A novel superjunction MOSFET with improved ruggedness under unclamped inductive switching

The ruggedness of a superjunction metal–oxide semiconductor field-effect transistor (MOSFET) under unclamped inductive switching conditions is improved by optimizing the avalanche current path. Inserting a P-island with relatively high doping concentration into the P-column, the avalanche breakdown point is localized. In addition, a trench type P+ contact is designed to shorten the current path. As a consequence, the avalanche current path is located away from the N+ source/P-body junction and the activation of the parasitic transistor can be effectively avoided. To verify the proposed structural mechanism, a two-dimensional (2D) numerical simulation is performed to describe its static and on-state avalanche behaviours, and a method of mixed-mode device and circuit simulation is used to predict its performances under realistic unclamped inductive switching. Simulation shows that the proposed structure can endure a remarkably higher avalanche energy compared with a conventional superjunction MOSFET.     

一种新型的双波长光电高温计

基于黑体辐射原理,设计了一种可用于金属冶炼测温的双波长光电高温计。该高温计利用和钢水达到热平衡的石英玻璃窗作为发光体,实现浸入式测温,减少了环境干扰(如灰尘、水汽等)带来的误差。通过透镜、二向分光镜、窄带滤光片、光电转换器件实现了两路光信号的传输采集和转换。设计了以ADuC812为核心进行数据采集、信号处理、温度显示的二次仪表电路。实验给出了该高温计的稳定度,验证了该检测方法的可行性。     

恒功率输入恒流输出的电容器充电电源

常规恒流充电电源输入端的功率随着输出电压的升高而逐渐增加,充电结束时输入端的功率由最大值迅速降为0,不仅需要电网能够提供近2倍于平均值的峰值功率,还会造成电网电压的波动,特别是在重复频率与工频接近的大功率应用场合时,可能造成电网滤波系统的振荡,影响供电可靠性和干扰其他用电设备。提出了一种带有储能环节的电路拓扑,使得在对负载恒流充电期间,输入端的功率保持在平均功率水平。充分利用了串联谐振电路断续工作模式的特点,无需辅助变换器,仅通过双向开关对电流的控制,可将充电初期多余能量存储到储能环节,并在充电后期逐渐将此能量向负载释放,在充电启停时刻储能环节的净增能量为0。将上述拓扑电路添加到基于DC-link的恒流充电电源中,进行了分析和控制参数推导,并在输出电流8 A、最高输出电压5 kV的电源上进行了实验,结果表明：充电期间直流母线提供的电流基本稳定,幅值为常规方案中最大母线电流的一半左右。     

恒功率输入恒流输出的电容器充电电源

常规恒流充电电源输入端的功率随着输出电压的升高而逐渐增加,充电结束时输入端的功率由最大值迅速降为0,不仅需要电网能够提供近2倍于平均值的峰值功率,还会造成电网电压的波动,特别是在重复频率与工频接近的大功率应用场合时,可能造成电网滤波系统的振荡,影响供电可靠性和干扰其他用电设备。提出了一种带有储能环节的电路拓扑,使得在对负载恒流充电期间,输入端的功率保持在平均功率水平。充分利用了串联谐振电路断续工作模式的特点,无需辅助变换器,仅通过双向开关对电流的控制,可将充电初期多余能量存储到储能环节,并在充电后期逐渐将此能量向负载释放,在充电启停时刻储能环节的净增能量为0。将上述拓扑电路添加到基于DC-link的恒流充电电源中,进行了分析和控制参数推导,并在输出电流8 A、最高输出电压5 kV的电源上进行了实验,结果表明:充电期间直流母线提供的电流基本稳定,幅值为常规方案中最大母线电流的一半左右。     

A novel video-based microsphere localization algorithm for low contrast silica particles under white light illumination

On the basis of a brief review of four common image recognition algorithms for microspheres made of polystyrene or melamine resin, we present a new microsphere localization method for low-contrast silica beads under white light illumination. We compare both the polystyrene and silica procedures with respect to accuracy and precision by means of an optical tweezers setup providing CMOS video microscopy capability. By that we demonstrate that our new silica algorithm achieves a relative position uncertainty of less than ±1 nm for micron-sized microspheres, significantly exceeding the precision of the other silica approaches studied. Second, we present an advancement of our single microsphere tracking method to scenarios where two polystyrene, melamine resin or silica microspheres are in close-to-contact proximity. While the majority of the analysis algorithms studied generate artefacts due to interference effects under these conditions, we show that our new approach yields accurate and precise results.     

