Broadband Wireless Access Solutions - Progressive Challenges and Potential Valueof Next Generation Mobile Networks

The growth in mobile communication will accelerate over the next years. Today most of the mobile subscribers use cellular services only. But this will change in the near future towards broadband wireless access services like WiFi and WiMAX. This paper describes a fundamental overview of the broadband wireless access technologies and outlines the market view, major trends and introduces OFDM technologies. New developments for integration of broadband wireless access into the operators' infrastructure are also discussed.     

Sputtered metal lift-off for grating fabrication on InP based optical devices

Sputtered metal gratings have been realized using lift-off process based on bilayer resist electron beam lithography (EBL). The lithography mask is composed of PMMA (poly(methylméthacrylate)) layer deposited under HSQ (hydrogen silsesquioxane) inorganic resist. EBL is performed in HSQ, whereas PMMA is used to ease final lift-off. We demonstrate the possibility of patterning by lift-off metals with different sputtering yields and deposition conditions. Gratings with period of 200 nm and filling factor of 50% are obtained.     

用于先进的双嵌入和栓工艺的低缺陷钨CMP高性价比浆料(英文)

介绍了用于钨双嵌入和钨栓CMP工艺的新型CMP3200TM氧化铝浆料,测试证明,这种浆料在110nm技术节点的钨CMP工艺应用中取得了理想的效果。通过对氧化铝粒子制造工艺的有效控制,获得了可满足110nm技术节点双嵌入和栓层钨CMP工艺要求的低缺陷率,高性价比的氧化铝蛐硝酸铁浆料。从而在价格竞争激烈的半导体制造领域,特别是代工市场引起了业界越来越多的关注。     

Time-domain surface impedances of lossless Debye media

In a previous paper, a surface impedance formalism was given. Its application to interfaces modelling between homogeneous and frequency dependent media, was of great interest in the finite difference timedomain (fdtd) codes. In this paper, an extension of the method to dispersive media is presented. Applying this formalism to lossless Debye medium, the analytical expressions of the time- domain surface impedances are given. The implementation in a fdtd code permits then a numerical verification of the results in relation to the Fresnel method.     

Winner-Takes-All Associative Memory: A Hamming Distance Vector Quantizer

We present a design methodology for mapping neuralyinspired algorithms for vector quantization, into VLSI hardware.We describe the building blocks used: memory cells, current conveyors,and translinear circuits. We use the basic building blocks todesign an associative processor for bit-pattern classification;a high-density memory based neuromorphic processor. Operatingin parallel, the single chip system determines the closest match,based on the Hamming distance, between an input bit pattern andmultiple stored bit templates; ties are broken arbitrarily. Energyefficient processing is achieved through a precision-on-demandarchitecture. Scalable storage and processing is achieved througha compact six transistor static RAM cell/ALU circuit. The singlechip system is programmable for template sets of up to 124 bitsper template and can store up to 116 templates (total storagecapacity of 14 Kbits). An additional 604 bits of auxiliary storageis used for pipelining and fault tolerance re-configuration capability.A fully functional 6.8 mm by 6.9 mmchip has been fabricated in a standard single–poly, double–metal2.0µmn–well CMOS process.     

Cold-cavity vectorial eigenmodes of VCSELs

An analytical approximate solution of Maxwell's equations for the cold-cavity eigenmodes of cylindrical etched air-post vertical-cavity surface-emitting lasers (VCSELs) is presented. In radial and azimuthal directions, the modes correspond to the hybrid modes of cylindrical optical waveguides. A vectorial transform matrix approach is derived which takes into account coupling of bound eigenmodes in VCSEL structures. The method is illustrated for the case of noncoupled modes and the corresponding simplified transform matrix approach is used to calculate the field profiles in longitudinal direction and predict the resonance wavelengths for the VCSEL eigenmodes. Although approximate, the resulting eigenmodes may be viewed as a useful alternative to full numerical solutions, especially with regard to future more comprehensive modeling of VCSELs     

"国家点火装置"开始运转

“国家点火装置”计划约在15年前提出设想,现在这个装置正在建造,其初始运转十分成功,超出每个人的预计。在第一批四束激光运转中,激光系统的各个方面,从光束质量到能量结构,都符合设计规格。最终它将有192个光束．其已完成的2％的光束发射．已产生世界最高的激光能量。     

Design aspects of MOS-controlled thyristor elements: technology,simulation, and experimental results

2.5-kV thyristor devices have been fabricated with integrated MOS controlled n⁺-emitter shorts and a bipolar turn-on gate using a p-channel DMOS technology. Square-cell geometries with pitch variations ranging from 15 to 30 μm were implemented in one- and two-dimensional arrays with up to 20000 units. The impact of the cell pitch on the turn-off performance and the on-state voltage was studied for arrays with constant cathode area as well as for single-cell structures. By realizing MOS components with submicrometer channel lengths, scaled single cells are shown to turn off with current densities of several kiloamperes per square centimeter at a gate bias of 5 V. In the case of multi-cell ensembles, turn-off performance is limited due to inhomogeneous current distribution. Critical process parameters as well as the device behavior were optimized through multidimensional numerical simulation     

电源开关设计基础

电源开关的使用较为复杂,甚至让大多数电子产品设计人员都感到困惑,特别是对那些非电源管理专家而言.在各种各样的应用中,例如:便携式电子产品、消费类电子产品、工业或电信系统等,广大设计人员正越来越多地使用电源开关.这些电源开关的使用方式多种多样,包括控制、排序,电路保护、配电甚至是系统电源开启管理等.当然,每一种用法都需要有不同特性的电源开关解决方案.