CN109120834A - Image sensor pixel circuit and its working method - Google Patents
Image sensor pixel circuit and its working method Download PDFInfo
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- CN109120834A CN109120834A CN201811286237.5A CN201811286237A CN109120834A CN 109120834 A CN109120834 A CN 109120834A CN 201811286237 A CN201811286237 A CN 201811286237A CN 109120834 A CN109120834 A CN 109120834A
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- 238000009792 diffusion process Methods 0.000 claims abstract description 84
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- 230000005611 electricity Effects 0.000 claims description 9
- 239000013078 crystal Substances 0.000 claims description 7
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- 230000003071 parasitic effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 4
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/50—Constructional details
- H04N23/54—Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/71—Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
- H04N25/75—Circuitry for providing, modifying or processing image signals from the pixel array
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- Transforming Light Signals Into Electric Signals (AREA)
- Solid State Image Pick-Up Elements (AREA)
Abstract
A kind of image sensor pixel circuit and its working method, circuit include: key light electric diode；Attached photodiode；First transmission transistor, the source level of the first transmission transistor is connected respectively the first positive connecting pin and connects with drain electrode spreads point with the first floating；Second transmission transistor, the source level of the second transmission transistor connect attached photodiode, and the drain electrode of the second transmission transistor connects the first floating diffusion point or the second floating spreads point；Extra transistor, the source electrode and drain electrode of extra transistor is connected respectively the first floating diffusion point and the second floating spreads point；First reset transistor, the drain electrode of the first reset transistor and source level are connected respectively the first power supply line and the second floating diffusion point；Second reset transistor, the source level of the second reset transistor and drain electrode are connected respectively the first positive connecting pin and second source line；Connect the capacitor of the second floating diffusion point；Column sense line.The performance of described image sensor pixel circuit improves.
Description
Technical field
The present invention relates to field of semiconductor manufacture more particularly to a kind of image sensor pixel circuit and its working methods.
Background technique
Imaging sensor is a kind of semiconductor devices for converting optical signal into electric signal.
Imaging sensor is divided into complementary metal oxide (CMOS) imaging sensor and charge-coupled device (CCD) image passes
Sensor.Wherein cmos image sensor have simple process, be easy to integrated other devices, small in size, light-weight, small power consumption and at
This low advantage.Therefore, with the development of image sensing technology, cmos image sensor replaces ccd image to pass more and more
Sensor is applied in each electronic product.Currently, cmos image sensor has been widely used for static digital camera, number is taken the photograph
Camera, medical photographic device and automobile-used photographic device etc..
However, the performance of existing imaging sensor is to be improved.
Summary of the invention
Problems solved by the invention is to provide a kind of image sensor pixel circuit and its working method, to improve image biography
The performance of sensor pixel circuit.
To solve the above problems, the present invention provides a kind of image sensor pixel circuit, comprising: key light electric diode, institute
Key light electric diode is stated with the first positive connecting pin；Attached photodiode；First transmission transistor, the first transmission transistor
Source level is connect with the first positive connecting pin, and the drain electrode of the first transmission transistor connects the first floating and spreads point；Second transmission crystal
Pipe, the source level of the second transmission transistor are connect with the attached photodiode, and the drain electrode connection first of the second transmission transistor is floating
Sky diffusion point or the second floating spread point；Extra transistor, the source electrode of the extra transistor connect the first floating and spread point, institute
The drain electrode for stating extra transistor connects the second floating diffusion point；First reset transistor, the drain electrode of the first reset transistor and the
The connection of one power supply line, the source level of the first reset transistor connect the second floating and spread point；Second reset transistor, second resets crystalline substance
The source level of body pipe is connect with the first positive connecting pin, and the drain electrode of the second reset transistor is connect with second source line；Capacitor, it is described
Capacitor and the diffusion point connection of the second floating；Column sense line, the column sense line are adapted to read out the current potential letter of the first floating diffusion point
Breath.
Optionally, the photosensitive area of the key light electric diode is greater than the photosensitive area of the attached photodiode.
Optionally, the photosensitive area of the attached photodiode be the key light electric diode photosensitive area 5%~
20%.
Optionally, further includes: follow transistor, the grid of the follow transistor and the first floating diffusion point company
It connects, the drain electrode of the follow transistor is connect with the first power supply line；Selection transistor, the drain electrode of the selection transistor and institute
The source electrode connection of follow transistor is stated, the source electrode of the selection transistor is connect with the column sense line.
Optionally, the current potential of second source line is identical as the current potential of the first power supply line；Alternatively, the current potential of second source line with
The current potential of first power supply line is different.
Optionally, the capacitor has opposite first end and second end, first end and the diffusion point connection of the second floating, the
Two ends ground connection.
Optionally, the key light electric diode also has the first Opposite direction connection end, the first Opposite direction connection end ground connection；It is described attached
Photodiode has the second positive connecting pin and the second Opposite direction connection end, and the second positive connecting pin connects the second transmission transistor
Source level, the second Opposite direction connection end ground connection.
