CN106778672A - A kind of fingerprint detection circuit and fingerprint detection sensor - Google Patents
A kind of fingerprint detection circuit and fingerprint detection sensor Download PDFInfo
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- CN106778672A CN106778672A CN201611262306.XA CN201611262306A CN106778672A CN 106778672 A CN106778672 A CN 106778672A CN 201611262306 A CN201611262306 A CN 201611262306A CN 106778672 A CN106778672 A CN 106778672A
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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 present invention discloses a kind of fingerprint detection circuit, including at least two metal layers, governor circuit, outside source, first signal source, secondary signal source, 3rd signal source and multiple fingerprint detection units, fingerprint detection unit includes first switch, second switch, 3rd switch and charge amplifier, fingerprint capacitor is formed between finger and top-level metallic, secondary signal source, first signal source be added on a layers of metal and respectively with top-level metallic formed the first electric capacity, second electric capacity, the 3rd electric capacity is formed between top-level metallic and ground, reference capacitance is formed between top-level metallic and a layers of metal；A kind of fingerprint detection sensor, including the fingerprint detection circuit are also disclosed.Be combined for active and passive type structure by a kind of fingerprint detection circuit of the present invention and fingerprint detection sensor, and make fingerprint detection circuit can carry out different designs using design according to different demands, save the various costs of fingerprint detection chip.
Description
Technical field
The present invention relates to fingerprint detection field, especially a kind of fingerprint detection circuit and fingerprint detection sensor.
Background technology
Capacitance type fingerprint sensor with security very high, can realize safety support due to convenient to use
Pay, thus be increasingly being used in various electronic products, especially various intelligent terminals.
Existing capacitance type fingerprint detection means, mainly there is two kinds of detection modes, and one kind is active, and another kind is passive
Formula.Wherein, active penetration power is strong, but needs extra control chip, height of the cost with respect to passive type；And passive type penetration power
Although weak, extra control chip, thus advantage of lower cost are not needed.In order to solve this problem, many company's meetings
Different situations are directed to respectively, different chips are designed, and the stock thus resulted in after design cycle, expense, and volume production is expensive
It is big to increase.
The content of the invention
In order to solve the above-mentioned technical problem, it is an object of the invention to provide the compatible active working method of one kind and passive type
The fingerprint detection circuit of working method, correspondingly, also provides a kind of fingerprint detection sensor.
The technical solution adopted in the present invention is：A kind of fingerprint detection circuit, including at least two metal layers, master control electricity
Road, outside source, the first signal source, secondary signal source, the 3rd signal source and multiple fingerprint detection units, the fingerprint detection
Unit includes first switch, second switch, third switch and charge amplifier, and the governor circuit is used to export the first clock letter
Number, second clock signal, the 3rd clock signal, for controlling the switch shape of first switch, second switch, third switch respectively
State, and external analog signal, the first analog signal, the second analog signal, the 3rd analog signal are exported, for respectively as outside
Signal source, the first signal source, secondary signal source, the 3rd signal source；
Fingerprint capacitor is formed between the finger and top-level metallic, the secondary signal source, the first signal source are added in a layers
The first electric capacity, the second electric capacity are formed on metal and with top-level metallic respectively, and a layers of metal is any below top-level metallic
Layer of metal, forms the 3rd electric capacity between the top-level metallic and ground, benchmark is formed between the top-level metallic and a layers of metal
Electric capacity, the 3rd signal source is connected by the 3rd switch with the normal phase input end of charge amplifier, a left side for the second switch
Side joint ground, the right side of the second switch is connected with the normal phase input end of charge amplifier, the charge amplifier it is anti-phase defeated
Enter end to be connected with top-level metallic, the inverting input of the charge amplifier is connected with the left side of first switch, and described first opens
The right side of pass is connected with the output end of charge amplifier, and the output end of the charge amplifier is connected with a layers of metal, described many
The output end of individual charge amplifier as fingerprint detection circuit output end output signal.
Further, the fingerprint detection circuit also includes protective layer, and the protective layer is arranged on top-level metallic, institute
State finger and fingerprint capacitor is formed with top-level metallic by protective layer.
Further, the governor circuit includes control circuit and digital analog converter, and the control circuit is used to control
The on off state and output external analog signal and control digital-to-analogue conversion of first switch, second switch, third switch processed
Device exports the first analog signal, the second analog signal and the 3rd analog signal, and the digital analog converter is used to export first
Analog signal, the second analog signal and the 3rd analog signal, the output end of the control circuit are defeated with digital analog converter
Enter end connection.
Further, the protective layer includes coating, glass or ceramics.
