片上集成光电微能源工艺兼容性及器件特性研究

根据暂存式光电微能源系统组成器件的制备工艺特点,提出了基于SOI晶片的光电微能源片上集成方案。主要工艺包括绝缘沟槽刻蚀、离子注入、氧化等,具有较好的制备工艺兼容性。另外,根据片上集成方案,对器件特性进行了研究。结果表明,光伏电池的转换效率为9.7%,NMOS管阈值电压、漏极反向击穿电压VT分别为0.98 V和31.97 V,NPN三极管的电流放大倍数、集电极-发射极之间击穿电压约为83 V和12 V。各器件特性满足系统工作要求,集成方案具有较好的可行性。     

The evolution of standard cell libraries for future technology nodes

Evolvable Hardware has been a discipline for over 15 years. Its application has ranged from simple circuit design to antenna design. However, research in the field has often been criticised for not addressing real world problems. Intrinsic variability has been recognised as one of the major challenges facing the semiconductor industry. This paper describes an approach that optimises designs within a standard cell library by altering the transistor dimensions. The proposed approach uses a Multi-objective Genetic Algorithm to optimise the device widths within a standard cell. The designs are analysed using statistically enhanced transistor models (based on 3D-atomistic simulations) and statistical Spice simulations. The goal is to extract high-speed and low-power designs, which are more tolerant to the random fluctuations present in current and future technology nodes. The results show improvements in both the speed and power of the optimised standard cells and that the impact of threshold voltage variation is reduced.     

基于光学微腔的MOEMS微位移传感器

该MOEMS微位移传感器是一种基于光波导环形谐振腔的悬臂梁式传感器,通过一系列的微加工技术集成制造在SOI材料上.光学微腔是一种新型的光学谐振腔,当其在回音廊模式下(WGM)共振时可以检测到规则的透射谱图,该传感器通过测量透射谱的偏移来确定位移量.利用有限元分析法可以得到悬臂粱结构的最佳尺寸参数,利用时域有限差分方法(FDTD)可以得到环形腔投射谱的偏移特性.当使用跑道型谐振腔时,该新型传感器最高可以探测到10nm左右的位移量.     

A Large Dynamic Range Floating Memristor Emulator With Equal Port Current Restriction

In this paper, a large dynamic range floating memristor emulator(LDRFME) with equal port current restriction is proposed to be achieved by a large dynamic range floating voltage-controlled linear resistor(VCLR). Since real memristors have not been largely commercialized until now, the application of a LDRFME to memristive systems is reasonable. Motivated by this need, this paper proposes an achievement of a LDRFME based on a feasible transistor model. A first circuit extends the voltage range of the triode region of an ordinary junction field effect transistor(JFET). The idea is to use this JFET transistor as a tunable linear resistor. A second memristive non-linear circuit is used to drive the resistance of the first JFET transistor. Then those two circuits are connected together and, under certain conditions, the obtained "resistor" presents a hysteretic behavior,which is considered as a memristive effect. The electrical characteristics of a LDRFME are validated by software simulation and real measurement, respectively.     

The SOI DAWN process for three-dimensional silicon micromachining and its applications

A DRIE assisted wet anisotropic bulk micromachining (DAWN) process is demonstrated to fabricate various three-dimensional MEMS devices on a silicon-on-insulator (SOI) wafer. This SOI DAWN process can realize thin film structures, reinforced (thin film) structures, and thick structures with totally different mechanical characteristics. Various passive and active mechanical components, including flexible springs, rigid structures, and actuators, have been fabricated using the SOI DAWN process and have been further integrated to create MEMS devices which are flexible as well as movable in both in-plane and out-of-plane directions. This SOI DAWN process has been successfully applied to produce various multi-DOF devices made of single crystal silicon (SCS).     

基于BOE硅腐蚀现象的硅纳米线制作

介绍一种硅纳米线制作方法.在SOI顶层硅上制作硅纳米梁,通过离子注入形成pnp结构,利用新发现的没有特殊光照时BOE溶液腐蚀pn结n型区域现象,结合BOE溶液氧化硅腐蚀,实现硅纳米线制作.制作完全采用传统MEMS工艺,具有工艺简单,成本低,可控,可靠性好,可批量制作等优点.利用该方法制作出了厚50 nm,宽100 nm的单晶硅纳米线,制作的纳米线可用于一维纳米结构电学性能研究、谐振器研究等.     

Using a game engine for VR simulations in evacuation planning.

Researchers who want to use virtual reality-based simulations in their work must address some important requirements. Simulations require a good 3D graphical rendering capability. For realistic results, they must also consider the effects of physical laws, such as gravity and collision forces. A software platform that meets these requirements can serve a broad range of science and technology applications, but developing an entire platform is hard work itself. In this article, we present our use of a game engine for virtual simulations of building evacuations in emergency situations. We have modeled a real IEN building in 3D to perform preliminary evacuation tests, prior to real ones, and thus support evacuation planning. Nuclear plants represent just one of many environments where virtual simulations might be the best or only means of evaluating situations that are too dangerous to simulate in real environments-for example, in the presence of fire and smoke or radioactive or chemical contamination.     

