CN108664955A - Fingerprint identification device - Google Patents
Fingerprint identification device Download PDFInfo
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- CN108664955A CN108664955A CN201810614588.8A CN201810614588A CN108664955A CN 108664955 A CN108664955 A CN 108664955A CN 201810614588 A CN201810614588 A CN 201810614588A CN 108664955 A CN108664955 A CN 108664955A
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- 238000001514 detection method Methods 0.000 claims abstract description 38
- 239000004065 semiconductor Substances 0.000 claims description 66
- 230000003321 amplification Effects 0.000 claims description 11
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 238000004088 simulation Methods 0.000 claims description 8
- 230000015654 memory Effects 0.000 claims description 4
- 239000003990 capacitor Substances 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 13
- 238000010586 diagram Methods 0.000 description 4
- 239000011800 void material Substances 0.000 description 4
- 238000012986 modification Methods 0.000 description 3
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- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 235000006508 Nelumbo nucifera Nutrition 0.000 description 1
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- 239000011248 coating agent Substances 0.000 description 1
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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
Abstract
The object of the present invention is to provide a kind of fingerprint identification devices, the fingerprint identification device of the present invention includes finger equivalent capacity and fingerprint Identification sensor, the present embodiment only needs to raise the power supply of fingerprint Identification sensor partial circuit, by the circuit power for raising fingerprint detection unit, to improve the signal strength detected, drive the required energy of fingerprint detection unit smaller, the fingerprint signal being detected can be handled under conventional electron power supply to the variable gain amplifier of rear class and analog-digital converter etc. after analog level shift circuit is translated.The present embodiment also allows for driving signal generator integrating fingerprint detection sensor on the same chip simultaneously, while ensureing to improve sensitivity, can reduce power consumption, area, cost and the complexity used.
Description
Technical field
The present invention relates to a kind of fingerprint identification devices.
Background technology
Currently, fingerprint Identification sensor system is widely used in the mobile terminals such as mobile phone, fingerprint Identification sensor is often adopted
It is realized with principles such as condenser type, optical profile type or ultrasonic wave modes.
By taking capacitance type fingerprint identification sensor as an example, as shown in Figure 1, finger due to rough lines (i.e. paddy and
Ridge), capacitance Cf, Cf not of uniform size are formed when being contacted with sensor surface (such as Coating) to be gone here and there again with dielectric layer capacitance Cc
Connection, equivalent at finger capacitance Cfinger, sensor unit detection circuit (Sensor cell) changes finger capacitance Cfinger
At voltage signal, after the operations such as amplification, analog-to-digital conversion and image procossing, the image of fingerprint can be restored.
Tradition improves fingerprint recognition sensitivity method and usually requires two independent chips：Driving chip and sensor core
Piece, driving chip generate high pressure and the alternate square wave driving signal of low pressure, by the sensor detection circuit of sensor chip, can be changed
The power supply and ground of gain amplifier circuit, analog to digital conversion circuit and digital circuit etc. are raised or are reduced simultaneously, are connect in this way in finger
Fingerprint sensor is touched, detection sensitivity can be improved when being detected.Realize that the driving chip of this method usually requires height
Pressure technique (such as BCD techniques) is supported, and the cost is relatively high for high-pressure process, in addition, two chip portfolios are more using needing
Peripheral component also takes up more many areas on PCB.
Invention content
It is an object of the present invention to provide a kind of fingerprint identification devices.
