CN104394338A - Tri-transistor image sensor pixel structure capable of expanding dynamic range - Google Patents
Tri-transistor image sensor pixel structure capable of expanding dynamic range Download PDFInfo
- Publication number
- CN104394338A CN104394338A CN201410725887.0A CN201410725887A CN104394338A CN 104394338 A CN104394338 A CN 104394338A CN 201410725887 A CN201410725887 A CN 201410725887A CN 104394338 A CN104394338 A CN 104394338A
- Authority
- CN
- China
- Prior art keywords
- transistor
- image sensor
- photodiode
- dynamic range
- capacitance device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
The invention discloses a tri-transistor image sensor pixel structure capable of expanding a dynamic range. The tri-transistor image sensor pixel structure comprises a photodiode, a resetting transistor, a source following transistor and a select transistor which are arranged in a semiconductor base body, and further comprises a transistor capacitor, wherein a gate electrode of the transistor capacitor is connected with the positive electrode of the photodiode; source and drain electrodes of the transistor capacitor are externally connected with controllable potential; under weak light radiation, the transistor capacitor does act, and the photoreceptive sensitivity of the pixels is high; under strong light radiation, the transistor capacitor is added into the photodiode, so that the photoreceptive sensitivity of the pixels is lowered. And therefore, the photoreceptive sensitivity of the strong-light-radiated pixels is compressed, and the dynamic range of the pixels is expanded.
Description
Technical field
The present invention relates to a kind of imageing sensor, particularly a kind of three dynamic range expanded transistor image sensor dot structures.
Background technology
Imageing sensor has been widely used in digital camera, cell phone, medicine equipment, automobile and other application scenarios.Particularly manufacture the fast development of CMOS (CMOS (Complementary Metal Oxide Semiconductor)) image sensor technologies, make the output image quality of people to imageing sensor have higher requirement.
In the prior art, cmos image sensor generally adopts the dot structure of linear photoconductor response function.As shown in Figure 1, cmos image sensor adopts the active pixel of three transistors, in the art also referred to as 3T active pixel, the components and parts of 3T active pixel comprise: photodiode 101, reset transistor 102, source is followed transistor 103 and is selected transistor 104, and row bit line 105; The grid that the positive terminal Vpd of photodiode 101 follows transistor 103 with the source electrode of reset transistor 102 and source is connected, and Vrst is the gate terminal of reset transistor 102, and Vsx is the gate terminal selecting transistor 104, and Vdd is supply voltage.Photodiode 101 receives extraneous incident light, produces photosignal; Open and select transistor 104, to read being followed photodiode 101 potential well built-in potential variable signal that transistor 103 detects by source through row bit line 105 and to preserve.Wherein, the photo-electric charge amount produced in photodiode 101 is directly proportional to incident illumination amount, in photodiode 101 potential well, the change of photo-electric charge is followed transistor 103 by source and is detected and be converted to potential change, and the amount that photo-electric charge is converted to electromotive force is called opto-electronic conversion gain; During the change of photo-electric charge amount, conversion gain remains unchanged, then source follow electric potential signal that transistor 103 detects at photodiode 101 place also with quantity of illumination linear proportional relation.
The photoelectric respone of such imageing sensor is linear, in this area, be called as linear transducer.Linear transducer not easily collects the information in kind of high lighting environment, thus reduces the output image quality of transducer.
Summary of the invention
The object of this invention is to provide a kind of three dynamic range expanded transistor image sensor dot structures of efficient, high photosensitive dynamic range.
The object of the invention is to be achieved through the following technical solutions:
Three dynamic range expanded transistor image sensor dot structures of the present invention, comprise the photodiode, reset transistor, the source that are placed in semiconductor substrate to follow transistor, select transistor, also comprise transistor capacitance device, the grid of described transistor capacitance device is connected with the positive pole of described photodiode, the source-drain electrode of described transistor capacitance device interconnects, and external controlled electromotive force.
