Distributed current-mode image processing filters

Presented is a new design method for distributed focal plane image processing, which allows complementary metal oxide semiconductor (CMOS) implementation of two-dimensional, reconfigurable, image-processing kernels at the pixel level.     

双CMOS图像传感器的抗晕光图像采集系统设计

为解决CMOS图像传感器采集图像时产生晕光问题,提出一种CMOS图像传感器的抗晕光图像采集系统设计方案.TMS320C6414采用阈值化分割算法,对两路图像数据进行剪裁,汲取各自图像的优点,输出一路比较清晰的图像信息.其效果相当于扩大了CMOS图像传感器的动态范围,从而达到抗晕光的效果.     

Design consideration of p-well structure for solid-state image sensors

The p-well structure has been widely used in solid-state image sensors to suppress blooming and smear. This structure, however, suffers from saturation-level shading, flicker, and saturation-level fixed pattern noise. This work clarifies that the p-well potential sway, due to transfer pulse feeding, brings about the shading and the flicker, and the impurity fluctuation in the silicon substrate causes the saturation-level fixed pattern noise. To eliminate the problems, new structures and new driving modes are proposed. As a result, the shading is reduced to a practically negligible level, and the flicker and the fixed pattern noise are completely suppressed.     

CMOS image sensors

In this article, we provide a basic introduction to CMOS image-sensor technology, design and performance limits and present recent developments and future directions in this area. We also discuss image-sensor operation and describe the most popular CMOS image-sensor architectures. We note the main non-idealities that limit CMOS image sensor performance, and specify several key performance measures. One of the most important advantages of CMOS image sensors over CCDs is the ability to integrate sensing with analog and digital processing down to the pixel level. Finally, we focus on recent developments and future research directions that are enabled by pixel-level processing, the applications of which promise to further improve CMOS image sensor performance and broaden their applicability beyond current markets.     

Review of CMOS image sensors

The role of CMOS Image Sensors since their birth around the 1960s, has been changing a lot. Unlike the past, current CMOS Image Sensors are becoming competitive with regard to Charged Couple Device (CCD) technology. They offer many advantages with respect to CCD, such as lower power consumption, lower voltage operation, on-chip functionality and lower cost. Nevertheless, they are still too noisy and less sensitive than CCDs.Noise and sensitivity are the key-factors to compete with industrial and scientific CCDs. It must be pointed out also that there are several kinds of CMOS Image sensors, each of them to satisfy the huge demand in different areas, such as Digital photography, industrial vision, medical and space applications, electrostatic sensing, automotive, instrumentation and 3D vision systems.In the wake of that, a lot of research has been carried out, focusing on problems to be solved such as sensitivity, noise, power consumption, voltage operation, speed imaging and dynamic range. In this paper, CMOS Image Sensors are reviewed, providing information on the latest advances achieved, their applications, the new challenges and their limitations. In conclusion, the State-of-the-art of CMOS Image Sensors.     

Signal readout in CID image sensors

An analysis is presented that relates the photogenerated charge collected in one element of a charge-injection device imaging array to the voltage readout corresponding to that element. A linear relationship results when a voltage sensing amplifier is used. Crosstalk is found to occur, however, when a portion of the array is illuminated above saturation. This effect was demonstrated in a CID imager. A charge-amplifier scheme is presented that eliminates this type of crosstalk as well as some fixed pattern noise.     

Design techniques for high-resolution current-mode sigma-deltamodulators

This paper describes techniques for the design of high-resolution oversampling analog-to-digital converters based on current memories. A key point is the reduction of nonlinearities, in particular those introduced by the current switches. A current-memory cell with very high precision and linearity has been designed and used in an experimental third-order Σ-δ modulator in a 0.8-μm digital CMOS process. A linearity of better than 14 b and a maximum signal-to-noise+distortion ratio (SNDR) of 80 dB has been measured for an oversampling ratio (OSR) of 64     

VLSI implementation of receptive fields with current-mode signal processing for smart vision sensors

Most of the early vision processes in vertebrate vision systems can be modelled by receptive fields in the retina. Building silicon retina ICs has been attempted in the past, but they have not reached a satisfactory conclusion due to technology constraints. Targeting a wafer-size smart vision sensor, we focus in this paper on researching the VLSI implementation of different receptive fields with dedicated functions. The microelectronic receptive field (MERF) is defined as a functional block of the larger system, performing a preprogrammed operation on visual input signals. The main component of MERF's are analog processors operating in current domain that use current signals from photodetectors to produce desired image processing function and to convert their outputs into frequency mode signals. Results from VLSI chips with various integrated implementations of receptive fields are presented.     