Further, the active job control sequential of the fingerprint detection circuit is：
The second clock signal is low level signal；3rd clock signal is high level signal；
First analog signal is low level signal；When first clock signal is low level, second simulation
The magnitude of voltage of signal is first voltage v1, when first clock signal is high level, the magnitude of voltage of second analog signal
It is second voltage v2；3rd analog signal is direct current signal；
On outside source output external analog signal to finger, the external analog signal and the first clock signal
It is disjoint signals, the low level voltage of the external analog signal is 0, and the high level voltage of the external analog signal is outer
Portion analog voltage vtx.
Further, the fingerprint detection circuit also include active control circuit, the outside source with it is active
The output end of the input connection of circuit, the active control circuit is controlled to be connected with the ground of fingerprint detection circuit, for root
According to the voltage on the ground of external analog signal control fingerprint detection circuit.
Further, the active job control sequential of the fingerprint detection circuit is：
The second clock signal is low level signal；3rd clock signal is high level signal；
First analog signal is low level signal；When first clock signal is low level, second simulation
The magnitude of voltage of signal is first voltage v1, when first clock signal is high level, the magnitude of voltage of second analog signal
It is second voltage v2；3rd analog signal is direct current signal；
The outside source exports external analog signal to active control circuit, the external analog signal and the
One clock signal is disjoint signals, and the low level voltage of the external analog signal is 0, the height electricity of the external analog signal
Ordinary telegram pressure is external analog voltages vtx；The active supply voltage for controlling circuit is the first supply voltage VDDHV, described
The active output voltage for controlling circuit is ground voltage VGND；When the low level voltage of the external analog signal is 0, actively
The ground voltage VGND of formula control circuit output is 0, and the voltage for controlling the ground of fingerprint detection circuit is 0；The external analog letter
Number high level voltage when being vtx, the ground voltage VGND of active control circuit output is not 0, active control circuit control
The voltage on the ground of fingerprint detection circuit processed is ground voltage VGND.
Further, the passive type job control sequential of the fingerprint detection circuit is：
First clock signal and second clock signal are identical clock signal, first clock signal and the 3rd
Clock signal is non-overlapping clock signal；
When first clock signal is high level, the magnitude of voltage of second analog signal is tertiary voltage v3, described
The magnitude of voltage of the first analog signal is the 5th voltage v5；When first clock signal is low level, second analog signal
Magnitude of voltage be the 4th voltage v4, the magnitude of voltage of first analog signal is the 6th voltage v6；3rd analog signal is
Low level signal or high level signal.
Further, the output voltage of the output end of the charge amplifier is：
Wherein, VTX is the magnitude of voltage of external analog signal, and Cfinger is the capacitance of fingerprint capacitor, and C1 is the first electric capacity
Capacitance, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
Further, the output voltage of the output end of the charge amplifier is：
Wherein, VDDHV is the magnitude of voltage of the first supply voltage, and Cfinger is the capacitance of fingerprint capacitor, and C1 is the first electricity
The capacitance of appearance, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
Further, the output voltage of the output end of the charge amplifier is：
Wherein, Cfinger is the capacitance of fingerprint capacitor, and C3 is the capacitance of the 3rd electric capacity, and C1 is the electricity of the first electric capacity
Capacitance, C2 is the capacitance of the second electric capacity, and the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
The present invention use another technical scheme be：A kind of fingerprint detection sensor, including described fingerprint detection circuit.
The beneficial effects of the invention are as follows：A kind of fingerprint detection circuit includes at least two metal layers, master control electricity in the present invention
Road, outside source, the first signal source, secondary signal source, the 3rd signal source and multiple fingerprint detection units, fingerprint detection unit
Including first switch, second switch, third switch and charge amplifier, fingerprint capacitor is formed between finger and top-level metallic, the
Binary signal source, the first signal source be added on a layers of metal and respectively with top-level metallic formed the first electric capacity, the second electric capacity, a layers
Metal is any layer of metal below top-level metallic, and the 3rd electric capacity, top-level metallic and a layers are formed between top-level metallic and ground
Reference capacitance is formed between metal, the 3rd signal source is connected by the 3rd switch with the normal phase input end of charge amplifier, second
The left side ground of switch, the right side of second switch is connected with the normal phase input end of charge amplifier, charge amplifier it is anti-phase defeated
Enter end to be connected with top-level metallic, the inverting input of charge amplifier is connected with the left side of first switch, the right side of first switch
It is connected with the output end of charge amplifier, the output end of charge amplifier is connected with a layers of metal；Fingerprint detection electricity of the invention
Be combined for active and passive type structure by road, makes being carried out according to different demands using design for fingerprint detection circuit
Different designs, governor circuit is believed according to different design requirements to the finger clock control different with the input of fingerprint detection unit
Number, and then active or passive type scheme can be packaged into, greatly save design, checking, stock of fingerprint detection chip etc.
