• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A CMOS image sensor for providing a wider dynamic range even at a low power supply voltage level includes a plurality of unit pixels and a control unit. Each unit pixel includes: a light sensing element for sensing an incident light to generate photoelectric charges to a sensing node; a first switching unit, coupled between a power terminal and the sensing node, for transferring a reset voltage level from a voltage source to the light sensing element; an amplification unit for amplifying a voltage level of the sensing node to output an amplified signal, wherein one terminal of the amplification unit is coupled to a ground terminal; a second switching unit, coupled between an output node and the other terminal of the amplification unit, for outputting the amplified signal as an image data via the output node. The control unit, which is coupled between the power terminal and the output node, controls an output resistance of the output node.
    公开号:US20010005224A1
    申请号:US09/749,572
    申请日:2000-12-28
    公开日:2001-06-28
    发明作者:Do-Young Lee
    申请人:Hynix Semiconductor Inc；
    IPC主号:H04N3-155
    专利说明:
    [0001] The present invention relates to a semiconductor device; and, more particularly, to a CMOS image sensor for providing a wider dynamic range at a low power supply voltage level, thereby obtaining a high image quality. [0001] DESCRIPTION OF THE PRIOR ART
    [0002] As is well known, an image sensor is an apparatus for sensing a light beam reflected from an object to generate an image data. Especially, an image sensor fabricated by using a complementary metal oxide semiconductor (CMOS) technology is called a CMOS image sensor. [0002]
    [0003] Generally, the CMOS image sensor includes a plurality of unit pixels. Each of the unit pixels also includes a light sensing element and a plurality of transistors. The light sensing element such as a photodiode senses incident light beam to generate photoelectric charges corresponding to an amount of the incident light beam. The transistors perform switching operations to control a transfer of the photoelectric charges. [0003]
    [0004] At this time, in order for obtaining a high image quality, a large power supply voltage level is required. In general, the CMOS image sensor uses a power supply voltage of about 5 V. However, as a degree of integration in the CMOS image sensor becomes increasingly higher, the power supply voltage level applied to the CMOS image sensor is also being lower. [0004]
    [0005] FIG. 1 is a circuit diagram showing a conventional CMOS image sensor. [0005]
    [0006] Referring to FIG. 1, the conventional CMOS image sensor includes a unit pixel [0006] 10, and the unit pixel 10 includes a photodiode 12 and four transistors. Four transistors also include a transfer transistor MT, a reset transistor MR, a drive transistor MD and a select transistor MS. Further, the CMOS image sensor includes a load transistor ML coupled to the unit pixel 10.
    [0007] The photodiode [0007] 12 senses an incident light to generate photoelectric charges. The transfer transistor MT, coupled between the photodiode 12 and a sensing node NS, transfers the photoelectric charges to the sensing node NS. The reset transistor MR, coupled between a power terminal VDD and the sensing node NS, transfers a reset voltage level from a voltage source to the photodiode 12 and the drive transistor MD.
    [0008] The drive transistor MD, whose drain is coupled to the power terminal VDD, amplifies a voltage level of the sensing node NS to output an amplified signal. The select transistor MS, coupled between the drive transistor MD and an output node NO, performs a switching operation to output the amplified signal as an image data via the output node NO. [0008]
    [0009] The load transistor ML, coupled between the output node NO and a ground terminal GND, controls a current that flows via the output node NO of the unit pixel [0009] 10.