According to an aspect of the invention, there is provided a kind of fingerprint identification device, the fingerprint identification device include：
Finger equivalent capacity and fingerprint Identification sensor, wherein
One end of the finger equivalent capacity is human body, is connected with the earth, is considered as ground connection, the finger equivalent capacity it is another
One end is connected with the negative input end of the amplifier in the fingerprint Identification sensor；
The fingerprint Identification sensor includes：Fingerprint detection unit, bias current, variable gain amplifier, analog-to-digital conversion
Device, analog level shift unit and driving signal generator, wherein
The fingerprint detection unit includes：Amplifier, feedback capacity and reset switch, wherein
The amplifier includes negative input end, positive input terminal, bias current end and an output end, and the amplifier is born
Input terminal is connect with one end of the finger equivalent capacity, and the positive input of the amplifier terminates common-mode voltage, the amplifier
Bias current end with the bias current be connected；
One end of the feedback capacity is connect with the negative input end of the amplifier, the other end of the feedback capacity and institute
The output end for stating amplifier is connected；
One end of the reset switch is connect with the negative input end of the amplifier, the other end of the reset switch and institute
The output end for stating amplifier is connected；
One end of the bias current is with the current offset end connection of amplifier in fingerprint detection unit, the bias current
The other end ground connection；
The analog level shifter includes floating power supply end, analog power end, ground terminal, input terminal and output end,
In, floating power supply end is connected with the output end of driving signal generator, and input terminal is with the amplifier in the fingerprint detection unit
Output end be connected；
The variable gain amplifier includes：Positive input terminal, negative input end, positive output end and negative output terminal, wherein described
The positive input terminal of variable gain amplifier is connected with the output end of the analog level shifter, the variable gain amplifier
Negative input end is grounded；The analog-digital converter is connected with the positive input terminal of the variable gain amplifier with negative input end, is completed
Output digit signals after analog-to-digital conversion；
The driving signal generator analog power, simulation and the indication signal given of fingerprint detection unit under generate it is floating
Dynamic power supply, the power supply as the fingerprint detection unit.
Further, in above-mentioned fingerprint identification device, the power supply for the floating that the driving signal generator generates is
Square-wave signal.
Further, in above-mentioned fingerprint identification device, when 11 phases of Φ, the power supply of the floating is elevated, described to be lifted
The level of the power supply of the floating is FVDD when high；
When 22 phases of Φ, the power supply of the floating is with the analog power short circuit.
Further, in above-mentioned fingerprint identification device, when 22 phases of Φ, the reset switch is closed, the amplification
The negative input end and output end of device are shorted；
When 11 phases of Φ, the reset switch disconnects, by the finger equivalent capacity, feedback capacity and amplifier structure
At charge amplifier enter amplification mode.
Further, in above-mentioned fingerprint identification device, the analog level shift unit is used for the output of the amplifier
The voltage value of the output signal at end moves in the process range of the variable gain amplifier.
Further, in above-mentioned fingerprint identification device, the analog level shift unit is used for the output of the amplifier
The output signal at end is transformed into the power supply of (analog power-simulation) by the power domain translation of (power supply-simulation of floating)
Domain.
Further, further include memory in above-mentioned fingerprint identification device, be used for the defeated of the output end of the amplifier
Go out signal successively to turn by the analog level shifter, variable gain amplifier amplification and the analog-digital converter
After changing, obtained digital signal is stored.
Further, in above-mentioned fingerprint identification device, the driving signal generator includes metal-oxide-semiconductor M1~M5 and capacitance C1
~C5, wherein
The grid end of the metal-oxide-semiconductor M1 is connected with drain terminal, forms diode-connected, the grid end of metal-oxide-semiconductor M1 and drain terminal it is public
End is connected together with power supply AVDD, and inputs of the AVDD as driving signal generator, the source of metal-oxide-semiconductor M1 is again with metal-oxide-semiconductor M2's
Drain terminal is connected；
The grid end of the metal-oxide-semiconductor M2 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M2 and the common end of drain terminal with one end of capacitance C1
It is connected, the other end of capacitance C1 is with clock φaConnection, the source of metal-oxide-semiconductor M2 are connect with the drain terminal of metal-oxide-semiconductor M3；
The grid end of the metal-oxide-semiconductor M3 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M3 and the common end of drain terminal with one end of capacitance C2
It is connected, the other end of capacitance C2 is with clock φbConnection, the source of metal-oxide-semiconductor M3 are connect with the drain terminal of metal-oxide-semiconductor M4；
The grid end of the metal-oxide-semiconductor M4 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M4 and the common end of drain terminal with one end of capacitance C3
It is connected, the other end of capacitance C3 is with clock φaConnection, the source of metal-oxide-semiconductor M4 are connect with the drain terminal of metal-oxide-semiconductor M5；
The grid end of the metal-oxide-semiconductor M5 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M5 and the common end of drain terminal with one end of capacitance C4
It is connected, the other end of capacitance C4 is with clock φbConnection；
The source of the metal-oxide-semiconductor M5 is output end, exports the voltage FVDD when power supply of the floating is elevated,
FVDD is connected with the one end output filter capacitor C5, the other end ground connection of capacitance C5；
The substrate of described metal-oxide-semiconductor M1, M2, M3, M4 and M5 are all grounded.