Various costs.In addition, a kind of fingerprint detection sensor of the invention, including fingerprint detection circuit, comparing, it is active to separately design
For chip and passive type chip, the design cycle is short and expense is few.
Brief description of the drawings
Specific embodiment of the invention is described further below in conjunction with the accompanying drawings：
Fig. 1 is an a kind of specific embodiment structural representation of fingerprint detection circuit in the present invention；
Fig. 2 is an a kind of specific embodiment circuit diagram of fingerprint detection circuit in the present invention；
Fig. 3 is a kind of active job control oscillogram of fingerprint detection circuit in the present invention；
Fig. 4 is an a kind of specific embodiment schematic diagram of the active circuit of fingerprint detection circuit in the present invention；
Fig. 5 is a kind of another specific embodiment structural representation of the active circuit of fingerprint detection circuit in the present invention；
Fig. 6 is a kind of another specific embodiment circuit diagram of the active circuit of fingerprint detection circuit in the present invention；
Fig. 7 is a kind of passive type job control oscillogram of fingerprint detection circuit in the present invention；
Fig. 8 is an a kind of specific embodiment schematic diagram of the passive type circuit of fingerprint detection circuit in the present invention.
Specific embodiment
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase
Mutually combination.
A kind of fingerprint detection circuit, is an a kind of specific reality of fingerprint detection circuit in the present invention with reference to Fig. 1 and Fig. 2, Fig. 1
A structural representation is applied, Fig. 2 is an a kind of specific embodiment circuit diagram of fingerprint detection circuit in the present invention, including at least
Two metal layers, governor circuit 100, outside source, the first signal source, secondary signal source, the 3rd signal source and multiple fingerprints
Detection unit 200, multiple fingerprint detection units 200 constitute fingerprint detection array, and fingerprint detection unit 200 includes first switch
SW1, second switch SW2, the 3rd switch SW3 and charge amplifier CA, governor circuit 100 be used for export the first clock signal S1,
Second clock signal S2, the 3rd clock signal S3, for controlling first switch SW1, second switch SW2, the 3rd switch SW3 respectively
On off state, and export external analog signal VTX, the first analog signal VDAC1, the second analog signal VDAC2, the 3rd simulation
Signal VDAC3, for respectively as outside source, the first signal source, secondary signal source, the 3rd signal source；
Fingerprint capacitor Cfinger is formed between finger 300 and top-level metallic M_top, secondary signal source, the first signal source add
The first electric capacity C1, the second electric capacity C2 are formed on a layers of metal M_a and respectively with top-level metallic M_top, a layers of metal M_a is
Any layer of metal of below top-level metallic M_top, forms the 3rd electric capacity C3, top layer gold between top-level metallic M_top and ground VSS
Reference capacitance Cref is formed between category M_top and a layers of metal M_a, the 3rd signal source is amplified by the 3rd switch SW3 with electric charge
The normal phase input end connection of device CA, the left side ground of second switch SW2, the right side of second switch SW2 is with charge amplifier CA's
Normal phase input end is connected, and the inverting input of charge amplifier CA is connected with top-level metallic M_top, and charge amplifier CA's is anti-phase
Input is connected with the left side of first switch SW1, and the right side of first switch SW1 is connected with the output end of charge amplifier CA, electricity
The output end of lotus amplifier CA is connected with a layers of metal M_a, the multiple correspondence of fingerprint detection unit 200 multiple charge amplifier CA
Output end, the output end of multiple charge amplifier CA as fingerprint detection circuit output end output signal.
The present invention is the fingerprint detection circuit of active/passive one, when the circuit is operated in active mode, it is necessary to according to
By an outside source, outside source output external analog signal VTX is coupled to inspection by fingerprint capacitor Cfinger
Slowdown monitoring circuit；For identical external analog signal VTX amplitudes, different fingerprint capacitor Cfinger can obtain different outputs
Voltage VCA；And when capacitive detection circuit is operated in passive type pattern, without outside source, fingerprint capacitor equivalent to ground connection,
Different output voltage VCA are obtained by being input into different signals；Thus by quantifying the value of VCA, fingerprint capacitor is quantified indirectly
The size of Cfinger, realizes fingerprint detection.Be combined for active and passive type structure by fingerprint detection circuit of the invention,
Make fingerprint detection circuit can carry out different designs using design according to different demands, and governor circuit sets according to different
Meter demand can be packaged into active or passive type scheme to the finger signal different with the input of fingerprint detection unit, greatly
The various costs such as design, checking, the stock of fingerprint detection chip are saved greatly.With reference to Fig. 2, Fig. 2 is a kind of fingerprint in the present invention
Detect circuit a specific embodiment circuit diagram, the present invention in, circuit have the initiative formula mode of operation when, outside source
The external analog signal VTX of output is added on finger, and in addition, outside source can also be using other side in the prior art
In formula input fingerprint detection circuit.