The present invention also provides a kind of working methods of image sensor pixel circuit, comprising: provides above-mentioned any one
Image sensor pixel circuit；Carry out main exposure sequential step, in main exposure sequential step, the first reset transistor, second
Reset transistor, the first transmission transistor and the second transmission transistor are in off-state, and the extra transistor is in and leads
Logical state；After carrying out main exposure sequential step, main readout sequence step is carried out, in main readout sequence step, second resets crystalline substance
Body pipe and the second transmission transistor are in off-state, and main readout sequence step includes: to be in disconnect shape in extra transistor
Under state, first transmission transistor is connected, so that the charge in key light electric diode is spread point progress first to the first floating and fills
Electricity；After carrying out the first charging, in the case where extra transistor is in an off state, electricity of the column sense line to the first floating diffusion point
Position information carries out the first signal data acquisition；After carrying out the first signal data acquisition, in the case where extra transistor is in the conductive state,
The first transmission transistor is connected, the charge in key light electric diode is made to spread point and the diffusion point progress of the second floating to the first floating
Second charging；After carrying out the second charging, in the case where extra transistor is in the conductive state, the column sense line spreads the first floating
The electrical potential information of point carries out the acquisition of second signal data；After carrying out main readout sequence step, it is extended exposure time series step,
In extended exposure sequential step, second reset transistor and extra transistor are on state, and first resets crystal
Pipe, the first transmission transistor and the second transmission transistor are in off-state；After being extended exposure time series step, expanded
Sequential step is read out, in extension readout sequence step, the second reset transistor and extra transistor are on state,
First transmission transistor is in an off state, and the extension readout sequence step includes: the second transmission transistor of conducting, is made described
Charge in attached photodiode spreads point to the first floating and the second floating diffusion point carries out third charging；Carry out third charging
Afterwards, the column sense line carries out third signal data acquisition to the electrical potential information of the first floating diffusion point.
Optionally, the termination moment acquired in initial time to the second signal data of main readout sequence step, described
One reset transistor is in an off state.
Optionally, the main readout sequence step further include: carry out first charging before, the extra transistor,
First reset transistor and the first transmission transistor are in an off state down, electricity of the column sense line to the first floating diffusion point
Position information carries out the first reference data acquisition；The data collected according to the first reference data are obtained with the first signal data acquisition
The difference of the data arrived obtains the first useful signal data.
Optionally, the main readout sequence step further include: after carrying out the acquisition of second signal data, carry out master reset behaviour
Make, in master reset operation, the first reset transistor and extra transistor are in the conductive state, and the first transmission transistor is in disconnected
Open state；After carrying out master reset operation, it is in an off state in the first reset transistor and the first transmission transistor and adds crystalline substance
Under body pipe is in the conductive state, the column sense line carries out the second reference data to the electrical potential information of the first floating diffusion point and adopts
Collection；The difference for the data that the data and second signal data collected according to the second reference data collect, obtaining second has
Imitate signal data.
Optionally, the extension readout sequence step further include: after carrying out third signal data acquisition, be extended reset
Operation resets in operation in extension, and the first reset transistor is in the conductive state, and the second transmission transistor is in an off state；
After being extended reset operation, it is in an off state in the first reset transistor and the second transmission transistor is in an off state
Under, the column sense line carries out the acquisition of third reference data to the electrical potential information of the first floating diffusion point；According to third base value
According to the difference for the data that the data and third signal data acquisition that collect obtain, third useful signal data are obtained.
Optionally, further includes: after carrying out main readout sequence step, and before being extended exposure time series step,
It is extended emptying step；In extension emptying step, the first reset transistor and the second reset transistor are in the conductive state,
First transmission transistor is in an off state, and the second transmission transistor is in the conductive state, and extra transistor is in the conductive state,
Selection transistor is in an off state.
Compared with prior art, technical solution of the present invention has the advantage that
In the working method for the image sensor pixel circuit that technical solution of the present invention provides, main exposure timing step is being carried out
In rapid, the extra transistor is in the conductive state, therefore works as key light electric diode in the case where overexposure, key light electric diode
In light induced electron can be spilled over to by the first transmission transistor the first floating diffusion point and the second floating spread point.It is being led
In exposure time series step and main readout sequence step, the second reset transistor is in an off state, therefore in key light electric diode
Light induced electron will not be transferred to second source line.Due in carrying out main exposure sequential step and main readout sequence step,
Second transmission transistor is in an off state, and the area of attached photodiode be less than key light electric diode area, therefore
It carries out in main exposure sequential step and main readout sequence step, the light induced electron in attached photodiode is not overflowed to first and floated
Sky diffusion point.The lower light induced electron turn for carrying out the first charging, making in key light electric diode is in an off state in extra transistor
Move to the first floating diffusion point.Since the full trap capacitor of the first floating diffusion point is smaller, the first signal data acquisition is obtained
Data for characterizing the information of image in the dark.In extra transistor lower the second charging of progress in the conductive state, second fills
Electricity makes the light induced electron in key light electric diode be transferred to the first floating diffusion point and the second floating diffusion point, is mainly floated by first
The parasitic capacitance of sky diffusion point and the capacitor store the light induced electron in key light electric diode.Since the first floating is spread
The full trap capacitor of point and the capacitor jointly is greater than the full trap capacitor of the first floating diffusion point, therefore exposes in key light electric diode
In the case where, the parasitic capacitance of the first floating diffusion point and the capacitor have enough capacitor spaces to store next autonomous electric diode
The light induced electron of generation, therefore the brightness of image that the data that collect of second signal data can characterize is greater than the first signal data
Collect the brightness of image that data can characterize.