As seen from the above technical solution provided by the invention, the three dynamic range expanded transistor image sensor dot structures that the embodiment of the present invention provides, owing to also comprising transistor capacitance device, the grid of transistor capacitance device is connected with the positive pole of photodiode, the external controlled electromotive force of its source-drain electrode; During low light irradiation, transistor capacitance is inoperative, and the luminous sensitivity of pixel is high; During strong illumination, transistor capacitance adds in photodiode, and the luminous sensitivity of pixel reduces.Therefore, the present invention have compressed the luminous sensitivity of strong illumination pixel, extends the dynamic range of pixel.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of three transistors (3T) active pixel of the imageing sensor of prior art;
Fig. 2 is the circuit diagram of the three dynamic range expanded transistor image sensor dot structures of the embodiment of the present invention;
Fig. 3 is the potential well schematic diagram of the photodiode of the three dynamic range expanded transistor image sensor dot structures of the embodiment of the present invention;
Fig. 4 is the three dynamic range expanded transistor image sensor dot structures of embodiment of the present invention photodiode potential well schematic diagrames when being subject to low light irradiation.
Fig. 5 is the three dynamic range expanded transistor image sensor dot structures of embodiment of the present invention photodiode potential well schematic diagrames when being subject to strong illumination.
Fig. 6 is the photoelectric respone curve synoptic diagram of the three dynamic range expanded transistor image sensor dot structures of the embodiment of the present invention.
Embodiment
To be described in further detail the embodiment of the present invention below.
Three dynamic range expanded transistor image sensor dot structures of the present invention, its preferably embodiment be:
Comprise the photodiode, reset transistor, the source that are placed in semiconductor substrate to follow transistor, select transistor, also comprise transistor capacitance device, the grid of described transistor capacitance device is connected with the positive pole of described photodiode, the source-drain electrode of described transistor capacitance device interconnects, and external controlled electromotive force.
Described photodiode is N-type photodiode, and described transistor capacitance device is P-type crystal pipe.
The threshold voltage of described transistor capacitance device is-0.7V ~ 0V.
The capacitance of described transistor capacitance device is more than or equal to 1fF.
The external electromotive force of source-drain electrode of described transistor capacitance device is more than or equal to 0.7V.
In three transistor image sensors, in order to improve the image quality collected, the present invention starts with from optimization dot structure, on three transistor image sensor dot structure bases in the prior art, add a N-type MOS transistor capacitor element, and the grid of transistor capacitance device is connected with the positive pole of N-type photodiode, the external controlled electromotive force of its source-drain electrode.Image sensor pixel of the present invention, during low light irradiation, after pixel integration, the photo-electric charge amount that photodiode collection arrives is few, the potential well electromotive force of photodiode is high, namely the grid potential of transistor capacitance device is high, electrical potential difference between its grid and source-drain electrode is greater than its threshold voltage, transistor capacitance device is made to be operated in by district, therefore the electric capacity of transistor capacitance device is invalid, photo-electric charge conversion gain in photodiode potential well remains unchanged, identical with the opto-electronic conversion gain of three transistor image sensor pixels of the prior art, so the luminous sensitivity of the pixel of low light irradiation keeps higher level, during strong illumination, after pixel integration, the photo-electric charge amount that photodiode collection arrives is many, the potential well electromotive force of photodiode is low, namely the grid potential of transistor capacitance device is low, electrical potential difference between its grid and source-drain electrode is less than its threshold voltage, transistor capacitance device is made to be operated in linear zone, therefore the electric capacity of transistor capacitance device reaches its Stability Design value, this electric capacity joins in photodiode, electric capacity in photodiode potential well is now transistor capacitance device electric capacity and photodiode original capacitance sum, its photo-electric charge conversion gain and total capacitance are inversely, because this reducing the opto-electronic conversion gain of photo-electric charge, and then reduce the luminous sensitivity of pixel, postpone the photosensitive saturation time of pixel, extend the dynamic range of pixel.
