共查询到19条相似文献,搜索用时 265 毫秒
1.
2.
4.
提出了一种梯度自适应的宽动态CMOS图像传感器像素结构。该像素结构采用多路分流设计,改变了3T-APS图像传感器的单线性响应率;根据不同的光照强度自适应调整响应率,在低照度时具有较大的响应率,在高照度时具有较小的响应率,从而增大了像素的动态范围。该像素结构简单,无需额外复杂的控制电路即可实现对光照强度的自适应梯度响应。基于0.18 μm 1P4M SMIC工艺,采用SILVACO TCAD仿真软件进行电路设计和仿真。结果表明,该CMOS图像传感器像素结构电路的动态范围可达到112.36 dB。 相似文献
5.
阐述了一种简化4T像素结构的设计。较普通4T像素结构而言,该简化结构像素内部去掉了行选通管,从而提高了像素的填充因子,简化了内部电路设计,减小了版图的面积,消除了行选通管引入的随机噪声。该像素结构采用0.11μm CIS工艺,成功应用于一款像素阵列为640×480的CMOS图像传感器芯片,经过流片测试,芯片整体性能达到了预期的设计目标。 相似文献
6.
7.
8.
像素复位电路是CMOS图像传感器的重要组成部分,其特性直接影响着图像的质量.本文对CMOS APS图像传感器的动态范围、抗饱和能力、图像滞后以及非线性等性能进行了分析,并讨论了通过复位电路改善CMOS图像传感器性能的方法.在本文中,设计了两种带有抗饱和电路的硬复位电路,一种是采用传统的交叉耦合结构实现电压转换,另一种是基于改进的锁存器结构并增加阈值补偿管来实现,两种方案各具特点,分别适用不同的应用要求.仿真结果表明,两种电路方案均能够使动态范围提高2~3dB,增强像素抗饱和能力,同时消除了图像滞后与弱光下的非线性. 相似文献
9.
10.
CMOS图像传感器的设计考虑 总被引:1,自引:0,他引:1
由于CMOS图像传感器的应用,新一代图像系统的开发研制已经得到了极大的加快。这些芯片采用与调制解调器、传真机、便携式移动电话以及微处理器相同的设备制造,并且随着经济规模的形成,其生产成本也得到了降低。现在,CMOS图像传感器的画面质量已能够与CCD图像传感器相媲美了,这主要归功于图像传感器芯片设计的改进,以及亚微米级设计水平增加了像素内部新的功能。实际上CCMOS图像传感器更确切地说应当是一个图像系统。一个典型的CMOS图像传感器通常包含有:一个图像传感器核心(是将离散信号电平多路复用传送到一个单一的输出,… 相似文献
11.
An approach to obtain the pinch-off voltage of 4-T pixel in CMOS image sensor is presented.This new approach is based on the assumption that the photon shot noise in image signal is impacted by a potential well structure change of pixel.Experimental results show the measured pinch-off voltage is consistent with theoretical prediction.This technique provides an experimental method to assist the optimization of pixel design in both the photodiode structure and fabrication process for the 4-T CMOS image sen... 相似文献
12.
The electron potential of a photodiode in a CMOS image sensor should be designed precisely since the charge capacity of the photodiode decreases as the pixel area shrinks. The pinch-off voltage of a photodiode, which also affects the electron capacity, is dependant on the doping profile of the pn junction as well as the size of the photodiode. The pinch-off voltage is lower in a smaller photodiode. A simple method that uses the lateral depletion of a photodiode for an estimate of the pinch-off voltage in small photodiodes is proposed, and is compared to the measured experimental data. Two constants are used to account for the doping profile and photodiode size. The measurement data shows the error of the estimation of the pinch-off voltage to be <0.05 V. 相似文献
13.