有源功率因数校正控制电路的设计

有源功率因数校正控制器主要应用于电子镇流器、LED灯驱动和AC/DC电源中。本文结合当前先进照明电源的要求,实现了微功耗启动,并且有静态电流和工作电流小、功耗低的特点,可以方便地使芯片工作在省电模式。本设计采用内置乘法器,使功率因数在大的输入电压以及负载范围内接近于1。本电路设计了动态和静态两种过压保护机制,能安全处理启动和负载断开时产生的过电压。同时根据该类型电路的应用特点,增加了很多保护功能,保证各类照明驱动电源安全稳定地工作。     

Combined image signal processing for CMOS image sensors

An efficient image signal processing structure is proposed for CMOS image sensors to achieve low area and power consumption. In the proposed structure, the gamma correction block is moved to the front to merge several image signal processings into one block. An efficient compensation scheme is also proposed to reduce the errors caused by the moving of the nonlinear gamma correction. Experimental results show that the proposed structure reduces area and power consumption by 23.8 and 31.1%, respectively.     

Analogue MOS current-mode circuits for three-dimensional integrated smart image sensor

An image processing technique using analogue MOS current-mode circuits is presented. This approach is of interest in smart image sensors based on three-dimensional (or multi-layered) VLSI structures. High-performance smart image sensors with high resolution can be realised because the number of transistors required for image processing in each pixel is greatly reduced.<>     

CMOS image sensors: State-of-the-art

This paper gives an overview of the state-of-the-art of CMOS image sensors. The main focus is put on the shrinkage of the pixels : what is the effect on the performance characteristics of the imagers and on the various physical parameters of the camera ? How is the CMOS pixel architecture optimized to cope with the negative performance effects of the ever-shrinking pixel size ? On the other hand, the smaller dimensions in CMOS technology allow further integration on column level and even on pixel level. This will make CMOS imagers even smarter that they are already.     

Static induction transistor image sensors

New image sensors, based on the operational principle of static induction transistor (SIT), are described in this paper. Two operational modes of SIT image sensors are described here. One is the electron-accumulation mode in which electrons are stored in the floating-cell region and another is the electron-depletion mode in which electrons are removed from the floating-cell region in response to optical input. The electron-depletion mode is superior to the electron-accumulation mode in the charge retention characteristics, its temperature dependence, and the operational tolerancy. The described SIT image sensors, which utilize the vertically configured SITM structure, are very promising for application in very-large-area image converters due to high-speed high-packing density, and wide dynamic range, and especially due to extremely low power dissipation.     

Charge detection modeling in solid-state image sensors

Solid-state image sensors continue to find many applications as fabrication technology improves. Due in part to the relatively small role that image sensors have played in the semiconductor world, there exists very little experience in performance modeling of this class of devices. In this paper we discuss a three-dimensional model of the image sensor responsivity. Responsitivity is simply the amount of charge detected by the image sensor divided by the input photon energy. We discuss the fundamental aspects of charge detection and formulate and solve the appropriate model. We find good agreement between this model and experimental data.     

基于跨导放大器的电流模式积分单元的设计

在集成电路系统中,各种模拟功能的电流单元都是由基本的电流模单元组成。跨导放大器是电流模电路的基本单元。基于跨导放大器的电流模积分器可以实现电流到电流的积分转换。同时可应用于各种集成滤波电路的设计。在此采用0．18ptmCMOS仿真工艺,使用共源共栅结构设计一款供电电压为1．8V的高增益低功耗的跨导放大器,采用具有PTAT基准电流源的偏置电路,使用HSpice进行优化设计,并将此放大器应用于电流模式积分单元的电路仿真。     

Charge-transfer readout and white-video-defect suppression in X-Y image sensors

A method of detecting photosignals in solid-state image sensors is described. The technique employes bucket-brigade charge-transfer readout of a modified X-Y imaging array. This concept is further developed to cover its use in a single-pellet tricolor image sensor. A natural extension of this same bucket-brigade fan-in circuit leads to a method of mitigating the effects of white video defects in both solid-state image sensors and beam-scanned tubes.     

可调谐的电流模式五阶椭圆低通滤波器设计

用多输出电流控制传送器(multiple outputs current controlled conveyor II,CCCII±)实现的串联FDNR-R等效电路为积木块,设计出了电流模式五阶椭圆低通滤波器.电路中所有电容接地,且滤波参数能实现电子调谐,这从集成的观点来看是非常重要的.     

Characterization and deblurring of lateral crosstalk in CMOS image sensors

Lateral crosstalk in CMOS imaging arrays deter effective utilization of small pixel sizes (e.g., < 5.0 /spl mu/m /spl times/ 5.0 /spl mu/m) now permitted by technology scaling. A simple measurement setup for empirical characterization of lateral crosstalk in CMOS image sensors is presented. A demonstration of deblurring operations based on the obtained blur model of lateral crosstalk is also provided. Several well-known linear deconvolution filters are employed in the demonstration. The tradeoffs in sharpness restoration, high-frequency noise amplification, and the intensity clipping effect in the design of linear deblurring operation for the application of lateral crosstalk are illustrated.