Further, in above-mentioned fingerprint identification device, the driving signal generator, in non-overlapping clock φaWith
φbUnder timing control, the voltage of analog power is lifted after metal-oxide-semiconductor M1~M5 and capacitance C1~C4 that diode connects
To FVDD, and under indication signal control, FVDD and the analog power are regenerated to the power supply of the floating.
Compared with prior art, fingerprint identification device of the invention includes finger equivalent capacity (Cfinger) 21 and fingerprint
Identification sensor 23, the present embodiment only needs to raise the power supply of fingerprint Identification sensor partial circuit, by raising fingerprint
The circuit power of detection unit 222, to improve the signal strength detected, 222 required energy of driving fingerprint detection unit
Smaller, the fingerprint signal being detected is after analog level shift circuit is translated, after being given under conventional electron power supply
Variable gain amplifier and analog-digital converter of grade etc. are handled.The present embodiment also allow for simultaneously by fingerprint detection sensor with
Driving signal generator is integrated on the same chip, while ensureing to improve sensitivity, can reduce power consumption, area, at
Sheet and the complexity used.
Description of the drawings
By reading a detailed description of non-restrictive embodiments in the light of the attached drawings below, of the invention other
Feature, objects and advantages will become more apparent upon：
Fig. 1 shows existing fingerprint recognition principle schematic；
Fig. 2 shows the raising fingerprint recognition sensitivity settings schematic diagrames of first embodiment of the invention；
Fig. 3 shows the raising fingerprint recognition sensitivity settings signal schematic representation of Fig. 2；
Fig. 4 shows the raising fingerprint recognition sensitivity settings schematic diagram of second embodiment of the invention；
Fig. 5 shows the raising fingerprint recognition sensitivity settings signal schematic representation of Fig. 4
Fig. 6 shows that the driving signal generator of Fig. 4 generates FVDD schematic diagrames.
Same or analogous reference numeral represents same or analogous component in attached drawing.
Specific implementation mode
Present invention is further described in detail below in conjunction with the accompanying drawings.
Fig. 2 shows the fingerprint identification devices for the raising sensitivity that the present invention one is implemented, as shown in Fig. 2, the raising is sensitive
The fingerprint identification device of degree includes：
Finger equivalent capacity (Cfinger) 11, driving signal generator 12 and fingerprint detection sensor 13, wherein
Described 11 one end of finger equivalent capacity (Cfinger) is human body, is connected with the earth, is considered as ground connection, the other end is with referring to
The negative input end connection of amplifier (OP) 131 in line detection sensor 13；
The fingerprint detection sensor 13 includes amplifier (OP) 131, feedback capacity (Cref) 132, reset switch (SW)
133, bias current 134, variable gain amplifier (PGA) 135 and analog-digital converter (ADC) 136, wherein
The amplifier (OP) 131 includes negative input end, positive input terminal, bias current end and an output end, described to put
The negative input end of big device (OP) 131 is connect with 11 one end of finger equivalent capacity (Cfinger), and the amplifier (OP) 131 is just
Input termination common-mode voltage Vcm, the bias current end of the amplifier (OP) 131 are connected with bias current 134；
One end of the feedback capacity (Cref) 132 is connect with the negative input end of the amplifier (OP) 131, the other end with
The output end of the amplifier (OP) 131 is connected；
One end of the reset switch (SW) 133 is connect with the negative input end of the amplifier (OP) 131, the other end with put
The output end of big device (OP) 131 is connected.134 one end of bias current is connected with the current offset end of amplifier (OP) 131, the other end
Ground connection.Variable gain amplifier (PGA) 135 has positive input terminal, negative input end, positive output end and negative output terminal, wherein positive input
The output end with amplifier (OP) 131 is held to be connected, negative input end ground connection, negative output terminal and positive output end are all with analog-digital converter
(ADC) 136 connection.Analog-digital converter (ADC) 136 connects with the positive input terminal and negative input end of variable gain amplifier (PGA) 135
It connects, completes output digit signals Dout after analog-to-digital conversion.