Pixel image lag in a 4-T CMOS image sensor is analyzed and simulated in a two-dimensional model.Strategies of reducing image lag are discussed from transfer gate channel threshold voltage doping adjustment,PPD N-type doping dose/implant tilt adjustment and transfer gate operation voltage adjustment for signal electron transfer.With the computer analysis tool ISE-TCAD,simulation results show that minimum image lag can be obtained at a pinned photodiode n-type doping dose of 7.0×10~(12) cm~(-2),an implant ... 相似文献
14.
CMOS图像传感器钳位光敏二极管夹断电压模型研究 总被引:1,自引:1,他引:0
A novel analytical model of pinch-off voltage for CMOS image pixels with a pinned photodiode structure is proposed. The derived model takes account of the gradient doping distributions in the N buried layer due to the impurity compensation formed by manufacturing processes; the impurity distribution characteristics of two boundary PN junctions located in the region for particular spectrum response of a pinned photodiode are quantitative analyzed. By solving Poisson's equation in vertical barrier regions, the relationships between the pinch-off voltage and the corresponding process parameters such as peak doping concentration, N type width and doping concentration gradient of the N buried layer are established. Test results have shown that the derived model features the variations of the pinch-off voltage versus the process implant conditions more accurately than the traditional model. The research conclusions in this paper provide theoretical evidence for evaluating the pinch-off voltage design. 相似文献
15.
A new sensitivity controllable pixel structure is proposed for CMOS active-pixel image sensor. The proposed pixel structure has a sensitivity control gate overlaid on the photodiode. The sensitivity of the pixel is controlled by the bias voltage of the control gate that forms a variable accumulation-mode MOS capacitor. The prototype sensor is fabricated with a 0.35-mum CMOS process and consists of 60 times 240 pixels with 5.6-mum pixel pitch. Measurement results show that the sensitivity of the photodiode can be controlled by a factor of 4. 相似文献
16.
17.
To overcome the limitation of low image signal swing range and long reset time in four Iransistor CMOS active pixel image sensor, a charge pump circuit is presented to improve the pixel reset performance. The charge pump circuit consists of two stage switch capacitor serial voltage doubler. Cross-coupled MOSFET switch structure with well close and open performance is used in the second stage of the charge pump. The pixel reset transistor with gate voltage driven by output of the pump works in linear region, which can accelerate reset process and complete reset is achieved. The simulation results show that output of the charge pump is enhanced from 1.2 to 4.2 V with voltage ripple lower than 6 inV. The pixel reset time is reduced to 1.14 ns in dark. Image smear due to non-completely reset is elIminated and the image signal swing range is enlarged. The charge pump is successfully embedded in a CMOS image sensor chip with 0.3 × 10^6 pixels. 相似文献
18.
Sungsik Lee Kyounghoon Yang 《Electron Device Letters, IEEE》2007,28(6):492-494
This letter presents a high dynamic range CMOS active pixel structure operating at a sub-1-V supply voltage, which is implemented using a standard 0.18-mum CMOS logic process. In order to improve the output voltage swing range and associated pixel dynamic range at a low supply voltage, a pMOS reset structure is incorporated into the pixel structure along with a photogate pixel structure based on the self-adaptive photosensing operation. At a low supply voltage of 0.9 V, the new pixel provides an output voltage swing range of 0.41 V and a high dynamic range of 86 dB, which is the highest among the reported pixel structures up to date operating at sub-1-V 相似文献
19.
提出了一种具有新型像素结构的大动态范围CMOS图像传感器,通过调整单个像素的积分时间来自适应不同的局部光照情况,从而有效提高动态范围。设计了一种低延时、低功耗、结构简单的新型pixel级电压比较器及基于可逆计数器的时间-电压编码电路。采用0.6μm DPDM标准数字CMOS工艺参数对大动态范围像素单元电路进行仿真,积分电容电压Vcint与光电流呈良好的线性关系,其动态范围可达126dB。在3.3V供电电压下,单个像元功耗为2.1μW。 相似文献