In being extended exposure time series step, the second reset transistor is in the conductive state, therefore second resets crystal
Light induced electron in key light electric diode can be transferred to second source line by pipe.In being extended exposure time series step, institute
It is in the conductive state to state extra transistor, then the light when attached photodiode in the case where overexposure, in attached photodiode
Raw electrons are spilled over to the first floating diffusion point and the second floating diffusion point by the second transmission transistor, mainly by capacitor and the
The parasitic capacitance of one floating diffusion point stores the light induced electron overflowed from attached photodiode.The extension readout sequence step
Include: the second transmission transistor of conducting, the charge in the attached photodiode is made to spread point and the second floating to the first floating
Diffusion point carries out third charging, and third charging makes the light induced electron of the attached photodiode storage be transferred to the diffusion of the first floating
Point and the second floating spread point.Since the area of attached photodiode is less than key light electric diode, in attached photodiode
In the case where overexposure, the light induced electron generated in the attached photodiode is less, therefore the parasitism electricity of the first floating diffusion point
Hold and the capacitor there are enough capacitor spaces to store the light induced electron generated from attached photodiode.So third signal number
The brightness of image that can be characterized according to the data collected is greater than second signal data and collects the brightness of image that data can characterize,
Dynamic range is improved in this way.
Detailed description of the invention
Fig. 1 is a kind of schematic diagram of image sensor pixel circuit；
Fig. 2 is the schematic diagram of image sensor pixel circuit in one embodiment of the invention；
Fig. 3 is the flow chart of image sensor pixel circuit working method in one embodiment of the invention；
Fig. 4 is the timing diagram that image sensor pixel circuit works in one embodiment of the invention；
Fig. 5 is the schematic diagram of image sensor pixel circuit in another embodiment of the present invention.
Specific embodiment
As described in background, the performance for the image sensor pixel circuit that the prior art is formed is poor.
A kind of image sensor pixel circuit, referring to FIG. 1, including: photodiode；Transmission transistor, the transmission
Transistor PtxSource level connect with the positive connecting pin of the photodiode；First floating spreads point sfd, the diffusion of the first floating
Point sfd and transmission transistor PtxDrain electrode connection；Extra transistor Pss, extra transistor PssSource electrode and the first floating spread point
Sfd connection；Second floating spreads point lfd, and the second floating spreads point lfd and extra transistor PssDrain electrode connection；Reset crystal
Pipe Prst, reset transistor PrstDrain electrode connect with power supply line vdd, reset transistor PrstSource electrode and the second floating spread point
Lfd connection；Capacitor C, one end of capacitor C are connect with the second floating diffusion point lfd, and the other end of capacitor C is connect with ground wire；Source with
With transistor Psf, follow transistor PsfGrid and the first floating diffusion point sfd connect, the follow transistor Psf's
Drain electrode is connect with power supply line vdd；Row selecting transistor Psel, the row selecting transistor PselDrain electrode and the source follow crystal
Pipe PsfSource electrode connection, the row selecting transistor PselSource electrode connect with the column sense line bL.
For the image sensor pixel circuit in Fig. 1, the time of each exposed frame is identical, and when exposure use length exposure
Between, stroboscopic phenomenon is overcome in this way.
The information of dark place is first read out according to timing for the image sensor pixel circuit in Fig. 1, which is the
One data, specifically, spreading point in the first floating after the photoelectron of photodiode is transferred on the first floating diffusion point sfd
Sfd generates voltage change, and the current potential that the first floating spreads point sfd passes through row selecting transistor PselWith follow transistor PsfQuilt
It reads, obtains the first data；According to timing, the information at bright place is read, which is the second data, specifically, photodiode
Photoelectron pass through transmission transistor PtxWith extra transistor PssIt is transferred to the second floating diffusion point lfd and the diffusion of the first floating
It is corresponding from two pole of photoelectricity mainly to store the second data by the parasitic capacitance of capacitor C and the first floating diffusion point sfd by point sfd
The photoelectron of pipe generates voltage change in the first floating diffusion point sfd, and the current potential that the first floating spreads point sfd passes through row selection
Transistor PselWith follow transistor PsfIt is read, obtains the second data.By melting to the first data and the second data
It closes, obtains a picture image, the dynamic range of the picture image is higher.