The present invention is realized using CMOS technology, but the invention is not restricted to CMOS technology, such as Bipolar techniques can also be real
The existing present invention.As shown in Fig. 2 M_top and M_a are respectively the top-level metallic and a layers of metal of CMOS technology, top-level metallic M_
Top is induction electrode, as a pole plate of fingerprint inductance capacitance, fingerprint capacitor Cfinger is formed with finger.Top-level metallic M_
3 parasitic capacitances, respectively the first electric capacity C1, the second electric capacity C2 and reference capacitance can be produced between top and a layers of metal M_a
Cref, wherein the first electric capacity C1 and the second electric capacity C2 contribute to adjust the output area of charge amplifier CA, the first electric capacity C1
The output voltage range of charge amplifier CA during for adjusting active；Electric charge amplifies when second electric capacity C2 is used for adjusting passive type
The output voltage range of device CA.Reference capacitance Cref is used to measure fingerprint capacitor Cfinger.A layers of metal M_a is according to design need
Ask, it can be the metal M_top-1 of ground floor below top-level metallic, below top-level metallic the second layer metal M_top-2, or
Person other metal levels.
Used as the further improvement of technical scheme, with reference to Fig. 2, Fig. 2 is an a kind of tool of fingerprint detection circuit in the present invention
Body embodiment circuit diagram, fingerprint detection circuit also includes that protective layer cover, protective layer cover are arranged at top-level metallic M_
On top, finger 300 forms fingerprint capacitor Cfinger by protective layer cover and top-level metallic M_top.Further, protect
Sheath includes coating, glass or ceramics, for protecting chip not to be damaged, protective layer cover directly can also be adhered into core
On piece；After finger 300 is pressed into the surface of protective layer cover, top-level metallic M_top forms fingerprint electricity with the surface of finger 300
Hold Cfinger.
It is a kind of fingerprint detection circuit in the present invention with reference to Fig. 1 and Fig. 2, Fig. 1 as the further improvement of technical scheme
One specific embodiment structural representation, Fig. 2 is an a kind of specific embodiment circuit diagram of fingerprint detection circuit in the present invention,
In the present embodiment, governor circuit 100 includes control circuit 101 and digital analog converter 102, and control circuit 101 is used to control
First switch SW1, second switch SW2, the on off state of the 3rd switch SW3 and output external analog signal VTX and control number
Word analog converter 102 exports the first analog signal VDAC1, the second analog signal VDAC2 and the 3rd analog signal VDAC3, number
Word analog converter 102 is used to export the first analog signal VDAC1, the second analog signal VDAC2 and the 3rd analog signal
VDAC3, controls the output end of circuit 101 to be connected with the input of digital analog converter 102, control circuit 101 output first
Clock signal S1, second clock signal S2 and the 3rd clock signal S3 are respectively used to control first switch SW1, second switch SW2
With the 3rd switch SW3.Digital analog converter (Digital to analog converter, english abbreviation：DAC it is) a kind of
The equipment for converting digital signals into analog signal (in the form of electric current, voltage or electric charge).In many digital display circuits (for example
Computer), signal is stored and transmitted in a digital manner, and such signal can be converted to simulation letter by digital analog converter
Number, so that they can be recognized by extraneous (people or other nonnumeric systems).
Used as the further improvement of technical scheme, with reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4, Fig. 1 is a kind of fingerprint inspection in the present invention
One specific embodiment structural representation of slowdown monitoring circuit, Fig. 2 is a kind of specific embodiment electricity of fingerprint detection circuit in the present invention
Road schematic diagram, Fig. 3 is a kind of active job control oscillogram of fingerprint detection circuit in the present invention, and Fig. 4 is one in the present invention
One specific embodiment schematic diagram of the active circuit of kind of fingerprint detection circuit, fingerprint detection circuit has the initiative formula mode of operation
When, it is necessary to outside source output external analog signal VTX, in the present embodiment, external analog signal VTX is exported to finger 300；
Preferably, the capacitance size of reference capacitance Cref and the first electric capacity C1 belongs to same magnitude, the electricity of reference capacitance Cref and first
The capacitance for holding C1 can belong to the capacitance phase of same magnitude, reference capacitance Cref and the first electric capacity C1 with equal or suitable
Difference is little, and such as the capacitance of reference capacitance Cref is 3FF, and the capacitance of the first electric capacity C1 is 4FF；The active of fingerprint detection circuit
Formula job control sequential is specially：
Second clock signal S1 is low level signal, i.e. SW2=0；3rd clock signal S3 is high level signal, i.e. SW3
=1；First analog signal VDAC1 is low level signal；Second analog signal VDAC2 is square-wave signal, the first clock signal S1
During for low level, the magnitude of voltage of the second analog signal VDAC2 is first voltage v1, when the first clock signal S1 is high level, the
The magnitude of voltage of two analog signal VDAC2 is second voltage v2, and V1 and V2 in Fig. 3 are relative values, and V1 may be bigger than V2；3rd mould
It is direct current signal to intend signal VDAC3；3rd analog signal VDAC3 only needs to voltage and keeps constant, the 3rd analog signal
The voltage swing of VDAC3 is by governor circuit control；External analog signal VTX and the first clock signal S1 is disjoint signals, outward
The low level voltage of portion analog signal VTX is 0, and the high level voltage of external analog signal VTX is external analog voltages vtx.