    [0010] At this time, the conventional unit pixel [0010] 10 has a dynamic range of about 1.5 V under the power supply voltage level of 5 V. If the power supply voltage level is decreased, the photoelectric charges accumulated in the photodiode 12 is also reduced and a dynamic range of the CMOS image sensor becomes narrower, thereby degrading an image quality. Therefore, there is a demand on a unit pixel capable of providing a wider dynamic range even at a low power supply voltage level. SUMMARY OF THE INVENTION
    [0011] It is, therefore, an object of the present invention to provide a CMOS image sensor for providing a wider dynamic range at a low power supply voltage level to thereby obtain a high image quality. [0011]
    [0012] In accordance with an embodiment of the present invention, there is provided a CMOS image sensor, comprising: a light sensing means for sensing an incident light to generate photoelectric charges to a sensing node; a first switching means, coupled between a power terminal and the sensing node, for transferring a reset voltage level from a voltage source to the light sensing means; an amplification means for amplifying a voltage level of the sensing node to output an amplified signal, wherein one terminal of the amplification means is coupled to a ground terminal; a second switching means, coupled between an output node and the other terminal of the amplification means, for outputting the amplified signal as an image data via the output node; and a control means, coupled between the power terminal and the output node, for controlling an output resistance of the output node. [0012] BRIEF DESCRIPTION OF THE DRAWINGS
    [0013] Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, in which: [0013]
    [0014] FIG. 1 is a circuit diagram showing a conventional CMOS image sensor; [0014]
    [0015] FIG. 2 is a circuit diagram illustrating a CMOS image sensor in accordance with an embodiment of the present invention; and [0015]
    [0016] FIG. 3 is a circuit diagram illustrating a CMOS image sensor in accordance with another embodiment of the present invention. [0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
    [0017] FIG. 2 is a circuit diagram illustrating a CMOS image sensor in accordance with an embodiment of the present invention. [0017]
    [0018] Referring to FIG. 2, the CMOS image sensor in accordance with an embodiment of the present invention includes a unit pixel [0018] 200 and a control unit 220. The unit pixel 200 also includes a photodiode 210 as a light sensing element and four NMOS transistors as switching elements. Four NMOS transistors also include a transfer transistor MT2, a reset transistor MR2, a drive transistor MD2 and a select transistor MS2.
    [0019] The photodiode [0019] 210 senses an incident light to generate photoelectric charges. The transfer transistor MT2, coupled between the photodiode 210 and a sensing node NS2, transfers the photoelectric charges to the sensing node NS2. The reset transistor MR2, coupled between a power terminal VDD and the sensing node NS2, transfers a reset voltage level from a voltage source to the photodiode 210 and the drive transistor MD2.
    [0020] The drive transistor MD[0020] 2, whose source is coupled to a ground terminal GND, amplifies a voltage level of the sensing node NS2 to output an amplified signal. The select transistor MS2, coupled between an output node NO2 and a drain of the drive transistor MD2, performs a switching operation to output the amplified signal as an image data via the output node NO2.
    [0021] The control unit [0021] 220 includes a PMOS transistor P20 coupled between the power terminal VDD and the output node NO2. The PMOS transistor P20 is responsive to a bias voltage Vb. Preferably, the control unit 220 further includes a diode-connected PMOS transistor P21, coupled in parallel to the PMOS transistor P20. The diode-connected PMOS transistor P21 controls an output resistance of the output node NO2 to thereby minimize a current that flows via the output node NO2.
    [0022] FIG. 3 is a circuit diagram illustrating a CMOS image sensor in accordance with another embodiment of the present invention. [0022]
    [0023] Referring to FIG. 3, the unit pixel in accordance with another embodiment of the present invention includes a unit pixel [0023] 300 and a control unit 320. Compared with the unit pixel 200 shown in FIG. 2, only difference is that the unit pixel 300 includes three NMOS transistors, i.e., a reset transistor MR3, a drive transistor MD3 and a select transistor MS.
    [0024] At this time, the drive transistor MD contained in the conventional unit pixel [0024] 10 performs a signal transfer function rather than a signal amplification function. Meanwhile, the drive transistors MD2 and MD3 contained in the CMOS image sensor in accordance with the present invention performs a signal amplification function as well as a signal transfer function, thereby obtaining a wider dynamic range. Additionally, since the control units 220 and 230 respectively control the output resistances of the output nodes NO2 and NO3, the CMOS image sensor can stably operate.