Image sensor pixel circuit in Fig. 1, when the parasitism electricity of the capacitance of capacitor C and the first floating diffusion point sfd
When the ratio of appearance is 16~32, the dynamic range of described image sensor pixel circuit can reach 90dB to 100dB.
However, in practice, the size ratio of the capacitor of capacitor C and the first floating diffusion point can not get very high number
Value, reason includes: the limited area that capacitor C is occupied since capacitor C makes in one pixel, therefore capacitor C can not accomplish very
Greatly；If capacitor C and the size ratio of the capacitor of the first floating diffusion point are very big, such as reach 100, then the first data and the second number
According to transitional region signal-to-noise ratio it is too small, image quality decrease after leading to the second data and the first data fusion.
To sum up, since capacitor C and the raising of the size ratio of the capacitor of the first floating diffusion point are restricted, image
The raising of the dynamic range of sensor pixel circuits is restricted.It needs to obtain in practical application more than 120dB dynamic range
Image sensor pixel circuit, such as: when in tunnel environment, round-the-clock monitoring environment or automotive field, need superelevation dynamic
The image sensor pixel circuit of range.
On this basis, the present invention provides a kind of image sensor pixel circuit, comprising: key light electric diode, key light electricity
Diode has the first positive connecting pin；Attached photodiode；First transmission transistor, the source level of the first transmission transistor and
One positive connecting pin connection, the drain electrode of the first transmission transistor connect the first floating and spread point；Second transmission transistor, second passes
The source level of defeated transistor is connect with attached photodiode, and the drain electrode of the second transmission transistor connects the first floating diffusion point or second
Floating spreads point；Extra transistor, first floating that the source electrode of extra transistor connects spread point, the drain electrode connection of extra transistor
Second floating spreads point；First reset transistor, the drain electrode of the first reset transistor are connect with the first power supply line, and first resets crystalline substance
The source level of body pipe connects the second floating and spreads point；Second reset transistor, the source level of the second reset transistor and the first forward direction are even
End connection is connect, the drain electrode of the second reset transistor is connect with second source line；Capacitor, capacitor and the diffusion point connection of the second floating；
Column sense line, column sense line are adapted to read out the electrical potential information of the first floating diffusion point.The property of described image sensor pixel circuit
It can be improved.
To make the above purposes, features and advantages of the invention more obvious and understandable, with reference to the accompanying drawing to the present invention
Specific embodiment be described in detail.
The embodiment of the present invention provides a kind of image sensor pixel circuit, referring to FIG. 2, including:
Key light electric diode 200, the key light electric diode 200 have the first positive connecting pin；
Attached photodiode 210；
First transmission transistor 220, the source level of the first transmission transistor 220 are connect with the first positive connecting pin, and first passes
The drain electrode of defeated transistor 220 connects the first floating and spreads point FD1；
Second transmission transistor 230, the source level of the second transmission transistor 230 are connect with the attached photodiode 210, the
The drain electrode of two transmission transistors 230 connects the first floating and spreads point FD1；
Extra transistor 240, the source electrode of the extra transistor 240 connect the first floating and spread point FD1, the additional crystalline substance
The drain electrode of body pipe 240 connects the second floating and spreads point FD2；
First reset transistor 250, the drain electrode of the first reset transistor 250 are connect with the first power supply line L_VDD1, and first
The source level of reset transistor 250 connects the second floating and spreads point FD2；
Second reset transistor 260, the source level of the second reset transistor 260 are connect with the first positive connecting pin, and second is multiple
The drain electrode of bit transistor 260 is connect with second source line L_VDD2；
Capacitor 270, the capacitor 270 are connect with the second floating diffusion point FD2；
Column sense line BL, the column sense line BL are adapted to read out the electrical potential information of the first floating diffusion point FD1.
The photosensitive area of the key light electric diode 200 is greater than the photosensitive area of the attached photodiode 210.Identical
Time for exposure in, the light that is generated far more than attached photodiode 210 of quantity for the light induced electron that key light electric diode 200 generates
The quantity of raw electronics.
In one embodiment, the photosensitive area of the attached photodiode 210 is the sense of the key light electric diode 200
The 5%~20% of light area.
The key light electric diode 200 also has the first Opposite direction connection end, the first Opposite direction connection end ground connection.
The attached photodiode 210 has the second positive connecting pin and the second Opposite direction connection end, the second positive connecting pin
Connect the source level of the second transmission transistor 230, the second Opposite direction connection end ground connection.
The capacitor 270 has opposite first end and second end, and first end is connect with the second floating diffusion point FD2, the
Two ends ground connection.
Described image sensor pixel circuit further include: follow transistor 280, the grid of the follow transistor 280
Pole is connect with the first floating diffusion point FD1, and the drain electrode of the follow transistor 280 is connect with the first power supply line L_VDD1；Choosing
Transistor 290 is selected, the drain electrode of the selection transistor 290 is connect with the source electrode of the follow transistor 280, and the selection is brilliant
The source electrode of body pipe 290 is connect with the column sense line BL.