透射式照明系统的光学设计新方法

在各向同性的点光源系统中,利用光线在照明面上的高度与入射角的关系,用Zemax软件设计照度分布均匀的系统。给出了柯拉照明系统的设计实例。通过LightTools软件对其进行模拟和对实际光源系统进行测定,验证了这种设计方法的可行性。     

一个新的恒Lyapunov指数谱混沌吸引子与电路实现

通过对改进恒Lyapunov指数谱混沌系统进行进一步演变,并引入新的绝对值项,发现了一种新的混沌吸引子.首先,通过相图、Poincar映射、Lyapunov指数以及功率谱,证明该混沌吸引子的存在性.接着,分析研究了这种新型混沌吸引子的基本动力学行为.Lyapunov指数谱、分岔图和状态变量幅值演变的数值仿真说明,该系统存在全局线性调幅参数,在该参数的调整下,系统输出三维信号的幅度皆能得到线性调整,而系统保持相同的混沌吸引子与Lyapunov指数谱.最后,通过构建电路实现了该混沌系统,观察到相应的混沌吸引子,也验证了全局线性调幅参数的调幅作用,数值仿真与电路实现有很好的一致性.     

A novel pose and illumination robust face recognition with a single training image per person algorithm

In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.     

A novel asymmetric arrayed waveguide grating with different lengths of input/output slabs

A novel arrayed waveguide grating (AWG) with asymmetric configuration is proposed. In this configuration, the length of the output slab region, the width and the spacing of the output waveguides are unequal to the corresponding parts of the input ones. Compared to a conventional symmetric AWG, the asymmetric AWG proposed in this paper has a smaller size without degrading its performance The analytic method used in a conventional symmetric AWG is extended to the asymmetric AWG. A design example of an asymmetric AWG with low insertion loss, low channel crosstalk and wide bandwidth is presented.     

A novel deep submicron SiGe-on-insulator (SGOI) MOSFET with modified channel band energy for electrical performance improvement

In this paper, we present the unique features exhibited by a novel nanoscale SiGe-on-insulator metal-oxide-semiconductor field-effect transistor (MOSFET) with modified channel band energy. The key idea in this work is to modify the band energy in the channel for improving electrical performances. Graded Ge composition profile is employed in the channel that leads to call the proposed structure as GC-SGOI structure. Using two-dimensional two-carrier simulation we demonstrate that the GC-SGOI structure has higher saturation velocity in comparison with stepped (SC-SGOI) and uniform (UC-SGOI) germanium composition due to the high conduction and valence bands slopes by using graded Ge composition profile. Also, our results show that the GC-SGOI exhibit excellent properties not only higher mobility, drain current and saturation velocity but also hot electron degradation improvement and better reliability. Therefore, refer to the results, the GC-SGOI structure has superior performances in comparison with the SC- and UC-SGOI structures which leads to be a good candidate for VLSI circuits.     

脉冲加载下锥角绝缘子的激光辐照沿面闪络性能北大核心CSCD

通过搭建脉冲加载下的激光辐照沿面闪络实验平台,考察了锥角绝缘子受激光辐照时的真空沿面闪络性能。结果表明:不论是紫外光(266nm)还是可见光(532nm)辐照在阴极三相点或者样品中间,+45°锥角绝缘子构型的性能都要优于-45°锥角绝缘子,并且紫外辐照阴极三相点对沿面闪络电压的影响较大,因此在大型脉冲功率装置中应该避免射线对绝缘堆阴极三相点处的辐照。     

脉冲加载下锥角绝缘子的激光辐照沿面闪络性能

通过搭建脉冲加载下的激光辐照沿面闪络实验平台, 考察了锥角绝缘子受激光辐照时的真空沿面闪络性能。结果表明：不论是紫外光（266 nm）还是可见光（532 nm）辐照在阴极三相点或者样品中间, +45锥角绝缘子构型的性能都要优于－45锥角绝缘子, 并且紫外辐照阴极三相点对沿面闪络电压的影响较大, 因此在大型脉冲功率装置中应该避免射线对绝缘堆阴极三相点处的辐照。     

Study on a novel vertical enhancement-mode Ga2O3 MOSFET with FINFET structure

A novel enhanced mode(E-mode)Ga₂O₃ metal-oxide-semiconductor field-effect transistor(MOSFET)with vertical FINFET structure is proposed and the characteristics of that device are numerically investigated.It is found that the concentration of the source region and the width coupled with the height of the channel mainly effect the on-state characteristics.The metal material of the gate,the oxide material,the oxide thickness,and the epitaxial layer concentration strongly affect the threshold voltage and the output currents.Enabling an E-mode MOSFET device requires a large work function gate metal and an oxide with large dielectric constant.When the output current density of the device increases,the source concentration,the thickness of the epitaxial layer,and the total width of the device need to be expanded.The threshold voltage decreases with the increase of the width of the channel area under the same gate voltage.It is indicated that a set of optimal parameters of a practical vertical enhancement-mode Ga₂O₃ MOSFET requires the epitaxial layer concentration,the channel height of the device,the thickness of the source region,and the oxide thickness of the device should be less than 5×10¹⁶ cm^-3,less than 1.5μm,between 0.1μm-0.3μm and less than 0.08μm,respectively.     