The driving signal generator 12 is given in analog power (AVDD), simulation ground (AVSS) and fingerprint detection sensor 13
Generated under indication signal floating power supply (XVDD) and float ground (XVSS), as fingerprint detection sensor 13 power supply and
Ground.
The fingerprint detection method of tradition raising sensitivity utilizes the fingerprint identification device of Fig. 2, driving signal generator 12
Power supply and ground are respectively AVDD and AVSS, and voltage all immobilizes, and such as respectively 2.8V and 0V, driving signal generator 12 are common
Realized by inductance boost circuit or charge pump booster circuit, under indication signal and other timing control, drive signal production
Raw device can generate power supply and ground that a pair of of voltage floats, as shown in figure 3, respectively XVDD and XVSS, XVDD are synchronous with XVSS
Square-wave signal, Φ 1 phase XVDD and XVSS be elevated, referred to as lift ground, and 2 phase XVDD of Φ are with AVDD short circuits, and XVSS is with AVSS
Short circuit does not lift ground referred to as, and the level of XVDD is FVDD when remembering lift ground, and the level of XVSS is FVSS, XVDD- when lifting ground and not lifting ground
The pressure difference of XVSS all remains unchanged (such as 2.8V).When 2 phases of Φ, reset switch (SW) 133 is closed, and amplifier (OP) 131 is born
Input terminal and output end are shorted, by the short characteristic of void of amplifier, the negative input end and positive input terminal voltage phase of amplifier (OP) 131
Deng, i.e. Vin=Vcm, and Vin=Vout, so Vin=Vout=Vcm, the electricity at 11 both ends of finger equivalent capacity (Cfinger)
Lotus Q1=Vcm*Cfinger；When 1 phases of Φ, reset switch (SW) 133 disconnects, by finger equivalent capacity (Cfinger) 11, instead
Feed holds the charge amplifier that (Cref) 132 and amplifier (OP) 131 are constituted and enters amplification mode, equally by the short spy of void of amplifier
Property, the negative input end and positive input terminal voltage of amplifier (OP) 131 are equal, i.e. Vin '=Vcm '=Vcm+ △ V, and wherein △ V are
The difference of FVDD-AVDD or FVSS-AVSS, charge Q 2=Vin ' the * Cfinger at 11 both ends of finger equivalent capacity (Cfinger),
The charge Q 3=Vin '-(Vout '+△ V) at 132 both ends of feedback capacity (Cref)) * Cref, Φ 2 phase to 1 phase processes of Φ, root
There is Q1=Q2+Q3 according to principle of charge conservation, obtains：
Vout '=Vcm+ (Cfinger/Cref) * △ V (formula 1)
Wherein △ V are the difference of FVDD-AVDD or FVSS-AVSS.By formula 1 it is found that lifting higher, i.e. the value of △ V is got over
Greatly, the amplitude of signal Vout ' is bigger, and in the case where noise is certain, signal-to-noise ratio (i.e. sensitivity) can be improved accordingly.Vout ' is passed through
Later after the amplification of grade variable gain amplifier (PGA) 135 and analog-digital converter (ADC) 136 are converted, by output digit signals Dout
It is stored in memory.
As shown in figure 4, the present invention provides a kind of fingerprint identification device, including：Finger equivalent capacity (Cfinger) 21, and
Fingerprint Identification sensor 23, wherein
One end of the finger equivalent capacity (Cfinger) 21 is human body, is connected with the earth, is considered as ground connection, the other end with
The negative input end of amplifier (OP) 231 in the fingerprint Identification sensor 23 connects.