In the present embodiment, the capacitance of capacitor 270 and the requirement of the ratio of the capacitor of the first floating diffusion point FD1 are lower,
The area that capacitor 270 occupies is smaller, and capacitor 270 is easy to production in one pixel, secondly, being conducive to effectively believe subsequent second
Image after the fusion of number and the first useful signal data, the second useful signal data and the first useful signal data fusion
Quality is preferable.
In the present embodiment, the ratio of the parasitic capacitance size of the size of capacitor 270 and the first floating diffusion point FD1 for 16~
40, such as 16~32.
The current potential VDD2 of second source line L_VDD2 is identical as the current potential VDD1 of the first power supply line L_VDD1；Alternatively, second
The current potential VDD2 of power supply line L_VDD2 is different from the current potential VDD1 of the first power supply line L_VDD1.
The present invention also provides a kind of working methods of image sensor pixel circuit, referring to FIG. 3, the following steps are included:
S01: provide above-mentioned image sensor pixel circuit (with reference to Fig. 2)；
S02: main exposure sequential step, in main exposure sequential step, first reset transistor 250, second are carried out
Reset transistor 260, the first transmission transistor 220 and the second transmission transistor 230 are in off-state, the additional transistor
Pipe 240 is in the conductive state；
S03: after carrying out main exposure sequential step, carrying out main readout sequence step, in main readout sequence step, described the
Two reset transistors 260 and the second transmission transistor 230 are in off-state, and main readout sequence step includes: in additional crystalline substance
Body pipe 240 is in an off state down, and first transmission transistor 220 is connected, and makes charge in key light electric diode 200 to the
One floating spreads FD1 point and carries out the first charging；It is described in the case where extra transistor 240 is in an off state after carrying out the first charging
Column sense line BL carries out the first signal data acquisition to the electrical potential information of the first floating diffusion point FD1；Carry out the first signal data
After acquisition, in the case where extra transistor 240 is in the conductive state, the first transmission transistor 220 is connected, makes key light electric diode 200
In charge to the first floating spread point FD1 and the second floating diffusion point FD2 progress second charge；After carrying out the second charging,
Under extra transistor 240 is in the conductive state, electrical potential information progress the of the column sense line BL to the first floating diffusion point FD1
The acquisition of binary signal data；
S04: after carrying out main readout sequence step, being extended exposure time series step, in extended exposure sequential step, institute
It states the second reset transistor 260 and extra transistor 240 is on state, the transmission of the first reset transistor 250, first is brilliant
Body pipe 220 and the second transmission transistor 230 are in off-state；
S05: after being extended exposure time series step, being extended readout sequence step, in extension readout sequence step,
Second reset transistor 260 and extra transistor 240 are on state, and the first transmission transistor 220 is in an off state,
The extension readout sequence step includes: the second transmission transistor 230 of conducting, makes the charge in the attached photodiode 210
Point FD1 is spread to the first floating and the second floating diffusion point FD2 carries out third charging；After carrying out third charging, the column are read
Line BL carries out third signal data acquisition to the electrical potential information of the first floating diffusion point FD1.
Fig. 4 is the timing diagram of image sensor pixel circuit in Fig. 2,
V (RSEL) is the clock signal of the grid of selection transistor 290, when V (RSEL) is high level, selection transistor
290 is in the conductive state, and when V (RSEL) is low level, selection transistor 290 is in an off state.
V (RST1) is the clock signal of the grid of the first reset transistor 250, and when V (RST1) is high level, first is multiple
Bit transistor 250 is in the conductive state, and when V (RST1) is low level, the first reset transistor 250 is in an off state.
V (RST2) is the clock signal of the grid of the second reset transistor 260, and when V (RST2) is high level, second is multiple
Bit transistor 260 is in the conductive state, and when V (RST2) is low level, the second reset transistor 260 is in an off state.
V (TG1) is the clock signal of the grid of the first transmission transistor 220, when V (TG1) is high level, the first transmission
Transistor 220 is in the conductive state, and when V (TG1) is low level, the first transmission transistor 220 is in an off state.
V (TG2) is the clock signal of the grid of the second transmission transistor 230, when V (TG2) is high level, the second transmission
Transistor 230 is in the conductive state, and when V (TG2) is low level, the second transmission transistor 230 is in an off state.
V (SS) is the clock signal of the grid of extra transistor 240, when V (SS) is high level, extra transistor 240
In the conductive state, when V (SS) is low level, extra transistor 240 is in an off state.
In the present embodiment, before carrying out main exposure sequential step, further includes: carry out main emptying step, empty step in master
In rapid, first reset transistor 250 is in the conductive state, and the second reset transistor 260 is in an off state, additional transistor
Pipe 240 is in the conductive state, and the first transmission transistor 220 and the second transmission transistor 230 are in the conductive state, selection transistor
290 are in an off state.The main emptying step makes in electronics and attached photodiode 210 in key light electric diode 200
Electronics empties.
