Protecting local access telecommunications networks: Toward a minimum-cost solution

The problem of designing fibre-optic networks for local-access telecommunications generates (at least) three non-trivial subproblems. In the first of these subproblems one must determine how many fibre-optic cables (fibres) are required at either end of a street. In the next subproblem a minimum-cost network must be designed to support the fibres. The network must also provide distinct paths from either end of the street to the central exchange(s). Finally, the fibre-optic cables must be placed in protective covers. These covers are available in a number of different sizes, allowing some flexibility when covering each section of the network. In this paper we describe a dynamic programming (DP) formulation for finding a minimum-cost (protective) covering for the network (the third of the subproblems). This problem is a generalised set covering problem with side constraints and is further complicated by the introduction of fixed and variable welding costs. The DP formulation selects covers along each arc (in the network), but cannot exactly model the fixed costs and so does not guarantee optimality. We also describe an integer programming (IP) formulation for assessing the quality of the DP solutions. The cost of the networks constructed by the IP model is less than those designed using the DP model, but the saving is not significant for the problems examined (less than 0.1%). This indicates that the DP model will generally give very good solutions. Furthermore, as the problem dimensions grow, DP gives significantly better solution times than IP.     

Improving the electrical and mechanical behavior of electrically conductive paint by partial replacement of silver by carbon black

Partial replacement of silver particles by carbon black (low cost) in electrically conductive paint was found to decrease the electrical resistivity and increase the scratch resistance of the resulting thick film, which is for use in electrical interconnections. An effective carbon black content is 0.055 of the total filler volume. By using a total solid volume fraction of 0.1969 and a silane-propanol (1:1 by weight) solution as the vehicle, a paint that gives a thick film with resistivity 2 × 10⁻³ Ω·cm has been attained.     

Wide dynamic range parallel feedback transimpedance amplifier for 10 Gb/s optical links

This paper presents the design and implementation of a new wide dynamic range parallel feedback (PF) transimpedance amplifier (TIA) for 10 Gb/s optical links. The wide dynamic range is attributed to the novel TIA architecture employing both shunt-shunt and shunt-series feedback networks. The outstanding features of the TIA are wide dynamic range, high gain, low power consumption and design simplicity. A prototype implemented in a 0.5 μm SiGe BiCMOS technology and operating at −3.3 V power supply features an 18.4 dBm dynamic range with a BER less than 10⁻¹², an optical sensitivity of −16 dBm, optical overload of +2.4 dBm, a bandwidth of 8.27 GHz, a gain of 950 Ω and a power consumption of 189 mW. The new parallel feedback architecture offers improved overload and noise performance when compared to previously reported, state of the art, single feedback TIA designs and meets all the 10 Gigabit Ethernet and short-reach OC-192 SONET specifications. Ricardo Andres Aroca received the B.S. (Hons) degree in electrical engineering from the University of Windsor, Canada, and the M.S. degree from the University of Toronto, Canada, in 2001 and 2004, respectively. In 2000 he spent two 4 month internships with Nortel Networks in the Microelectronics Department. Mr. Aroca received the Natural Sciences and Engineering Research Counsel of Canada (NSERC) Postgraduate Scholarship award in 2002. He is currently working toward the Ph.D. degree at the University of Toronto where his research interests lie in the area of high-frequency integrated circuits for wireless and wireline communication systems. C. Andre T. Salama received the B.A.Sc. (Hons.) M.A.Sc. and Ph. D. degrees, all in Electrical Engineering, from the University of British Columbia in 1961, 1962 and 1966 respectively. From 1962 to 1963 he served as a Research Assistant at the University of California, Berkeley. From 1966 to 1967 he was employed at Bell Northern Research, Ottawa, as a Member of Scientific Staff working in the area of integrated circuit design. Since 1967 he has been on the staff of the Department of Electrical and Computer Engineering, University of Toronto where he held the J.M. Ham Chair in Microelectronics from 1987 to 1997. In 1992, he was appointed to his present position of University Professor for scholarly achievements and preeminence in the field of microelectronics. In 1989-90, he was awarded the ITAC/NSERC Research Fellowship in information technology. In 1994, he was awarded the Canada Council I.W. Killam Memorial Prize in Engineering for outstanding career contributions to the field of microelectronics. In 2000, he received the IEEE Millenium Medal. In 2003, he received the Outstanding Lifetime Achievement Award from the Canadian Semiconductor Technology Conference for seminal and outstanding contributions to semiconductor device research and promotion of Canadian University research in microelectronics. In 2004, he received the NSERC Lifetime Achievement Award of Research Excellence for outstanding and sustained contributions to the field of microelectronics and the Networks of Centres of Excellence (NCE) Recognition Award for research excellence and outstanding leadership.He was associate editor of the IEEE Transactions on Circuits and Systems in 1986–88 and a member of the International Electron Devices Meeting (IEDM) Technical Program Committeein 1980–82, 1987–89 and 1996–98. He was the chair of the Solid State Devices Subcommittee for IEDM in 1998 and was a member of the editorial board of Solid State Electronics from 1984 to 2002. He is presently a member of the editorial board of the Analog IC and Signal Processing Journal and the Technical Program Committee of the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the Technical ProgramCommittee of the International Symposium on Low Power Electronics and Design (ISLPED). He chaired the technical program committee of ISPSD in 1996 and was the general chair for the conference in 1999.Dr. Salama is the Scientific Director of Micronet, a network of centres of excellence focussing on microelectronics research and funded by the Canadian Government and Industry. He has published extensively in technical journals, is the holder of eleven patents and has served as a consultant to the semiconductor industry in Canada and the U.S. His research interests include the design and fabrication of semiconductor devices and integrated circuits with emphasis on deep submicron devices as well as circuits and systems for high speed, low power signal processing applications. Dr. Salama is a Fellow of the Institute of Electrical and Electronics Engineers, a Fellow of the Royal Society of Canada, a Fellow of the Canadian Academy of Engineering, a member of the Association of Professional Engineers of Ontario, the Electrochemical Society and the Innovation Management Association of Canada.     