部份相干光照明的随机孔屏衍射特性

本文从部份相干理论出发，导出了随机孔屏的衍射强度期望分布及涨落方差表达式；对随机孔屏的衍射特性作了较深入的分析；讨论了光源的空间特性对衍射图形的影响；研究表明：衍射强度的光场分布不仅与孔和屏的几何特性有关，还与光源的形状和大小密切相关，文中还指出：在特定明情况下，形状一定的小孔无论在数目还是尺寸上发生随机变化，都不会改变衍射场的强度期望分布和涨落方差分布。     

一种拖尾噪声环境中的稳健常数模盲均衡新算法

为了改善拖尾噪声环境中盲均衡器的性能,提出了一种稳健常数模盲均衡算法,修改了原常数模算法的误差函数,并进行非线性变换,有效地抑制了拖尾噪声的影响。采用浅海水声信道,在分别叠加高斯噪声与拖尾噪声的情况下,对算法进行了计算机仿真。结果表明:在高斯噪声环境中,新算法具有更快的收敛速度与更低的剩余码间干扰;在拖尾噪声环境中,原算法很不稳定,而新算法则性能稳健,能够稳定地收敛于较低的剩余码间干扰。     

A contrast variation of image speckle intensity under illumination of partially coherent light

Speckle patterns are formed by completely and partially coherent light at the image plane of a diffusing object. The general formula is derived for the contrast variation of the image speckle intensity distribution as a function of the spatial coherence of the illuminating light, the amplitude point-spread function of the optical imaging system and the statistical characteristic of the diffusing object. The effect of spatial coherence of the illuminating light on the contrast variations of the image speckle intensity distribution is theoretically evaluated under various statistical conditions of the diffusing object. The theoretical results are confirmed experimentally.     

A temporal analogy to imaging with coherent diffuse illumination

An experiment is described in which an amplitude modulated electrical signal, having a spectrum too broad to pass through a narrow band pass filter, is passed when random phase modulation precedes the amplitude modulation and the resulting signal is envelope detected. This technique is analogous to the case of diffuse illumination in an imaging system.     

一种带可调光照部分的专用彩色图像处理系统

介绍了肺癌介入治疗模拟实验的专用彩色图像处理系统 ,硬件由可调光照部分、CCD摄像头、视频采集卡和微机四大部分构成。软件不仅可以进行一般的数字图像处理 ,而且针对肺癌介入治疗模拟实验中的特殊要求 ,设计了比例测量、导管口跟踪等专用功能。该系统除了用于肺癌介入治疗模拟实验 ,还可用做指导临床介入治疗 ,具有乐观的应用前景。     

A gate enhanced power U-shaped MOSFET integrated with a Schottky rectifier

An accumulation gate enhanced power U-shaped metal-oxide-semiconductor field-effect-transistor(UMOSFET) integrated with a Schottky rectifier is proposed.In this device,a Schottky rectifier is integrated into each cell of the accumulation gate enhanced power UMOSFET.Specific on-resistances of 7.7 m.mm 2 and 6.5 m.mm 2 for the gate bias voltages of 5 V and 10 V are achieved,respectively,and the breakdown voltage is 61 V.The numerical simulation shows a 25% reduction in the reverse recovery time and about three orders of magnitude reduction in the leakage current as compared with the accumulation gate enhanced power UMOSFET.     

A 3D SiC MOSFET with poly-silicon/SiC heterojunction diode

A three-dimensional(3D)silicon-carbide(SiC)trench metal-oxide-semiconductor field-effect transistor(MOSFET)with a heterojunction diode(HJD-TMOS)is proposed and studied in this work.The SiC MOSFET is characterized by an HJD which is partially embedded on one side of the gate.When the device is in the turn-on state,the body parasitic diode can be effectively controlled by the embedded HJD,the switching loss thus decreases for the device.Moreover,a highly-doped P+layer is encircled the gate oxide on the same side as the HJD and under the gate oxide,which is used to lighten the electric field concentration and improve the reliability of gate oxide layer.Physical mechanism for the HJD-TMOS is analyzed.Comparing with the conventional device with the same level of on-resistance,the breakdown voltage of the HJD-TMOS is improved by 23.4%,and the miller charge and the switching loss decrease by 43.2%and 48.6%,respectively.