In main exposure sequential step, first reset transistor 250, the transmission of the second reset transistor 260, first are brilliant
Body pipe 220 and the second transmission transistor 230 are in off-state, and the extra transistor 240 is in the conductive state, and selection is brilliant
Body pipe 290 is in an off state.
After carrying out main exposure sequential step, main readout sequence step is carried out, in main readout sequence step, described second is multiple
Bit transistor 260 and the second transmission transistor 230 are in off-state, and selection transistor 290 is in the conductive state.
The main readout sequence step includes: to pass in the extra transistor 240, the first reset transistor 250 and first
Defeated transistor 220 is in an off state down, and the column sense line BL carries out first to the electrical potential information of the first floating diffusion point FD1
Reference data acquisition.
At the termination moment that initial time to the first reference data of main readout sequence step acquires, first transmission is brilliant
Body pipe 220 and the first reset transistor 250 are constantly in off-state.
The main readout sequence step further include: after the acquisition of the first reference data, be in and disconnect in extra transistor 240
Under state, first transmission transistor 220 is connected, the charge in key light electric diode 200 is made to spread FD1 point to the first floating
Carry out the first charging；After carrying out the first charging, in the case where extra transistor 240 is in an off state, the column sense line BL is to the
The electrical potential information that one floating spreads point FD1 carries out the first signal data acquisition.
In the first charging, first transmission transistor 220 is in the conductive state, first reset transistor 250
It is in an off state, the extra transistor 240 is in an off state.
In the first signal data acquisition, extra transistor 240, the first transmission transistor 220 and the first reset transistor
250 are in an off state.
The difference for the data that the data and the first signal data acquisition collected according to the first reference data obtain obtains the
One useful signal data.
The main readout sequence step further include: after carrying out the first signal data acquisition, be in and lead in extra transistor 240
Under logical state, the first transmission transistor 220 is connected, make charge in key light electric diode 200 to the first floating diffusion point FD1 with
Second floating spreads point FD2 and carries out the second charging；After carrying out the second charging, in the case where extra transistor 240 is in the conductive state, institute
It states column sense line BL and the acquisition of second signal data is carried out to the electrical potential information of the first floating diffusion point FD1.
Crystalline substance is resetted at the termination moment that initial time to the second signal data of main readout sequence step acquire, described first
Body pipe 250 is in an off state.
In the second charging, the first reset transistor 250 is in an off state, and the first transmission transistor 220 is on
State, the extra transistor 240 are in the conductive state.
In the acquisition of second signal data, the first transmission transistor 220 is in an off state, and extra transistor 240 is in
On state, the first reset transistor 250 are in an off state.
The main readout sequence step further include: after carrying out the acquisition of second signal data, master reset operation is carried out, in master
It resets in operation, the first reset transistor 250 and extra transistor 240 are in the conductive state, and the first transmission transistor 220 is in
Off-state；After carrying out master reset operation, be in an off state in the first reset transistor 250 and the first transmission transistor 220,
And under extra transistor 240 is in the conductive state, the column sense line BL carries out the electrical potential information of the first floating diffusion point FD1
The acquisition of second reference data.
The difference for the data that the data and second signal data collected according to the second reference data collect obtains the
Two useful signal data.
After carrying out main readout sequence step, it is extended exposure time series step, in extended exposure sequential step, described
Two reset transistors 260 and extra transistor 240 are on state, the first reset transistor 250, the first transmission transistor
220 and second transmission transistor 230 be in off-state, selection transistor 290 is in an off state.
In the present embodiment, further includes: after carrying out main readout sequence step, and be extended exposure time series step it
Before, it is extended emptying step, in extension emptying step, the first reset transistor 250 and the second reset transistor 260 are in
On state, the first transmission transistor 220 are in an off state, and the second transmission transistor 230 is in the conductive state, additional transistor
Pipe 240 is in the conductive state, and selection transistor 290 is in an off state.The extension emptying step makes key light electric diode 200
In electronics and attached photodiode 210 in electronics empty.
After being extended exposure time series step, it is extended readout sequence step, in extension readout sequence step, second
Reset transistor 260 and extra transistor 240 are on state, and the first transmission transistor 220 is in an off state, described
Selection transistor 290 is in the conductive state.
The extension readout sequence step includes: the second transmission transistor 230 of conducting, makes the attached photodiode 210
In charge to the first floating spread point FD1 and the second floating diffusion point FD2 progress third charging；After carrying out third charging, institute
It states column sense line BL and third signal data acquisition is carried out to the electrical potential information of the first floating diffusion point FD1.
In third charging, the second transmission transistor 230 is in the conductive state, and the first reset transistor 250, which is in, to be disconnected
State.
In third signal data acquisition, the second transmission transistor 230 is in an off state, the first reset transistor 250
It is in an off state.
The extension readout sequence step further include: after carrying out third signal data acquisition, it is extended reset operation,
Extension resets in operation, and the first reset transistor 250 is in the conductive state, and the second transmission transistor 230 is in an off state；Into
After row extension resets operation, it is in an off state in the first reset transistor 250 and the second transmission transistor 230 is in and disconnects
Under state, the column sense line BL carries out the acquisition of third reference data to the electrical potential information of the first floating diffusion point FD1.