Specific embodiment:
The circuit diagram of three transistor image sensor pixels of the embodiment of the present invention, as shown in Figure 2.In Fig. 2,201 is photodiode, and 202 is reset transistor, and 203 for following transistor in source, and 204 for selecting transistor, and 205 is row bit line, and 206 is transistor capacitance device; Wherein, VPD is the positive terminal of photodiode 201, and be connected with the gate terminal of transistor capacitance device 206, the gate terminal of following transistor 203 with source is connected, be connected with the source terminal of reset transistor 202, VRX is the gate terminal of reset transistor 202, and VSX is the gate terminal selecting transistor 204, and Vdd is supply voltage; The source-drain electrode of described transistor capacitance device 206 interconnects, and external controlled electromotive force Vct.Described photodiode 201 is N-type photodiode, described transistor capacitance device 206 is N-type MOS transistor, the threshold voltage of described transistor capacitance device 206 is-0.7V ~ 0V, the capacitance of described transistor capacitance device 206 is more than or equal to 1fF, the external electromotive force of source-drain electrode of described transistor capacitance device 206 is more than or equal to 0.7V, and the semiconductor substrate that described photodiode 201 uses is P type semiconductor matrix.
The potential well schematic diagram of the photodiode in three transistor image sensor pixels of the present invention, as shown in Figure 3,301 potential well areas are the original potential well of photodiode 201,302 potential well areas are the potential well of transistor capacitance device 206, and the electric capacity of 301 potential well areas is Cpd, and the electric capacity of 302 potential well areas is Cap, wherein Ccap is more than or equal to 1fF, Vreset is the maximum potential value of 301 potential well areas, and Vth is the threshold voltage of transistor capacitance device 206, and wherein the scope of Vth is-0.7V ~ 0V.
Three transistor image sensor pixels of the present invention, when being subject to low light irradiation, paxel integration time terminates, the potential well schematic diagram of its photodiode, as shown in Figure 4.A small amount of photo-electric charge collected by photodiode 201, is only stored in 301 potential well areas, and the opto-electronic conversion gain of photo-electric charge is inversely proportional to Cpd, identical with the opto-electronic conversion gain of three transistor image sensor pixels of the prior art; Pixel luminous sensitivity direct ratio during described low light irradiation and opto-electronic conversion gain, therefore, the luminous sensitivity of pixel is identical with the luminous sensitivity of three transistor image sensor pixels of the prior art, remains on higher level.
Three transistor image sensor pixels of the present invention, when being subject to strong illumination, paxel integration time terminates, the potential well schematic diagram of its photodiode, as shown in Figure 5.A large amount of photo-electric charge collected by photodiode 201, not only be stored in 301 potential well areas, and be also stored in 302 potential well areas, the opto-electronic conversion gain of photo-electric charge is inversely proportional to Cpd and Ccap electric capacity sum, lower than the opto-electronic conversion gain of three transistor image sensor pixels of the prior art; Pixel luminous sensitivity direct ratio during described strong illumination and opto-electronic conversion gain, therefore, compared with the luminous sensitivity of three transistor image sensor pixels of the prior art, the luminous sensitivity of three transistor image sensor pixels of the present invention is low.So three transistor image sensor pixels of the present invention, have compressed the luminous sensitivity of strong illumination pixel, have postponed the saturation time of pixel.
The photoelectric respone curve synoptic diagram of three transistor image sensor pixels of the embodiment of the present invention, as shown in Figure 6.In Fig. 6, trunnion axis is the exposure of pixel, and vertical axes is pixel light signal of telecommunication amount, and wherein photosignal amount unit is volt.Described photoelectricity response curve, is divided into two sections: high-conversion-gain district and low conversion gain district, and high-conversion-gain district part corresponds to the pixel of low light irradiation, and wherein A point position mark is situation shown in Fig. 4; Low conversion gain district part corresponds to the pixel of strong illumination, and wherein B point position mark is situation shown in Fig. 5.The photoelectricity electric potential signal at high-conversion-gain district and tie point place of low conversion gain district is Vreset-Vct-Vth, corresponding with the potential point Vct+Vth shown in Fig. 5, and this pixel exposure amount is Ect; Vsat shown in Fig. 6 is the signal saturation capacity of pixel, and Esat1 is exposure when three transistor image sensor pixels are saturated in prior art, Esat2 be three transistor image sensor pixels of the present invention saturated time exposure.The dynamic range of three transistor image sensor pixels of the present invention extend to Esat2 from Esat1.As can be seen here, the present invention three transistor image sensor pixel, have compressed the luminous sensitivity of strong illumination pixel, extends the dynamic range of pixel.