    [0025] Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. [0025]
    权利要求:
    Claims (13)
    [1" id="US-20010005224-A1-CLM-00001] 1. A CMOS image sensor, comprising:
    a light sensing means for sensing an incident light to generate photoelectric charges to a sensing node;
    a first switching means, coupled between a power terminal and the sensing node, for transferring a reset voltage level from a voltage source to the light sensing means;
    an amplification means for amplifying a voltage level of the sensing node to output an amplified signal, wherein one terminal of the amplification means is coupled to a ground terminal;
    a second switching means, coupled between an output node and the other terminal of the amplification means, for outputting the amplified signal as an image data via the output node; and
    a control means, coupled between the power terminal and the output node, for controlling an output resistance of the output node.
    [2" id="US-20010005224-A1-CLM-00002] 2. The CMOS image sensor as recited in
    claim 1 , wherein the light sensing means is a photodiode.
    [3" id="US-20010005224-A1-CLM-00003] 3. The CMOS image sensor as recited in
    claim 2 , wherein the first switching means and the second switching means are NMOS transistors.
    [4" id="US-20010005224-A1-CLM-00004] 4. The CMOS image sensor as recited in
    claim 3 , wherein the amplification means is an NMOS transistor.
    [5" id="US-20010005224-A1-CLM-00005] 5. The CMOS image sensor as recited in
    claim 1 , wherein the control means includes a PMOS transistor coupled between the power terminal and the output node.
    [6" id="US-20010005224-A1-CLM-00006] 6. The CMOS image sensor as recited in
    claim 5 , wherein the control means further includes a diode-connected PMOS transistor coupled in parallel to the PMOS transistor.
    [7" id="US-20010005224-A1-CLM-00007] 7. The CMOS image sensor as recited in
    claim 1 , further comprising a third switching means, coupled between the light sensing means and the sensing node, for transferring the photoelectric charges to the sensing node.
    [8" id="US-20010005224-A1-CLM-00008] 8. The CMOS image sensor as recited in
    claim 7 , wherein the third switching means is an NMOS transistor.
    [9" id="US-20010005224-A1-CLM-00009] 9. The CMOS image sensor as recited in
    claim 8 , wherein the light sensing means is a photodiode.
    [10" id="US-20010005224-A1-CLM-00010] 10. The CMOS image sensor as recited in
    claim 9 , wherein the first and the second means are NMOS transistors.
    [11" id="US-20010005224-A1-CLM-00011] 11. The CMOS image sensor as recited in
    claim 10 , wherein the amplification means is an NMOS transistor.
    [12" id="US-20010005224-A1-CLM-00012] 12. The CMOS image sensor as recited in
    claim 11 , wherein the control means includes a PMOS transistor coupled between the power terminal and the output node.
    [13" id="US-20010005224-A1-CLM-00013] 13. The CMOS image sensor as recited in
    claim 12 , wherein the control means further includes a diode-connected PMOS transistor coupled in parallel to the PMOS transistor.