Dynamic voltage scaling for series hybrid amplifiers

We present an optimization of the voltage scaling algorithm in low power audio class-G amplifier for headphones application to allow longer playback time. The optimization approach minimizes the voltage difference between the internal audio amplifier power supply and its output signal over a large range of operating conditions. The modeling is based on a behavioral model enabling accurate and rapid evaluation of efficiency and audio quality with realistic input stimuli. The model validated in practice is used to optimize the voltage scaling using only few power supply levels. Thanks to a global search algorithm followed by a local one, the optimization gives the better parameters for voltage scaling algorithm while keeping a good audio quality. The proposed configuration increases the efficiency up to 48% at nominal operation.     

一种抗总剂量辐照的新型PD SOI器件

提出了一种具有叠层埋氧层的新栅型绝缘体上硅(SOI)器件.针对SOI器件的抗总电离剂量(TID)加固方案,对绝缘埋氧层(BOX)采用了叠层埋氧方案,对浅沟槽隔离(STI)层采用了特殊S栅方案.利用Sentaurus TCAD软件,采用Insulator Fixed Charge模型设置固定电荷密度,基于0.18 μm ...     

接触电极功函数对反式锡基钙钛矿太阳能电池性能的影响

因反式锡基钙钛矿太阳能电池可避免J-V迟滞以及铅元素,基于SCAPS-1D设计结构为ITO/HTL/CH3NH3SnI3/PCBM/back-contact的反式锡基钙钛矿太阳能电池器件.其中NiO、Cu2O以及P3HT分别作为空穴传输层,探讨导电玻璃ITO功函数在4.6?5.0 eV范围内电池性能的变化,并分析Al、...     

基于YIG单晶薄膜的陷波器设计

针对基于环球耦合谐振的钇铁石榴石(YIG)小球陷波器装配调试工艺复杂、不利于多通道集成的问题,提出了一种采用静磁波技术来实现YIG单晶薄膜陷波器结构与设计方法.该文通过对单晶薄膜陷波器工作原理的分析,静磁反向体波的角频率与波数(ω-k)色散特性与微带激励谐振换能器的静磁波激励特性的数值计算及器件仿真优化,设计了调谐工作...     

Low-thermal-budget Au-free ohmic contact to an ultrathin barrier AlGaN/GaN heterostructure utilizing a micro-patterned ohmic recess

A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB) AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56 Ω.mm at an alloy temperat-ure of 550 ℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the spe-cific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emis-sion (TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52 × 1018 cm-3,which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic trans-fer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compat-ible metal-insulator-semiconductor high-mobility transistor (MIS-HEMT) was fabricated with the proposed Au-free ohmic con-tact technique.     

新型电接触材料Ag/La_(1–x)Sr_xCoO_3

回顾了电接触材料的发展历史并介绍了新型电接触材料Ag/La1–xSrxCoO3。分析了Ag/La1–xSrxCoO3电接触材料的性能特点,并指出当前研究中需要解决的关键问题:陶瓷成分及微观结构和复合材料成型工艺对材料最终性能的影响。最后阐述Ag/La1–xSrxCoO3材料可作为电接触材料的一个崭新发展方向。