The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.
Claims (5)
1. dynamic range expanded three transistor image sensor dot structures, comprise the photodiode, reset transistor, the source that are placed in semiconductor substrate to follow transistor, select transistor, it is characterized in that, also comprise transistor capacitance device, the grid of described transistor capacitance device is connected with the positive pole of described photodiode, the source-drain electrode of described transistor capacitance device interconnects, and external controlled electromotive force.
2. three dynamic range expanded transistor image sensor dot structures according to claim 1, it is characterized in that, described photodiode is N-type photodiode, and described transistor capacitance device is P-type crystal pipe.
3. three dynamic range expanded transistor image sensor dot structures according to claim 2, is characterized in that, the threshold voltage of described transistor capacitance device is-0.7V ~ 0V.
4. three dynamic range expanded transistor image sensor dot structures according to claim 3, it is characterized in that, the capacitance of described transistor capacitance device is more than or equal to 1fF.
5. three dynamic range expanded transistor image sensor dot structures according to claim 4, is characterized in that, the external electromotive force of source-drain electrode of described transistor capacitance device is more than or equal to 0.7V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410725887.0A CN104394338A (en) | 2014-12-03 | 2014-12-03 | Tri-transistor image sensor pixel structure capable of expanding dynamic range |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410725887.0A CN104394338A (en) | 2014-12-03 | 2014-12-03 | Tri-transistor image sensor pixel structure capable of expanding dynamic range |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104394338A true CN104394338A (en) | 2015-03-04 |
Family
ID=52612167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410725887.0A Pending CN104394338A (en) | 2014-12-03 | 2014-12-03 | Tri-transistor image sensor pixel structure capable of expanding dynamic range |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104394338A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105762160A (en) * | 2016-02-19 | 2016-07-13 | 上海集成电路研发中心有限公司 | Backside illumination global pixel unit structure and preparation method thereof |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6246436B1 (en) * | 1997-11-03 | 2001-06-12 | Agilent Technologies, Inc | Adjustable gain active pixel sensor |
| US20040079977A1 (en) * | 2002-10-29 | 2004-04-29 | Ying Bond Y. | CMOS image sensor with variable conversion gain |
| US20050224843A1 (en) * | 2004-04-07 | 2005-10-13 | Christian Boemler | High dynamic range pixel amplifier |
| CN102170533A (en) * | 2010-02-26 | 2011-08-31 | 索尼公司 | Solid-state image pickup apparatus, driving method for solid-state image pickup apparatus and electronic device |
| CN103139499A (en) * | 2013-03-21 | 2013-06-05 | 北京思比科微电子技术股份有限公司 | Imaging sensor active pixel and imaging sensor with variable conversion gain |
| CN103701411A (en) * | 2013-12-13 | 2014-04-02 | 电子科技大学 | CMOS (complementary metal oxide semiconductor) relaxation oscillator with temperature and process self-compensating characteristics |
| CN203645628U (en) * | 2013-12-13 | 2014-06-11 | 无锡成电科大科技发展有限公司 | Self-compensation type CMOS relaxation oscillation device |
| CN204217043U (en) * | 2014-12-03 | 2015-03-18 | 北京思比科微电子技术股份有限公司 | Three dynamic range expanded transistor image sensor dot structures |
-
2014
- 2014-12-03 CN CN201410725887.0A patent/CN104394338A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6246436B1 (en) * | 1997-11-03 | 2001-06-12 | Agilent Technologies, Inc | Adjustable gain active pixel sensor |