During with reference to Fig. 3 and Fig. 4, SW1=1, the charge discharge on reference capacitance Cref just no longer stores electric charge after terminating；
During SW1=0, external analog signal VTX is increased to vtx.When waveform according to Fig. 3 controls fingerprint detection circuit, fingerprint capacitor
The left end of Cfinger is charged to VTX, and the required quantity of electric charge is Q1=VTX*Cfinger, and these quantities of electric charge are from the first electricity
Hold C1 and reference capacitance Cref, wherein the quantity of electric charge that the first electric capacity C1 is provided is Q2=(v2-v1) * C1, reference capacitance Cref is carried
The quantity of electric charge of confession is Q3=(VCA-VDAC3) * Cref.Q1=Q2+Q3 is had according to law of conservation of charge, thus can be calculated
The value of the output voltage VCA of charge amplifier CA, i.e.,：
From above formula, the second analog signal VDAC2 and the first electric capacity C1 is used to adjust the scope of output voltage VCA, makes
Output voltage VCA is preferably quantified by analog-digital converter below.Wherein, VTX is the magnitude of voltage of external analog signal,
Cfinger is the capacitance of fingerprint capacitor, and C1 is the capacitance of the first electric capacity, the capacitance of electric capacity on the basis of Cref, and VDAC3 is
The magnitude of voltage of the 3rd analog signal.
It is a kind of fingerprint detection circuit in the present invention with reference to Fig. 5 and Fig. 6, Fig. 5 as the further improvement of technical scheme
The another specific embodiment structural representation of active circuit, Fig. 6 is a kind of active electric of fingerprint detection circuit in the present invention
The another specific embodiment circuit diagram on road, fingerprint detection circuit also includes active control circuit, outside source and master
The input connection of dynamic formula control circuit, the output end of active control circuit is connected with the ground of fingerprint detection circuit, for root
According to the voltage on the ground of external analog signal control fingerprint detection circuit, thus, fingerprint detection circuit treatment is by by external analog
Signal output to finger realized outside active circuit, can also be active to realize by increasing an active control circuit
Circuit, in the present embodiment, active control circuit is realized using an active control chip, in Fig. 6, active control core
The output end of piece is connected with the ground VSS of fingerprint detection circuit, and in the present embodiment, the output end of active control chip is schematically
The earth terminal of the 3rd electric capacity is connected, represents that the output end of active control chip is connected with the ground of fingerprint detection circuit, in addition, electric
Output end of the earth terminal of lotus amplifier CA also with active control chip is connected.