The fingerprint Identification sensor 23 includes：Fingerprint detection unit 222, bias current 234, variable gain amplifier
(PGA) 235, analog-digital converter (ADC) 236, analog level shift unit 237 and driving signal generator 238, wherein
The fingerprint detection unit 222 includes：Amplifier (OP) 231, feedback capacity (Cref) 232 and reset switch (SW)
233, wherein
The amplifier (OP) 231 includes negative input end, positive input terminal, bias current end and an output end, described to put
The negative input end of big device (OP) 231 is connect with described 21 one end of finger equivalent capacity (Cfinger), the amplifier (OP) 231
Positive input terminate common-mode voltage Vcm, the bias current end of the amplifier (OP) 231 is connected with bias current 234；
Described 232 one end of feedback capacity (Cref) is connect with the negative input end of amplifier (OP) 231, the other end and amplifier
(OP) 231 output end is connected；
Described 233 one end of reset switch (SW) is connect with the negative input end of amplifier (OP) 231, the other end and amplifier
(OP) 231 output end is connected；
234 one end of the bias current is connected with the current offset end of amplifier (OP) 231 in fingerprint detection unit 222,
The other end is grounded；
The analog level shifter 237 includes floating power supply end (XVDD), analog power end (AVDD), ground terminal
(AVSS), input terminal and output end, wherein the output end XVDD phases of floating power supply end (XVDD) with driving signal generator 238
Even, input terminal is connected with the output end of the amplifier (OP) 231 in the fingerprint detection unit 222, and output end is with described variable
The positive input terminal of gain amplifier (PGA) 235 is connected；
The variable gain amplifier (PGA) 235 includes：Positive input terminal, negative input end, positive output end and negative output terminal,
Wherein, the positive input terminal of the variable gain amplifier (PGA) 235 is connected with the output end of analog level shifter 237, described
The negative input end of variable gain amplifier (PGA) 235 is grounded, the negative output terminal of the variable gain amplifier (PGA) 235 and just
Output end is connected with analog-digital converter (ADC) 236 respectively.Analog-digital converter (ADC) 236 is with variable gain amplifier (PGA) 235
Positive input terminal connected with negative input end, complete analog-to-digital conversion after output digit signals Dout；
Driving signal generator 238 in the fingerprint Identification sensor 23 is on analog power (AVDD), simulation ground
(AVSS) and under the indication signal given of fingerprint detection unit 222 power supply (XVDD) for generating floating, as fingerprint detection unit 222
Power supply.
Specifically, as shown in figure 4, the power supply of fingerprint Identification sensor 23 and ground are respectively AVDD and AVSS, voltage is all solid
It is fixed constant, such as respectively 2.8V and 0V, variable gain amplifier (PGA) 235, analog-digital converter (ADC) 236 and drive signal production
Raw device 238 can be directly operated under AVDD and AVSS.
Driving signal generator 238 fixed voltage power supply (AVDD), generate one under (AVSS) and indication signal
The power supply (XVDD) of floating voltage, XVDD is square-wave signal.
Here, the fingerprint identification device of the present invention includes finger equivalent capacity (Cfinger) 21 and fingerprint Identification sensor
23, the present embodiment only needs to raise the power supply of fingerprint Identification sensor partial circuit, by raising fingerprint detection unit 222
Circuit power, to improve the signal strength detected, driving fingerprint detection 222 required energy of unit are smaller, are detected
To fingerprint signal after analog level shift circuit is translated, can under conventional electron power supply give rear class variable gain
Amplifier and analog-digital converter etc. are handled.The present embodiment also allows for generating fingerprint detection sensor with drive signal simultaneously
Device is integrated on the same chip, while ensureing to improve sensitivity, can reduce power consumption, area, cost and what is used answer
Miscellaneous degree.
As shown in figure 5,11 phase XVDD of Φ are elevated, power supply is referred to as lifted, the level of XVDD is FVDD when note lifts power supply；
22 phase XVDD of Φ referred to as do not lift power supply with AVDD short circuits.