    类似技术:
    公开号 | 公开日 | 专利标题
    US7183531B2|2007-02-27|Amplification with feedback capacitance for photodetector signals
    US8368790B2|2013-02-05|Image sensing apparatus and imaging system
    US7157683B2|2007-01-02|Method, apparatus and system providing configurable current source device for image sensors
    US6618083B1|2003-09-09|Mismatch-independent reset sensing for CMOS area array sensors
    US7916199B2|2011-03-29|Photo detection device
    JP4362156B2|2009-11-11|Sequential correlation double sampling method for CMOS area array sensor
    US7391004B2|2008-06-24|Photo detecting apparatus
    US20030164443A1|2003-09-04|Image sensor
    US6952227B2|2005-10-04|CMOS image sensor for providing wider dynamic range
    US6501064B2|2002-12-31|Image sensor with active sensor elements
    JP4654046B2|2011-03-16|Clamp circuit for CMOS image sensor
    EP0851670A2|1998-07-01|Photoelectric conversion apparatus
    CN112584069A|2021-03-30|Image sensor and method of operating the same
    US6849845B2|2005-02-01|Low power integrating circuit for use with a photodetector and optical sensor including such an integrating circuit
    KR100436074B1|2004-06-12|Amplification type solid states imaging device output circuit capable of stably operating at a low voltage
    US7869100B2|2011-01-11|Image sensor, module and electronic device
    JPH11274463A|1999-10-08|Solid image pickup element
    JP2008135929A|2008-06-12|Optical sensor circuit and optical sensor array
    KR100694463B1|2007-03-12|Calibration circuit and image sensor having the same
    KR20150130186A|2015-11-23|Image sensor and stacked structure thereof
    JP2002185702A|2002-06-28|Image sensor and image sensor unit
    同族专利:
    公开号 | 公开日
    JP2001238133A|2001-08-31|
    FR2803158A1|2001-06-29|
    US6952227B2|2005-10-04|
    KR20010061385A|2001-07-07|
    FR2803158B1|2002-06-14|
    KR100429571B1|2004-05-03|
    TW466663B|2001-12-01|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5572074A|1995-06-06|1996-11-05|Rockwell International Corporation|Compact photosensor circuit having automatic intensity range control|
    US5742047A|1996-10-01|1998-04-21|Xerox Corporation|Highly uniform five volt CMOS image photodiode sensor array with improved contrast ratio and dynamic range|
    US5898168A|1997-06-12|1999-04-27|International Business Machines Corporation|Image sensor pixel circuit|
    US6556244B1|1997-09-25|2003-04-29|Hyundai Electronics Industries Co., Ltd.|Active pixel sensor with electronic shutter|
    US6670990B1|1997-09-29|2003-12-30|Canon Kabushiki Kaisha|Image sensing device using MOS-type image sensing element whose threshold voltage of charge transfer switch and reset switch is different from that of signal output transistor|
    US6297492B1|1998-01-06|2001-10-02|Intel Corporation|Fast BICMOS active-pixel sensor cell with fast NPN emitter-follower readout|
    US6111245A|1998-04-22|2000-08-29|National Science Council Of Republic Of China|Low voltage reverse bias arrangement for an active pixel sensor|
    US6130423A|1998-07-10|2000-10-10|Pixel Cam, Inc.|Method and apparatus for a CMOS image sensor with a distributed amplifier|
    US6242728B1|1998-08-20|2001-06-05|Foveon, Inc.|CMOS active pixel sensor using native transistors|US20030201518A1|2002-04-30|2003-10-30|Mann Richard A.|Suppressing radiation charges from reaching dark signal sensor|
    US20050121519A1|2003-12-05|2005-06-09|Canon Kabushiki Kaisha|Solid state image pickup device, method of driving solid state image pickup device, and camera using the solid state image pickup device|
    US20080157151A1|2006-12-27|2008-07-03|Dongbu Hitek Co., Ltd.|CMOS image sensor|
    CN102379120A|2009-03-13|2012-03-14|新成像技术公司|Low consumption matrix sensor|