| US20040079977A1 (en) * | 2002-10-29 | 2004-04-29 | Ying Bond Y. | CMOS image sensor with variable conversion gain |
| US20050224843A1 (en) * | 2004-04-07 | 2005-10-13 | Christian Boemler | High dynamic range pixel amplifier |
| CN102170533A (en) * | 2010-02-26 | 2011-08-31 | 索尼公司 | Solid-state image pickup apparatus, driving method for solid-state image pickup apparatus and electronic device |
| CN103139499A (en) * | 2013-03-21 | 2013-06-05 | 北京思比科微电子技术股份有限公司 | Imaging sensor active pixel and imaging sensor with variable conversion gain |
| CN103701411A (en) * | 2013-12-13 | 2014-04-02 | 电子科技大学 | CMOS (complementary metal oxide semiconductor) relaxation oscillator with temperature and process self-compensating characteristics |
| CN203645628U (en) * | 2013-12-13 | 2014-06-11 | 无锡成电科大科技发展有限公司 | Self-compensation type CMOS relaxation oscillation device |
| CN204217043U (en) * | 2014-12-03 | 2015-03-18 | 北京思比科微电子技术股份有限公司 | Three dynamic range expanded transistor image sensor dot structures |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105762160A (en) * | 2016-02-19 | 2016-07-13 | 上海集成电路研发中心有限公司 | Backside illumination global pixel unit structure and preparation method thereof |
| CN105762160B (en) * | 2016-02-19 | 2020-06-09 | 上海集成电路研发中心有限公司 | Back-illuminated global pixel unit structure and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4825982B2 (en) | Solid-state imaging device and signal readout method thereof | |
| CN103067676B (en) | Highly-dynamic image sensor and active pixel thereof | |
| CN104469195A (en) | High-dynamic-range image sensor pixel structure and operation method thereof | |
| CN103139499B (en) | There is imageing sensor active pixel and the imageing sensor of variable conversion gain | |
| CN204217043U (en) | Three dynamic range expanded transistor image sensor dot structures | |
| CN105227870B (en) | Larger Dynamic range line-log responds cmos image sensor | |
| WO2018086342A1 (en) | Pixel sensing circuit, driving method thereof, image sensor, and electronic device | |
| CN104485342A (en) | Pixel structure of image sensor and operating method for pixel structure | |
| US10880510B2 (en) | Circuit of detecting light, image sensor and electronic device using the same and method of detecting light based on the same | |
| US11221422B2 (en) | Pixel structure of flat panel detection device, flat panel detection device and camera system | |
| CN104135632B (en) | Non-linear cmos image sensor pixel and its method of work | |
| CN110460786B (en) | Pixel sensing circuit, first bias voltage determining method and electronic equipment | |
| CN103022069B (en) | Imageing sensor | |
| CN104135633A (en) | Image sensor pixel with changeable conversion gain and working method thereof | |
| CN104010142A (en) | Active pixel, image sensor and control timing sequence thereof | |
| CN204031312U (en) | The image sensor pixel of variable conversion gain | |
| KR100898908B1 (en) | Active pixel sensor | |
| JP6308404B2 (en) | Image sensor having solar cell function and electronic device using the same | |
| CN103139497B (en) | The active pixel and cmos image sensor of cmos image sensor | |
| CN104135631A (en) | CMOS image sensor pixel | |
| CN103491323A (en) | Pixel unit of CMOS image sensor | |
| CN104394338A (en) | Tri-transistor image sensor pixel structure capable of expanding dynamic range | |
| CN206042183U (en) | Compound CMOS image sensor | |
| CN204069153U (en) | Active pixel structure and imageing sensor | |
| CN204258952U (en) | High dynamic range image sensor dot structure |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20150304 |
|
| RJ01 | Rejection of invention patent application after publication |