Floating power supplies of the XVDD of generation as fingerprint detection unit 222, as shown in phantom in Figure 4.
When 22 phases of Φ, reset switch (SW) 233 is closed, and the negative input end and output end of amplifier (OP) 231 are shorted,
By the short characteristic of void of amplifier, the negative input end and positive input terminal voltage of amplifier (OP) 231 are equal, i.e. Vin=Vcm, and Vin=
Vout, so Vin=Vout=Vcm, the charge Q 11=Vcm*Cfinger at 21 both ends of finger equivalent capacity (Cfinger)；
When 11 phases of Φ, reset switch (SW) 233 disconnects, by finger equivalent capacity (Cfinger) 21, feedback capacity
(Cref) 232 and the charge amplifier that constitutes of amplifier (OP) 231 enter amplification mode, equally by the short characteristic of void of amplifier, put
The negative input end and positive input terminal voltage of big device (OP) 231 are equal, i.e. Vin '=Vcm '=Vcm+ △ V, wherein △ V are FVDD-
The difference of AVDD, charge Q 22=Vin ' the * Cfinger at 21 both ends of finger equivalent capacity (Cfinger), feedback capacity (Cref) 232
22 phase of charge Q 33=(Vin '-Vout ') * Cref, Φ at both ends has Q11 to 11 phase processes of Φ according to principle of charge conservation
=Q22+Q33, obtains：
Vout '=(Vcm+ △ V)+(Cfinger/Cref) * △ V (formula 2)
Wherein, △ V are the difference of FVDD-AVDD.
By formula 2 it is found that lifting higher, i.e. the value of △ V is bigger, includes the amplitude of the signal Vout ' of fingerprint effective information
Also bigger, in the case where noise is certain, signal-to-noise ratio (i.e. sensitivity) can be improved accordingly.From formula 2 it can also be seen that with
AVSS is reference, and the voltage value that Vcm is also elevated into Vcm+ △ V, such Vout ' simultaneously can be more than the processing model of subsequent conditioning circuit
It encloses, so needing an analog level shift unit that the voltage value of the output signal Vout ' of the output end of amplifier (OP) 231 is flat
Moving on to variable gain amplifier (PGA) 235 can be in process range, and analog level shift unit 237 can be by fingerprint detection unit 222
Output signal Vout ' is transformed into AVDD-AVSS power domains by the translation of XVDD-AVSS power domains, amplifies convenient for follow-up variable gain
The processing of device (PGA) 235.Vout ' passes through the displacement of analog level shift unit 237 successively, variable gain amplifier (PGA) 235 amplifies
After being converted with analog-digital converter (ADC) 236, in the digital signal Dout deposit memories of analog-digital converter output.
Fig. 6 be driving signal generator generate FVDD schematic diagrames, driving signal generator 238 include metal-oxide-semiconductor M1~M5 and
Capacitance C1~C5, wherein the grid end of metal-oxide-semiconductor M1 is connected with drain terminal, forms diode-connected, the grid end of metal-oxide-semiconductor M1 and drain terminal
Common end is connected together with power supply AVDD, and inputs of the AVDD as driving signal generator, the source of metal-oxide-semiconductor M1 is again with metal-oxide-semiconductor
The drain terminal of M2 is connected；The grid end of metal-oxide-semiconductor M2 is with drain terminal short circuit, and the grid end of metal-oxide-semiconductor M2 and the common end of drain terminal are with the one of capacitance C1
End is connected, and the other end of capacitance C1 is with clock φaConnection, the source of metal-oxide-semiconductor M2 are connect with the drain terminal of metal-oxide-semiconductor M3；Metal-oxide-semiconductor M3's
Grid end with drain terminal short circuit, the grid end of metal-oxide-semiconductor M3 and the common end of drain terminal with being connected with one end of capacitance C2, the other end of capacitance C2
With clock φbConnection, the source of metal-oxide-semiconductor M3 are connect with the drain terminal of metal-oxide-semiconductor M4；The grid end of metal-oxide-semiconductor M4 is with drain terminal short circuit, metal-oxide-semiconductor
The grid end of M4 is connected with the common end of drain terminal with one end of capacitance C3, and the other end of capacitance C3 is with clock φaConnection, metal-oxide-semiconductor M4
Source connect with the drain terminal of metal-oxide-semiconductor M5；The grid end of metal-oxide-semiconductor M5 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M5 and the common end of drain terminal
One end with capacitance C4 is connected, and the other end of capacitance C4 is with clock φbConnection；The source of metal-oxide-semiconductor M5 is output end, and output is raised
Voltage FVDD, FVDD be connected with the one end output filter capacitor C5, the other end of capacitance C5 ground connection；Metal-oxide-semiconductor M1, M2, M3, M4 and
The substrate acquiescence of M5 is all grounded.In non-overlapping clock φaAnd φbUnder timing control, AVDD passes through the metal-oxide-semiconductor M1 of diode connection
Voltage is lifted to FVDD after~M5 and capacitance C1~C4.Under indication signal control, FVDD and AVDD regenerate square-wave signal
XVDD, due to only needing to generate a floating power supply, it is possible to reduce loss and the use of peripheral cell.