Further, it is a kind of active job control ripple of fingerprint detection circuit in the present invention with reference to Fig. 3 and Fig. 6, Fig. 3
Shape figure, Fig. 6 is a kind of another specific embodiment circuit diagram of the active circuit of fingerprint detection circuit in the present invention, this reality
Apply in example, the capacitance size of reference capacitance Cref and the first electric capacity C1 belongs to same magnitude；Fingerprint detection circuit it is active
Job control sequential is：
Second clock signal S1 is low level signal, i.e. SW2=0；3rd clock signal S3 is high level signal, i.e. SW3
=1；First analog signal VDAC1 is low level signal；Second analog signal VDAC2 is square-wave signal, the first clock signal S1
During for low level, the magnitude of voltage of the second analog signal VDAC2 is first voltage v1, when the first clock signal S1 is high level, the
The magnitude of voltage of two analog signal VDAC2 is second voltage v2, and V1 and V2 in Fig. 3 are relative values, and V1 may be bigger than V2；3rd mould
It is direct current signal to intend signal VDAC3；3rd analog signal VDAC3 only needs to voltage and keeps constant, the 3rd analog signal
The voltage swing of VDAC3 is by governor circuit control；In the present embodiment, outside source exports external analog signal VTX to actively
On formula control chip, external analog signal VTX and the first clock signal S1 is disjoint signals, and external analog signal VTX's is low
Level voltage is 0, and the high level voltage of external analog signal VTX is external analog voltages vtx；The power supply of active control chip
Voltage is the first supply voltage VDDHV, and the output voltage of active control chip is ground voltage VGND；External analog signal
When the low level voltage of VTX is 0, the ground voltage VGND of active control chip output is 0, controls the ground of fingerprint detection circuit
Voltage be 0；When the high level voltage of external analog signal VTX is vtx, the ground voltage VGND of active control chip output
It is not 0, it is ground voltage VGND, now, ground voltage that active control chip controls the voltage on the ground of fingerprint detection circuit
VGND can be positive voltage, or negative voltage, and voltage swing is controlled by active control chip.Further, electric charge is put
The output voltage of the output end of big device is：
Wherein, VDDHV is the magnitude of voltage of the first supply voltage, and Cfinger is the capacitance of fingerprint capacitor, and C1 is the first electricity
The capacitance of appearance, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
It is a kind of fingerprint detection circuit in the present invention with reference to Fig. 7 and Fig. 8, Fig. 7 as the further improvement of technical scheme
Passive type job control oscillogram, Fig. 8 is an a kind of specific embodiment of the passive type circuit of fingerprint detection circuit in the present invention
Schematic diagram, now, circuit need not be input into external analog signal, in the present embodiment, it is preferable that reference capacitance Cref and the first electric capacity
The capacitance size of C1 belongs to same magnitude, and the capacitance size of the second electric capacity C2 and the 3rd electric capacity C3 belongs to same magnitude, this
In invention, the capacitance size of the second electric capacity C2 and the 3rd electric capacity C3 is arranged on tens flying methods or so；Specific fingerprint detection electricity
The passive type job control sequential on road is：
First clock signal S1 and second clock signal S2 is identical clock signal, during the first clock signal S1 and the 3rd
Clock signal S3 is non-overlapping clock signal；
First analog signal VDAC1 and the second analog signal VDAC2 is square-wave signal, and the first clock signal S1 is high level
When, the magnitude of voltage of the second analog signal VDAC2 is the 5th voltage for the magnitude of voltage of tertiary voltage v3, the first analog signal VDAC1
v5；When first clock signal S1 is low level, the magnitude of voltage of the second analog signal VDAC2 is the 4th voltage v4, the first simulation letter
The magnitude of voltage of number VDAC1 is the 6th voltage v6, and V3 and V4 are relative values in Fig. 7, and V3 may be bigger than V4, and V5 and V6 are phases in Fig. 7
To value, V5 may be bigger than V6；3rd analog signal VDAC3 is low level signal or high level signal, similarly, the 3rd simulation
Signal VDAC3 is direct current signal；3rd analog signal VDAC3 only needs to voltage and keeps constant.
During with reference to Fig. 7 and Fig. 8, SW1=1, the charge discharge on reference capacitance Cref just no longer stores electric charge, A after terminating
The voltage of point, B points and charge amplifier VCA these three nodes is all 0；During SW3=1, A points are changed into VDAC3, and B points are due to electric charge
The effect of amplifier CA, is also changed into VDAC3, thus fingerprint capacitor Cfinger can be charged to VDAC3 from 0.
In the above-mentioned course of work, the right-hand member of fingerprint capacitor Cfinger is charged to VDAC3, and the required quantity of electric charge is Q1=
The upper end of VDAC3*Cfinger, the 3rd electric capacity C3 is also charged to VDAC3, and the required quantity of electric charge is Q2=VDAC3*Cp, and Q1 and
Q2 is all from the first electric capacity C1, the second electric capacity C2 and reference capacitance Cref, wherein the quantity of electric charge that the first electric capacity C1 is provided is Q3=
(v4-v3) quantity of electric charge that * C1, the second electric capacity C2 are provided is Q4=(v6-v5) * C2, and the quantity of electric charge that reference capacitance Cref is provided is
Q5=(VCA-VDAC3) * Cref.Q1+Q2=Q3+Q4+Q5 is had according to law of conservation of charge, thus electric charge can be calculated and put
The value of the output voltage VCA of big device CA, i.e.,：
From above formula, the first analog signal VDAC1, the second analog signal VDAC2, the first electric capacity C1 and the second electric capacity C2
Scope for adjusting output voltage VCA, makes output voltage VCA preferably be quantified by ADC below.Wherein, Cfinger is finger
The capacitance of line electric capacity, C3 is the capacitance of the 3rd electric capacity, and C1 is the capacitance of the first electric capacity, and C2 is the electric capacity of the second electric capacity
Value, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
A kind of fingerprint detection sensor, including above-mentioned fingerprint detection circuit, as long as one chips of design, it is possible to realize
Active and passive type, therefore the design cycle of fingerprint detection sensor is short and expense is few.