Lattice Boltzmann simulation of lid-driven swirling flow in confined cylindrical cavity

Lid-driven swirling flow in a confined cylindrical cavity is investigated using lattice Boltzmann equation (LBE) method. The steady, 3-dimensional flow is examined at different aspect (height-to-radius) ratios and Reynolds numbers. The LBE simulations are carried out using the multiple-relaxation-time method. The LBE simulation results are compared with the results of a finite volume solution of Navier-Stokes equations and with published experimental data. Numerical results are presented for cylindrical cavities with two aspect ratios of 1.5 and 2.5, and three Reynolds numbers of 990, 1010 and 1290. Effects of the aspect ratio and Reynolds number on the size, position and breakdown of the central recirculation bubble, together with the flow pattern in the cavity, are determined. Detailed topological features of the flow, such as, (1) structure and breakdown of the vortex along the axis, (2) azimuthal component of vorticity, and (3) circulation strength of flow about the axis are investigated and compared with previous findings from experiments and theory.The predicted results from LBE simulations are consistent with experiments and theory. Steady results reveal the occurrence of a breakdown bubble in agreement with the regime diagram due to Escudier. The vortex breakdown around a region may be characterized by a change in sign of the azimuthal vorticity near such locations. Investigations are carried out on the characteristics of angular momentum when the vortex breakdown occurs. The theoretical criterion for vortex breakdown to occur, as proposed by Brown and Lopez is verified using the numerical data obtained from the simulations.     

Electrical characterization of a RF power transistor ceramic package including multiple wirebonds

This article presents an approach for modeling of RF power transistor packages including bondwires. The approach is based on measurements of a real package in which the transistor chip was replaced with a 2‐port of known parameters and connected to the package leads with multiple parallel wirebonds. Using the measurement results, an equivalent circuit of the package is constructed. The response of the circuit is then compared to measurements and results obtained through full‐wave electromagnetic modeling to reveal good agreement. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Straightforward modeling of dynamic I–V characteristics for microwave FETs

This work presents a straightforward approach aimed at modeling the dynamic I–V characteristics of microwave active solid‐state devices. The drain‐source current generator represents the most significant source of nonlinearity in a transistor and, therefore, its correct modeling is fundamental to predict accurately the current and voltage waveforms under large‐signal operation. The proposed approach relies on using a small set of low‐frequency time‐domain waveform measurements combined with numerical optimization‐based estimation of the nonlinear model parameters. The procedure is applied to a gallium nitride HEMT and silicon FinFET. The effectiveness of the modeling procedure in terms of prediction accuracy and generalization capability is demonstrated by validation of the extracted models under operating conditions different than the ones used for the parameters estimation. Good agreement between measurements and model simulations is achieved for both technologies and in both low‐ and high‐frequency range. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:109–116, 2014.     

Electrical performance of static induction transistor with transverse structure

A novel static induction transistor with transverse surface gate structure was designed and successfully fabricated in this paper. Its basic electrical characteristics and frequency performance was investigated in depth. The optimum technological parameters such as source-gate space and epitaxial layer thickness for obtaining excellent frequency performance and high blocking voltage capacity were represented and discussed in detail. The main advantage of this work is that the performances of device were improved with simple structure and technological processes. The experimental and simulated results demonstrate the trans-conductance g_m and gate-source breakdown voltage BV_GS of the transverse type SIT increase from 60 to 87 ms and 20 to 26 V, respectively, in addition to obtaining higher than 100 MHz operating frequency under relatively simple technology processes compared with those of traditional vertical SIT.     

Technology independent circuit sizing for standard cell based design using neural networks

This paper presents a neural network (NN) approach for modeling the time characteristics of fundamental gates of digital integrated circuits that include inverter, NAND, NOR, and XOR gates. The modeling approach presented here is technology independent, fast, and accurate, which makes it suitable for circuit simulators. Firstly transient simulations were done in order to obtain delay times for different transistor sizes and different load capacitances using AMIS 1.5 μm, TSMC 0.25 μm and TSMC 0.18 μm technology parameters with HSPICE. These delay time results constitute the inputs of NN while the outputs are transistor sizes. Then, two neural network structures, multilayer perceptron (MLP) and general regression neural network (GRNN), were compared to estimate the transistor sizes. MLP achieved 91 acceptable results through 120 test data where GRNN had 77. The important thing is that the NN is able to generalize the input–output mapping and estimates the outputs for new data which were not applied to the NN for training before. As a conclusion, fundamental gates used for standard cell based VLSI design can be sized for desired delay times using neural networks without knowing SPICE technology parameters.     