In addition, driving signal generator can also be realized using other voltage boost circuits.
Obviously, those skilled in the art can carry out the application essence of the various modification and variations without departing from the application
God and range.In this way, if these modifications and variations of the application belong to the range of the application claim and its equivalent technologies
Within, then the application is also intended to include these modifications and variations.
It is obvious to a person skilled in the art that invention is not limited to the details of the above exemplary embodiments, Er Qie
In the case of without departing substantially from spirit or essential attributes of the invention, the present invention can be realized in other specific forms.Therefore, no matter
From the point of view of which point, the present embodiments are to be considered as illustrative and not restrictive, and the scope of the present invention is by appended power
Profit requires rather than above description limits, it is intended that all by what is fallen within the meaning and scope of the equivalent requirements of the claims
Variation includes within the present invention.Any reference signs in the claims should not be construed as limiting the involved claims.This
Outside, it is clear that one word of " comprising " is not excluded for other units or step, and odd number is not excluded for plural number.That is stated in device claim is multiple
Unit or device can also be realized by a unit or device by software or hardware.The first, the second equal words are used for table
Show title, and does not represent any particular order.
Claims (9)
1. a kind of fingerprint identification device, wherein the fingerprint identification device includes：Finger equivalent capacity and fingerprint Identification sensor,
Wherein,
One end of the finger equivalent capacity is human body, is connected with the earth, is considered as ground connection, the other end of the finger equivalent capacity
Negative input end with the amplifier in the fingerprint Identification sensor connects；
The fingerprint Identification sensor includes：Fingerprint detection unit, bias current, variable gain amplifier, analog-digital converter, mould
Quasi- level shifter and driving signal generator, wherein
The fingerprint detection unit includes：Amplifier, feedback capacity and reset switch, wherein
The amplifier includes negative input end, positive input terminal, bias current end and an output end, the negative input of the amplifier
End is connect with one end of the finger equivalent capacity, the positive input of amplifier termination common-mode voltage, the amplifier it is inclined
Current terminal is set with the bias current to be connected；
One end of the feedback capacity is connect with the negative input end of the amplifier, and the other end of the feedback capacity is put with described
The output end of big device is connected；
One end of the reset switch is connect with the negative input end of the amplifier, and the other end of the reset switch is put with described
The output end of big device is connected；
One end of the bias current in fingerprint detection unit amplifier current offset end connection, the bias current it is another
One end is grounded；
The analog level shifter includes floating power supply end, analog power end, ground terminal, input terminal and output end, wherein floating
Dynamic power end is connected with the output end of driving signal generator, output of the input terminal with the amplifier in the fingerprint detection unit
End is connected；
The variable gain amplifier includes：Positive input terminal, negative input end, positive output end and negative output terminal, wherein described variable
The positive input terminal of gain amplifier is connected with the output end of the analog level shifter, and bearing for the variable gain amplifier is defeated
Enter end ground connection；The analog-digital converter is connected with the positive input terminal of the variable gain amplifier with negative input end, completes modulus
Output digit signals after conversion；
The driving signal generator analog power, simulation and the indication signal given of fingerprint detection unit under generate and float
Power supply, the power supply as the fingerprint detection unit.