Above is preferable implementation of the invention is illustrated, but the invention is not limited to the implementation
Example, those of ordinary skill in the art can also make a variety of equivalent variations or replace on the premise of without prejudice to spirit of the invention
Change, these equivalent deformations or replacement are all contained in the application claim limited range.
Claims (12)
1. a kind of fingerprint detection circuit, it is characterised in that including at least two metal layers, governor circuit, outside source, first
Signal source, secondary signal source, the 3rd signal source and multiple fingerprint detection unit, the fingerprint detection unit include first switch,
Second switch, the 3rd switch and charge amplifier, the governor circuit be used for export the first clock signal, second clock signal,
3rd clock signal, for controlling the on off state of first switch, second switch, third switch respectively, and exports external analog
Signal, the first analog signal, the second analog signal, the 3rd analog signal, for respectively as outside source, the first signal
Source, secondary signal source, the 3rd signal source；
Fingerprint capacitor is formed between the finger and top-level metallic, the secondary signal source, the first signal source are added in a layers of metal
Go up and form the first electric capacity, the second electric capacity with top-level metallic respectively, a layers of metal is any a layer below top-level metallic
Metal, forms the 3rd electric capacity between the top-level metallic and ground, benchmark electricity is formed between the top-level metallic and a layers of metal
Hold, the 3rd signal source is connected by the 3rd switch with the normal phase input end of charge amplifier, the left side of the second switch
Ground connection, the right side of the second switch is connected with the normal phase input end of charge amplifier, the anti-phase input of the charge amplifier
End is connected with top-level metallic, and the inverting input of the charge amplifier is connected with the left side of first switch, the first switch
Right side be connected with the output end of charge amplifier, the output end of the charge amplifier is connected with a layers of metal, the multiple
The output end of charge amplifier as fingerprint detection circuit output end output signal.
2. fingerprint detection circuit according to claim 1, it is characterised in that the fingerprint detection circuit also includes protection
Layer, the protective layer is arranged on top-level metallic, and the finger forms fingerprint capacitor by protective layer with top-level metallic.
3. fingerprint detection circuit according to claim 1, it is characterised in that the governor circuit includes control circuit sum
Word analog converter, the control circuit is used to control outside the on off state of first switch, second switch, third switch and output
Portion's analog signal and control digital analog converter export the first analog signal, the second analog signal and the 3rd analog signal,
The digital analog converter is used to export the first analog signal, the second analog signal and the 3rd analog signal, the control electricity
The output end on road is connected with the input of digital analog converter.
4. fingerprint detection circuit according to claim 2, it is characterised in that the protective layer includes coating, glass or pottery
Porcelain.
5. the fingerprint detection circuit according to any one of Claims 1-4, it is characterised in that the fingerprint detection circuit
Active job control sequential is：
The second clock signal is low level signal；3rd clock signal is high level signal；
First analog signal is low level signal；When first clock signal is low level, second analog signal
Magnitude of voltage be first voltage v1, when first clock signal is high level, the magnitude of voltage of second analog signal is the
Two voltage v2；3rd analog signal is direct current signal；
On outside source output external analog signal to the finger, the external analog signal is non-with the first clock signal
Overlap signal, the low level voltage of the external analog signal is 0, and the high level voltage of the external analog signal is outside mould
Intend voltage vtx.
6. the fingerprint detection circuit according to any one of Claims 1-4, it is characterised in that the fingerprint detection circuit is also
Including active control circuit, the outside source is connected with the input of active control circuit, the active control
The output end of circuit is connected with the ground of fingerprint detection circuit, for the ground according to external analog signal control fingerprint detection circuit
Voltage.
7. fingerprint detection circuit according to claim 6, it is characterised in that the active work of the fingerprint detection circuit
Control sequential is：
The second clock signal is low level signal；3rd clock signal is high level signal；
First analog signal is low level signal；When first clock signal is low level, second analog signal
Magnitude of voltage be first voltage v1, when first clock signal is high level, the magnitude of voltage of second analog signal is the
Two voltage v2；3rd analog signal is direct current signal；
The outside source exports external analog signal to active control circuit, the external analog signal and when first
Clock signal is disjoint signals, and the low level voltage of the external analog signal is 0, the high level electricity of the external analog signal
It is external analog voltages vtx to press；The active supply voltage for controlling circuit is the first supply voltage VDDHV, the active
It is ground voltage VGND that formula controls the output voltage of circuit；When the low level voltage of the external analog signal is 0, active control
The ground voltage VGND of circuit output processed is 0, and the voltage for controlling the ground of fingerprint detection circuit is 0；The external analog signal
When high level voltage is vtx, the ground voltage VGND of active control circuit output is not 0, and active control circuit control refers to
The voltage on the ground of line detection circuit is ground voltage VGND.