Thermal analysis of microwave GaN‐HEMTs in conventional and flip‐chip assemblies

Temperature rising which originates from self‐heating degrades the electrical characteristics, reliability, and lifetime of high‐power GaN‐HEMTs. In this article, a systematic analytical approach for thermal evaluation of microwave GaN‐HEMTs is constructed through combining and scrutinizing some of the basic static thermal analysis methods to provide a deeper insight into the process of the channel temperature rising and self‐heating with a much lower computational burden. The proposed systematic thermal analysis has been applied to two different assembly methods: conventional mounting and flip‐chip mounting. Although the mathematical and empirical equations used are simple enough to save time, the effects of several phenomena and different conditions on the channel temperature have been taken into account. These include heat crowding phenomenon, the effect of temperature‐dependent thermal conductivity of the transistor constituent materials, transistor geometry, die‐attach material properties, and bump dimensions. To validate the accuracy of the calculations, all the analytical analyses are followed by 3D thermal simulations in ANSYS software. The simulation results confirm the accuracy of the analytical calculations.     

一种用于ADC模拟集成电路设计和分析的MOS晶体管模型

本文提出了一个适合模拟集成电路设计和分析的金属氧化物场效应晶体管模型。它以晶体管反型系数if为基础，表达式具有简洁的形式和良好的精度，并通过一个ADC电路中经常出现的简单共源极放大器的设计过程和仿真结果的对比分析，解释说明这个模型的具体应用。     

Response time assessment in forest fire spread simulation: An integrated methodology for efficient exploitation of available prediction time

This work details a framework developed to shorten the time needed to perform fire spread predictions. The methodology presented relies on a two-stage prediction strategy which introduces a calibration stage in order to relieve the effects of uncertainty on simulator input parameters. Early assessment of the response time and quality of the results obtained constitute a key component in this method. This automatic and intelligent process of identification of lengthy simulations that slow down the course of the predictions presents a very high hit ratio. However, discarding certain simulations from the adjustment process (based on evolutionary algorithms) could lead to loss of accuracy in our predictions. A strong statistical study to analyze the impact of this action on our final predictions is reported. This study is based on a real fire which burnt 13,000 ha in the region of Catalonia (north-east of Spain) in the summer of 2012.     

基于SOI硅片研制新型P~+-I-N~+双注入磁敏差分电路

阐述基于SOI硅片制造新型P+ I N+双注入磁敏差分电路的设计原理和制造工艺。构成新型P+ I N+双注入磁敏差分电路的磁敏三极管的复合区采用MEMS中的各向异性腐蚀技术进行设置,给出了这种复合区的复合机理。实验结果表明:此种三极管具有磁灵敏度高、噪声低和可靠性高的特点。因此,由这种新型磁敏三极管构成的差分电路具有温度漂移小的优点。     

Global model for high power microwave breakdown at high pressure in air

Global models (GM) have proven a key tool for modeling low temperature plasmas for materials processing due to simplicity and speed. However, a GM requires specification of the electron energy distribution function (EEDF). The assumption of a Maxwellian EEDF leads to inaccurate power absorption and reaction rate coefficients and results in errors in plasma parameter prediction in high power microwave (HPM) driven discharges. In this work, a GM was developed with a pressure-independent enhanced EEDF and enhanced power absorption model to improve fidelity for modeling HPM breakdown, and extended to two decades in applied frequency. The GM is applied to HPM breakdown in air at high pressure and over a wide frequency range, and results compared well with PIC-MCC simulations as well as experimental data.     

BRDF Representation and Acquisition

Photorealistic rendering of real world environments is important in a range of different areas; including Visual Special effects, Interior/Exterior Modelling, Architectural Modelling, Cultural Heritage, Computer Games and Automotive Design. Currently, rendering systems are able to produce photorealistic simulations of the appearance of many real‐world materials. In the real world, viewer perception of objects depends on the lighting and object/material/surface characteristics, the way a surface interacts with the light and on how the light is reflected, scattered, absorbed by the surface and the impact these characteristics have on material appearance. In order to re‐produce this, it is necessary to understand how materials interact with light. Thus the representation and acquisition of material models has become such an active research area. This survey of the state‐of‐the‐art of BRDF Representation and Acquisition presents an overview of BRDF (Bidirectional Reflectance Distribution Function) models used to represent surface/material reflection characteristics, and describes current acquisition methods for the capture and rendering of photorealistic materials.     

大攻角导弹DDFC变结构解耦控制器设计

研究空空导弹快速响应优化问题,空空导弹大攻角飞行时,由于出现非对称涡及涡破裂现象,导致强烈的通道间耦合并呈现非线性特性,影响速度特性。为解决上述问题,设计了一种直接动态反馈补偿理论(Direct Dynamics Feedback Com-pensation,DDFC)控制策略的解耦控制器。首先建立了具有大攻角导弹耦合特性非线性数学模型,并直接动态反馈补偿理论给出了一种解耦控制策略,结合滑模变结构控制理论设计了解耦控制器。最后,对控制系统进行了数值仿真,仿真结果验证了改进方法的可行性。