The difference for the data that the data and third signal data acquisition collected according to third reference data obtain obtains the
Three useful signal data.
The initial time of readout sequence step is being extended to the termination moment of third signal data acquisition, the first reset crystal
Pipe 250 is in an off state.
In the present embodiment, the total time of main exposure sequential step and the total time of extended exposure sequential step are equal.At it
In its embodiment, it is less than the total time of main exposure sequential step the total time of extended exposure sequential step.
In the present embodiment, since in being extended exposure time series step, the second reset transistor 260 is on shape
State, therefore the light induced electron in key light electric diode 200 can be transferred to second source line L_ by the second reset transistor 260
VDD2.In being extended exposure time series step, the extra transistor 240 is in the conductive state, then when attached two pole of photoelectricity
In the case where overexposure, 210 light induced electron can be spilled over to pipe 210 by the second transmission transistor 230 in attached photodiode
First floating spreads point FD1 and the second floating spreads point FD2, mainly by the parasitism electricity of capacitor 270 and the first floating diffusion point FD1
Store the light induced electron that storage is overflowed from attached photodiode 210.The extension readout sequence step includes: the second transmission of conducting
Transistor 230 makes the charge in the attached photodiode 210 spread point FD1 and the second floating diffusion point FD2 to the first floating
Third charging is carried out, the light induced electron that third charging stores the attached photodiode 210 is transferred to the first floating diffusion point
FD1 and the second floating spread point FD2.Since the area of attached photodiode 210 is less than key light electric diode 200, attached
In the case where 210 overexposure of photodiode, the light induced electron generated in the attached photodiode 210 is less, therefore first is floating
The parasitic capacitance and the capacitor 270 of sky diffusion point FD1 has enough capacitor space storages to generate from attached photodiode 210
Light induced electron.The brightness of image that the data that so third signal data acquisition obtains can characterize is acquired greater than second signal data
The brightness of image that data can characterize is obtained, improves dynamic range in this way.
In the present embodiment, the brightness of image that the data that third signal data acquisition obtains can characterize is greater than second signal data
Collect the brightness of image that data can characterize.The brightness of image that the data that second signal data collect can characterize is greater than the
The brightness of image that the data that one signal data acquisition obtains can characterize.
Third useful signal data, the second useful signal data and the first useful signal data are merged, obtain one
The complete image of frame.
In the present embodiment, the longer time for exposure is can be used in main exposure sequential step and extended exposure sequential step, because
This is avoided that stroboscopic phenomenon.
Another embodiment of the present invention also provides a kind of image sensor pixel circuit, referring to FIG. 5, image in the present embodiment
The difference of the image sensor pixel circuit of sensor pixel circuits and previous embodiment is: the second transmission transistor 330
Drain electrode the second floating of connection spreads point FD2.It is identical with previous embodiment to close image sensor pixel circuit in this present embodiment
Part, be no longer described in detail.
The source level of second transmission transistor 330 connects attached photodiode 310.
Correspondingly, the present embodiment also provides a kind of working method of image sensor pixel circuit (with reference to Fig. 5), this implementation
Working method is no longer described in detail referring to the working method in previous embodiment in example.
Although present disclosure is as above, present invention is not limited to this.Anyone skilled in the art are not departing from this
It in the spirit and scope of invention, can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the range of restriction.
Claims (13)
1. a kind of image sensor pixel circuit characterized by comprising
Key light electric diode, the key light electric diode have the first positive connecting pin；
Attached photodiode；
First transmission transistor, the source level of the first transmission transistor are connect with the first positive connecting pin, the first transmission transistor
Drain electrode the first floating of connection spreads point；
Second transmission transistor, the source level of the second transmission transistor are connect with the attached photodiode, the second transmission transistor
Drain electrode connect the first floating diffusion point or the second floating spread point；
Extra transistor, first floating that the source electrode of the extra transistor connects spread point, and the drain electrode of the extra transistor connects
Connect the second floating diffusion point；
First reset transistor, the drain electrode of the first reset transistor are connect with the first power supply line, the source level of the first reset transistor
Connect the second floating diffusion point；
Second reset transistor, the source level of the second reset transistor are connect with the first positive connecting pin, the second reset transistor
Drain electrode is connect with second source line；
Capacitor, the capacitor and the diffusion point connection of the second floating；
Column sense line, the column sense line are adapted to read out the electrical potential information of the first floating diffusion point.
2. image sensor pixel circuit according to claim 1, which is characterized in that the key light electric diode it is photosensitive
Area is greater than the photosensitive area of the attached photodiode.
3. image sensor pixel circuit according to claim 2, which is characterized in that the attached photodiode it is photosensitive
Area is the 5%~20% of the photosensitive area of the key light electric diode.
