing signal and the second sensing signal is not small
In the first predetermined threshold value.
5. signal processing circuit according to claim 1, it is characterised in that in the difference amplifier, described first
Signal processing unit and the secondary signal processing unit share tail current source and output loading.
6. signal processing circuit according to claim 5, it is characterised in that first signal processing unit, described
There is common mode feedback loop, the common mode feedback loop is used to control the tail current source, with stable in binary signal processing unit
The common mode operation voltage of the difference amplifier.
7. signal processing circuit according to claim 1, it is characterised in that the output end includes defeated for exporting first
Go out the second output end of the second output voltage of the first output end and output of voltage, first output signal is described for determining
The corresponding finger print information of first fingerprint sensing module, second output signal is used to determine that second sensing module is corresponding
Finger print information.
8. signal processing circuit according to claim 1, it is characterised in that the signal processing circuit also includes：
First control module, reset function is worked in for starting the fingerprint sensor；
Second control module, sampled functions are worked in for starting the fingerprint sensor.
9. the signal processing circuit according to claim 1 or 8, it is characterised in that first fingerprint sensing module, described
Second fingerprint sensing module also includes the touch insulating barrier and conductive layer being connected with each other, the conductive layer and the described first input
End, the connection of the second input；When the fingerprint sensor is arranged to sampling mode, finger or the conductive layer are applied in
The voltage of default value, when finger touches the touch insulating barrier, coupled capacitor is produced between finger and the conductive layer；It is described
First fingerprint sensing module, second fingerprint sensing module are based respectively on the voltage generation of the application and the coupled capacitor
First sensing signal and second sensing signal that value matches.
10. the signal processing circuit according to claim 1 or 3, it is characterised in that when the fingerprint sensor is arranged to
During reset mode, apply fixed voltage in the first input end and second input, to adjust the difference amplifier
Circuit operating point.
11. signal processing circuit according to claim 8, it is characterised in that first control module includes：
Two feedback capacities, one end of the feedback capacity is connected to the first input end, the second input, the other end
It is connected respectively with the output end；
Two the first reset switches, first reset switch is connected to the two ends of the feedback capacity；
Two the second reset switches, one end of second reset switch is connected with each other, and the other end is inputted with described first respectively
End, the connection of the second input；
Two the 3rd reset switches, one end of the 3rd reset switch refers to first fingerprint sensing module, second respectively
Line sensing module is connected, and the other end is grounded respectively；
First reset switch, the second reset switch, the 3rd reset switch be switched on or off it is consistent.
12. signal processing circuit according to claim 8, it is characterised in that second control module includes：
Two sampling switches, one end of the sampling switch respectively with first fingerprint sensing module, the second fingerprint sensing mould
Block is connected, and the other end is connected with first output end, the second input respectively.
13. signal processing circuit according to claim 1, it is characterised in that
First input circuit include first adder, the first adder respectively with first fingerprint sensing module with
And the adjacent fingerprint sensing module of first fingerprint sensing module is electrically connected with, for first sensing signal and institute
The sensing signal for stating the adjacent fingerprint sensing module generation of the first fingerprint sensing module carries out read group total, the summation sense of generation first
Survey signal；
Accordingly, second input circuit include second adder, the second adder respectively with the second fingerprint sense
Survey module and the adjacent fingerprint sensing module of second fingerprint sensing module is electrically connected with, for believing the described second sensing
Number and the sensing signal of the adjacent fingerprint sensing module generation of second fingerprint sensing module carry out read group total, generation the
Two summation sensing signals；
Correspondingly, first signal processing unit and the secondary signal processing unit are coupled, and described first is summed
Sensing signal and the second summation sensing signal carry out differential amplification processing.
14. a kind of fingerprint sensor, it is characterised in that the fingerprint sensor is included in claim 1-12 described in any one
Signal processing circuit, wherein, the quantity of the fingerprint sensing module and the quantity of the signal processing unit match.
15. fingerprint sensor according to claim 14, it is characterised in that the fingerprint sensor includes predetermined number
Tail current source, output loading, the predetermined number be less than the signal processing unit quantity.
16. a kind of electronic equipment, it is characterised in that the electronic equipment includes fingerprint sensor, the fingerprint sensor bag
Include the signal processing circuit described in any one in claim 1-13.
17. electronic equipment according to claim 16, it is characterised in that there is the work(of quick charge in the electronic equipment
Energy.
18. the electronic equipment according to claim 16 or 17, it is characterised in that the electronic equipment include it is following in appoint
Meaning is a kind of：Intelligent movable phone, notebook computer, desktop computer, Flat electronic equipment, personal digital assistant (PDA), intelligence can
Wearable device.
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