2. fingerprint identification device according to claim 1, wherein the floating that the driving signal generator generates
Power supply is square-wave signal.
3. fingerprint identification device according to claim 1 or 2, wherein when 11 phases of Φ, the power supply of the floating is lifted
The level of height, the power supply of the floating described when being elevated is FVDD；
When 22 phases of Φ, the power supply of the floating is with the analog power short circuit.
4. fingerprint identification device according to claim 3, wherein when 22 phases of Φ, the reset switch is closed, institute
The negative input end and output end for stating amplifier are shorted；
When 11 phases of Φ, the reset switch disconnects, and is made of the finger equivalent capacity, feedback capacity and amplifier
Charge amplifier enters amplification mode.
5. fingerprint identification device according to claim 4, wherein the analog level shift unit is used for the amplification
The voltage value of the output signal of the output end of device moves in the process range of the variable gain amplifier.
6. fingerprint identification device according to claim 5, wherein the analog level shift unit is used for the amplification
The output signal of the output end of device is transformed into (analog power-simulation by the power domain translation of (power supply-simulation of floating)
Ground) power domain.
7. fingerprint identification device according to claim 1, wherein further include memory, be used for the defeated of the amplifier
The output signal of outlet successively by the analog level shifter, can variable-gain amplifier amplification and the modulus
After converter conversion, obtained digital signal is stored.
8. fingerprint identification device according to claim 3, wherein the driving signal generator includes metal-oxide-semiconductor M1~M5
With capacitance C1~C5, wherein
The grid end of the metal-oxide-semiconductor M1 is connected with drain terminal, forms diode-connected, the grid end of metal-oxide-semiconductor M1 and the common end of drain terminal with
Power supply AVDD is connected together, inputs of the AVDD as driving signal generator, and the source of metal-oxide-semiconductor M1 is again with the drain terminal of metal-oxide-semiconductor M2
It is connected；
The grid end of the metal-oxide-semiconductor M2 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M2 and the common end of drain terminal with one end phase of capacitance C1
Even, the other end of capacitance C1 is with clock φaConnection, the source of metal-oxide-semiconductor M2 are connect with the drain terminal of metal-oxide-semiconductor M3；
The grid end of the metal-oxide-semiconductor M3 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M3 and the common end of drain terminal with one end phase of capacitance C2
Even, the other end of capacitance C2 is with clock φbConnection, the source of metal-oxide-semiconductor M3 are connect with the drain terminal of metal-oxide-semiconductor M4；
The grid end of the metal-oxide-semiconductor M4 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M4 and the common end of drain terminal with one end phase of capacitance C3
Even, the other end of capacitance C3 is with clock φaConnection, the source of metal-oxide-semiconductor M4 are connect with the drain terminal of metal-oxide-semiconductor M5；
The grid end of the metal-oxide-semiconductor M5 is with drain terminal short circuit, the grid end of metal-oxide-semiconductor M5 and the common end of drain terminal with one end phase of capacitance C4
Even, the other end of capacitance C4 is with clock φbConnection；
The source of the metal-oxide-semiconductor M5 is output end, exports the voltage FVDD when power supply of the floating is elevated, FVDD with
The one end output filter capacitor C5 is connected, the other end ground connection of capacitance C5；
The substrate of described metal-oxide-semiconductor M1, M2, M3, M4 and M5 are all grounded.
9. fingerprint identification device according to claim 8, wherein the driving signal generator, for when non-overlapping
Clock φaAnd φbUnder timing control, by the voltage of analog power after metal-oxide-semiconductor M1~M5 and capacitance C1~C4 that diode connects
It is lifted to FVDD, and under indication signal control, FVDD and the analog power are regenerated to the power supply of the floating.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US11636702B2 (en) | 2018-12-26 | 2023-04-25 | Apple Inc. | Optical-fingerprint detection system |
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