4. image sensor pixel circuit according to claim 1, which is characterized in that further include: follow transistor, institute
Grid and the diffusion point connection of the first floating of follow transistor are stated, the drain electrode of the follow transistor and the first power supply line connect
It connects；The drain electrode of selection transistor, the selection transistor is connect with the source electrode of the follow transistor, the selection transistor
Source electrode connect with the column sense line.
5. image sensor pixel circuit according to claim 1, which is characterized in that the current potential of second source line and first
The current potential of power supply line is identical；Alternatively, the current potential of second source line is different from the current potential of the first power supply line.
6. image sensor pixel circuit according to claim 1, which is characterized in that the capacitor has opposite first
End and second end, first end and the diffusion point connection of the second floating, second end ground connection.
7. image sensor pixel circuit according to claim 1, which is characterized in that the key light electric diode also has
First Opposite direction connection end, the first Opposite direction connection end ground connection；The attached photodiode has the second positive connecting pin and second instead
To connecting pin, the second positive connecting pin connects the source level of the second transmission transistor, the second Opposite direction connection end ground connection.
8. a kind of working method of image sensor pixel circuit characterized by comprising
Image sensor pixel circuit as claimed in any one of claims 1 to 7 is provided；
Carry out main exposure sequential step, in main exposure sequential step, the first reset transistor, the second reset transistor, first
Transmission transistor and the second transmission transistor are in off-state, and the extra transistor is in the conductive state；
After carrying out main exposure sequential step, main readout sequence step is carried out, in main readout sequence step, the second reset transistor
Be in off-state with the second transmission transistor, main readout sequence step include: in the case where extra transistor is in an off state,
First transmission transistor is connected, so that the charge in key light electric diode is spread point to the first floating and carries out the first charging；Into
After row first charges, in the case where extra transistor is in an off state, the column sense line believes the current potential of the first floating diffusion point
Breath carries out the first signal data acquisition；After carrying out the first signal data acquisition, in the case where extra transistor is in the conductive state, conducting
First transmission transistor makes the charge in key light electric diode spread point and the second floating diffusion point progress second to the first floating
Charging；After carrying out the second charging, in the case where extra transistor is in the conductive state, the column sense line is to the first floating diffusion point
Electrical potential information carries out the acquisition of second signal data；
After carrying out main readout sequence step, it is extended exposure time series step, in extended exposure sequential step, described second is multiple
Bit transistor and extra transistor are on state, and the first reset transistor, the first transmission transistor and the second transmission are brilliant
Body pipe is in off-state；
After being extended exposure time series step, it is extended readout sequence step, in extension readout sequence step, second resets
Transistor and extra transistor are on state, and the first transmission transistor is in an off state, the extension readout sequence
Step includes: the second transmission transistor of conducting, and the charge in the attached photodiode is made to spread point and second to the first floating
Floating diffusion point carries out third charging；After carrying out third charging, electrical potential information of the column sense line to the first floating diffusion point
Carry out third signal data acquisition.
9. image sensor pixel circuit according to claim 8, which is characterized in that in the starting of main readout sequence step
The termination moment that moment to second signal data acquire, first reset transistor are in an off state.
10. image sensor pixel circuit according to claim 8, which is characterized in that the main readout sequence step is also
It include: to be in disconnected in the extra transistor, the first reset transistor and the first transmission transistor before the charging of carry out first
Under open state, the column sense line carries out the first reference data acquisition to the electrical potential information of the first floating diffusion point；According to first
The difference for the data that the data and the first signal data acquisition that reference data collects obtain obtains the first useful signal data.
11. image sensor pixel circuit according to claim 8, which is characterized in that the main readout sequence step is also
Include: after carrying out the acquisition of second signal data, carry out master reset operation, master reset operation in, the first reset transistor and
Extra transistor is in the conductive state, and the first transmission transistor is in an off state；After carrying out master reset operation, resetted first
Transistor and the first transmission transistor be in an off state and extra transistor it is in the conductive state under, the column sense line pair
The electrical potential information of first floating diffusion point carries out the second reference data acquisition；The data collected according to the second reference data with
The difference for the data that second signal data collect obtains the second useful signal data.
12. image sensor pixel circuit according to claim 8, which is characterized in that the extension readout sequence step
Further include: after carrying out third signal data acquisition, it is extended reset operation, is resetted in operation in extension, first resets crystal
Manage in the conductive state, the second transmission transistor is in an off state；After being extended reset operation, in the first reset transistor
It is in an off state and the second transmission transistor is in an off state down, electricity of the column sense line to the first floating diffusion point
Position information carries out the acquisition of third reference data；The data collected according to third reference data are obtained with third signal data acquisition
The difference of the data arrived obtains third useful signal data.
13. image sensor pixel circuit according to claim 8, which is characterized in that further include: when carrying out main reading
After sequence step, and before being extended exposure time series step, it is extended emptying step；In extension emptying step, the
One reset transistor and the second reset transistor are in the conductive state, and the first transmission transistor is in an off state, the second transmission
Transistor is in the conductive state, and extra transistor is in the conductive state, and selection transistor is in an off state.
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