    WO2016006153A1|2014-07-08|2016-01-14|Sony Corporation|Image pickup device, electronic apparatus, radiation detection apparatus and method for an image pickup device|JPH01196165A|1988-02-01|1989-08-07|Fuji Photo Film Co Ltd|Solid-state image sensing device|
    JPH11112016A|1997-10-06|1999-04-23|Canon Inc|Driving method for solid-state image pickup device and photoelectric conversion device|
    TW396707B|1998-02-20|2000-07-01|Canon Kk|Semiconductor device|US7057656B2|2000-02-11|2006-06-06|Hyundai Electronics Industries Co., Ltd.|Pixel for CMOS image sensor having a select shape for low pixel crosstalk|
    JP3992504B2|2002-02-04|2007-10-17|富士通株式会社|CMOS image sensor|
    JP3824965B2|2002-05-17|2006-09-20|東光株式会社|Solid-state image sensor|
    KR100640964B1|2004-12-30|2006-11-02|동부일렉트로닉스 주식회사|Unit pixel circuit in CMOS image sensor|
    KR100885921B1|2007-06-07|2009-02-26|삼성전자주식회사|Image sensor detecting light on backside|
    US8736726B2|2007-06-27|2014-05-27|Micron Technology, Inc.|Pixel to pixel charge copier circuit apparatus, systems, and methods|
    KR100871797B1|2007-08-27|2008-12-02|주식회사 동부하이텍|Image sensor|
    TWI569644B|2015-04-20|2017-02-01|財團法人工業技術研究院|Image-sensing device,system and method thereof and charge-sensing device|
    法律状态:
    2004-10-12| AS| Assignment|Owner name: HYNIX SEMICONDUCTOR INC., KOREA, REPUBLIC OF Free format text: CHANGE OF NAME;ASSIGNOR:HYUNDAI ELECTRONICS INDUSTRIES CO., LTD.;REEL/FRAME:015238/0812 Effective date: 20010329 |
    2005-01-10| AS| Assignment|Owner name: MAGNACHIP SEMICONDUCTOR, LTD., KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HYNIX SEMICONDUCTOR, INC.;REEL/FRAME:016216/0649 Effective date: 20041004 |
    2005-04-27| AS| Assignment|Owner name: HYUNDAI ELECTRONICS INDUSTRIES CO., LTD., KOREA, R Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEE, DO-YOUNG;REEL/FRAME:016173/0898 Effective date: 20001218 Owner name: HYUNDAI ELECTRONICS INDUSTRIES CO., LTD., KOREA, R Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEE, DO-YOUNG;REEL/FRAME:016528/0199 Effective date: 20001218 |
    2005-09-14| STCF| Information on status: patent grant|Free format text: PATENTED CASE |
    2009-02-18| AS| Assignment|Owner name: U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL TRUS Free format text: AFTER-ACQUIRED INTELLECTUAL PROPERTY KUN-PLEDGE AGREEMENT;ASSIGNOR:MAGNACHIP SEMICONDUCTOR, LTD.;REEL/FRAME:022277/0133 Effective date: 20090217 |
    2009-03-04| FPAY| Fee payment|Year of fee payment: 4 |
    2009-05-30| AS| Assignment|Owner name: CROSSTEK CAPITAL, LLC, DELAWARE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MAGNACHIP SEMICONDUCTOR, LTD.;REEL/FRAME:022764/0270 Effective date: 20090514 Owner name: CROSSTEK CAPITAL, LLC,DELAWARE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MAGNACHIP SEMICONDUCTOR, LTD.;REEL/FRAME:022764/0270 Effective date: 20090514 |
    2009-08-10| AS| Assignment|Owner name: MAGNACHIP SEMICONDUCTOR, LTD., KOREA, REPUBLIC OF Free format text: PARTIAL RELEASE OF SECURITY INTEREST;ASSIGNOR:U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL TRUSTEE;REEL/FRAME:023075/0054 Effective date: 20090527 Owner name: MAGNACHIP SEMICONDUCTOR, LTD.,KOREA, REPUBLIC OF Free format text: PARTIAL RELEASE OF SECURITY INTEREST;ASSIGNOR:U.S. BANK NATIONAL ASSOCIATION, AS COLLATERAL TRUSTEE;REEL/FRAME:023075/0054 Effective date: 20090527 |
    2011-07-22| AS| Assignment|Owner name: INTELLECTUAL VENTURES II LLC, DELAWARE Free format text: MERGER;ASSIGNOR:CROSSTEK CAPITAL, LLC;REEL/FRAME:026637/0632 Effective date: 20110718 |
    2013-03-18| FPAY| Fee payment|Year of fee payment: 8 |
    2017-03-27| FPAY| Fee payment|Year of fee payment: 12 |
    优先权:
    申请号 | 申请日 | 专利标题
    KR10-1999-0063879A|KR100429571B1|1999-12-28|1999-12-28|Unit pixel circuit and read out circuit for improving image quality and low power voltage in image sensor|
    KR1999-63879||1999-12-28||
    [返回顶部]