8. the fingerprint detection circuit according to any one of Claims 1-4, it is characterised in that the fingerprint detection circuit
Passive type job control sequential is：
First clock signal and second clock signal are identical clock signal, first clock signal and the 3rd clock
Signal is non-overlapping clock signal；
When first clock signal is high level, the magnitude of voltage of second analog signal is tertiary voltage v3, described first
The magnitude of voltage of analog signal is the 5th voltage v5；When first clock signal is low level, the electricity of second analog signal
Pressure value is the 4th voltage v4, and the magnitude of voltage of first analog signal is the 6th voltage v6；3rd analog signal is low electricity
Ordinary mail number or high level signal.
9. fingerprint detection circuit according to claim 5, it is characterised in that the output of the output end of the charge amplifier
Voltage is：
Wherein, VTX is the magnitude of voltage of external analog signal, and Cfinger is the capacitance of fingerprint capacitor, and C1 is the electricity of the first electric capacity
Capacitance, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
10. fingerprint detection circuit according to claim 7, it is characterised in that the output end of the charge amplifier it is defeated
Going out voltage is：
Wherein, VDDHV is the magnitude of voltage of the first supply voltage, and Cfinger is the capacitance of fingerprint capacitor, and C1 is the first electric capacity
Capacitance, the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
11. fingerprint detection circuits according to claim 8, it is characterised in that the output end of the charge amplifier it is defeated
Going out voltage is：
Wherein, Cfinger is the capacitance of fingerprint capacitor, and C3 is the capacitance of the 3rd electric capacity, and C1 is the capacitance of the first electric capacity,
C2 is the capacitance of the second electric capacity, and the capacitance of electric capacity on the basis of Cref, VDAC3 is the magnitude of voltage of the 3rd analog signal.
12. a kind of fingerprint detection sensors, it is characterised in that including the fingerprint detection electricity described in any one of claim 1 to 11
Road.
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| CN201611262306.XA CN106778672B (en) | 2016-12-30 | 2016-12-30 | Fingerprint detection circuit and fingerprint detection sensor |
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| CN108664955A (en) * | 2018-06-14 | 2018-10-16 | 上海思立微电子科技有限公司 | Fingerprint identification device |
| CN110084082A (en) * | 2018-01-26 | 2019-08-02 | 比亚迪股份有限公司 | A kind of electronic equipment, fingerprint identification device and its finger touch detection circuit |
| WO2022109999A1 (en) * | 2020-11-27 | 2022-06-02 | 敦泰电子（深圳）有限公司 | Capacitive fingerprint recognition system, electronic device and fingerprint recognition method |
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| CN105138986A (en) * | 2015-08-25 | 2015-12-09 | 敦泰电子有限公司 | Fingerprint detection circuit, fingerprint detection device and touch panel |
| CN105447438A (en) * | 2015-02-13 | 2016-03-30 | 比亚迪股份有限公司 | Fingerprint detection circuit and electronic device |
| CN105512650A (en) * | 2016-01-26 | 2016-04-20 | 湖南融创微电子有限公司 | Capacitive fingerprint detection circuit, sensor and device |
| CN205247408U (en) * | 2015-12-07 | 2016-05-18 | 湖南融创微电子有限公司 | Fingerprint detection circuit and fingerprint sensor |
| CN205540784U (en) * | 2016-01-26 | 2016-08-31 | 湖南融创微电子有限公司 | Capacitanc fingerprint detection circuit, sensor and equipment |
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| CN105447438A (en) * | 2015-02-13 | 2016-03-30 | 比亚迪股份有限公司 | Fingerprint detection circuit and electronic device |
| CN105138986A (en) * | 2015-08-25 | 2015-12-09 | 敦泰电子有限公司 | Fingerprint detection circuit, fingerprint detection device and touch panel |
| CN205247408U (en) * | 2015-12-07 | 2016-05-18 | 湖南融创微电子有限公司 | Fingerprint detection circuit and fingerprint sensor |
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| CN110084082A (en) * | 2018-01-26 | 2019-08-02 | 比亚迪股份有限公司 | A kind of electronic equipment, fingerprint identification device and its finger touch detection circuit |
| CN108664955A (en) * | 2018-06-14 | 2018-10-16 | 上海思立微电子科技有限公司 | Fingerprint identification device |
| CN108664955B (en) * | 2018-06-14 | 2024-01-12 | 上海思立微电子科技有限公司 | Fingerprint identification device |
| WO2022109999A1 (en) * | 2020-11-27 | 2022-06-02 | 敦泰电子（深圳）有限公司 | Capacitive fingerprint recognition system, electronic device and fingerprint recognition method |
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