基于UMV的重构图像扩展算法及VLSI实现

在AVS视频解码系统中,针对运动补偿所需的参考宏块出界导致视频解码效率降低的问题,提出一种新型图像边界扩展算法重构了出界参考宏块,以获得相应运动向量进行完善的运动补偿。该算法基于视频解码系统流水线设计要求,同时考虑消除中间存储的需求,对图像数据进行分析,依据图像数据的不同类型和位置进行边界宏块像素的有序扩展,并采用二维存储机制提高效率,使得在运动补偿中实现了图像无限制运动向量(UMV),优化了图像运动补偿效果,提高了视频的解码效率。该算法采用Verilog HDL语言描述,经EDA软件仿真、综合及FPGA验证表明:该算法能够在图像运动补偿中获得出界参考宏块的运动向量,实现图像运动补偿的优化,本模块打开UMV后综合的芯片面积仅增加面积1.5%,而AVS视频解码系统采用UMV比不采用UMV解码效率明显提高。     

大尺寸像素电荷转移的优化方法

为了提高CMOS图像传感器大尺寸像素的电荷转移效率,消除图像拖尾,通过对像素内电荷转移的RC模型分析,提出一种优化电荷转移的方法。从工艺和版图两方面进行优化,工艺方面是在N埋层的形成步骤中增加一步P型杂质注入,使光电二极管内存在电场,增强电荷转移;版图方面是优化光电二极管的版图为U型,使传输栅伸进光电二极管内尽量长,减少RC模型的传输级数,提高电荷转移效率。与传统像素相比,工艺和版图的优化使电荷转移效率分别提高了2倍和3.3倍,转移时间也分别缩短到传统像素结构的26%和30%左右。对传统像素结构进行工艺和版图同时优化则使电荷转移效率提高了9.5倍。     

含MDAC 10位20Mps流水线ADC设计

设计10位20Mps流水线模数转换器,它具有高速度高分辨率的优点.其核心模块MDAC集数模转换、减法、余差放大和采样保持功能于一身,简化电路结构,提高模数转换器的性能.分析电容失配引入的误差,并给出减小误差的方法,微分非线性和积分非线性的模拟结果.     

正方形截面长隧道内壁爆炸超压分布规律

以爆炸力学为理论基础,利用有限元软件ANSYS/LS-DYNA,定性地研究了正方形截面长隧道内爆炸引起的内壁上超压分布规律.按其工作原理,预先应用ANSYS/LS-DYNA软件建立宽、高均为2 m的正方形截面长隧道模型,在隧道不同结点处分别布置基准药量W0=0.205 kg的炸药,采集由其爆炸而引起的内壁各结点上超压峰值和超压到达时间的数据,并且借助于绘图软件origin制成包络图,研究了隧道内壁超压的分布规律.研究结果为工程结构抗爆设计提供了参考,因而具有很好的工程应用前景.     

A linear stepping PGA used in CMOS image sensors

A low power linear stepping digital programming gain amplifier (PGA) is designed for CMOS image sensors. The PGA consists of three stages with gain range from one to nine. The gain is divided into four regions and each range has 128 linear steps. Power consumption of the PGA is saved by good tradeoff between variation of amplifier feedback coefficient, pipeline stages and gain regions. With thermometer-binary mixed coding and linear pipeline gain stepping, the load capacitance keeps constant when the gain of one stage is changed. The PGA is designed in the SMIC 0.18μm process. Simulation results show that the power consumption is 3.2 mW with 10 bit resolution and 10 MSPS sampling rate. The PGA has been embedded in a 0.3 megapixel CMOS image sensors and fabricated successfully.     

A charge pump for driving CMOS active pixel reset

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.     

Implementation of automatic white-balance based on adaptive-luminance

A novel automatic white-balance algorithm based on adaptive-luminance is proposed in this paper. This algorithm rede- fines the gray pixels region, which can filter the gray pixels accurately. Furthermore, with the relations between gray pixels’ luminance with standard light source and their chroma Cb, Cr shifts with other color temperatures, the algorithm estab- lishes the equations between the captured pixels and the original ones, which can estimate the gains of RGB channels exactly. To evaluate the prop...     

一种获得四管CMOS图像传感器像素夹断电压的方法

提出了一种测试四管CMOS图像传感器像素夹断电压的方法。该方法是基于像素中势阱结构的变化能够对图像信号散粒噪声产生影响的假设。实验结果测得的夹断电压与理论预测相一致。该技术提供的实验方法不仅能够帮助设计四管CMOS图像传感器光电二极管的结构,而且也能优化像素生产工艺。     

基于色温估计的自动白平衡算法研究

为了解决现有灰度世界算法在拍摄大面积色块时的失效问题,提出一种在RGB色度空间的基于色温估计的自动白平衡算法。首先确定不同的光源在RjGBjG空间中的分布规律;然后根据图像中像素原始数据R／G、B／G的值确定光源信息,得到相应R、G和B增益值;最终实现白平衡调整。实验结果表明,在图形颜色信息比较丰富时,算法处理结果较灰...