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“我有一个梦想:某一天三大运营商员工不摆摊了,不打架了,员工年收入差距缩小了,前端营业员待遇提高了,后端装维与资源矛盾化解了,服务质量提高了,恶性竞争消除了,重复建设停止了,不再破坏对手广告了,不互挖墙角搞策反了,不再零元购机了,不打价格战了,都能活的有尊严了”. 相似文献
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本文提出了一种无需检测电感电流及其过零点的简单数字控制方案,实现了临界连续模式功率因数校正器的控制。取得了功率开关管的ZVZCS,消除了整流二极管和快恢复二极管的反向恢复带来的损耗,提高了变换器的效率和可靠性;另外,数字控制器克服了模拟IC控制器的开关频率限制问题,消除了输入电流的低频畸变,提高了功率因数;同时,也降低了输入电感的值,降低了成本的同时提高了功率密度。为实现中小功率数字控制功率因数校正器的产品化提供了一个良好的解决方案。 相似文献
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徐翠翠 《电子技术与软件工程》2021,(3):232-234
本文研究了供水系统运行状态实时模拟模型,首先对数据进行了预处理,然后运用多元线性回归,给出了准则判断了数据优势;建立了供水系统与用水量之间的数学模型,并给出了误差分析,探讨了供水量和用水量对模型的影响。 相似文献
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分析了小波压缩的相关理论知识,着重对JPEG2000系统中的ROI功能进行了研究,实现了ROI的构思和实用算法,给出了性能分析,进而分析了目前ROI算法的局限性并给出了ROI的改进算法,做出了相应的实验结果分析. 相似文献
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铝电解电容器技术的新进展 总被引:3,自引:3,他引:0
详细讨论了电子技术的发展对铝电解电容器的性能要求,提出了其技术对策,分析了存在的技术瓶颈,找出了它的技术出路,探讨了它的技术难点,给出了当前我国铝电解电容器行业的技术现状,指出了未来发展方向。 相似文献
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在当今的社会中,人们已经离不开电子通信了,其作为了一个新兴产业,并得到了良好的应用,对各行各业起到了促进作用,同时,传统的产业收到了冲击。我国的电子通信发展较快,达到了先进的水平,不过,由于发展时间较短,存在很多不足之处,拉低了整体水平。特别是干扰问题,严重影响了电子通信的发展。本文对电子通信进行了概述,探讨了干扰要素,并且,提出了相关的应对策略。 相似文献
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Optical and electrical characteristics of GaN vertical light emitting diode with current block layer
A GaN vertical light emitting diode(LED)with a current block layer(CBL)was investigated.Vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL were fabricated.Optical and electrical tests were carried out.The results show that the light output power of vertical LEDs with a non-ohmic contact CBL and with a silicon dioxide CBL are 40.6%and 60.7%higher than that of vertical LEDs without a CBL at 350 mA,respectively.The efficiencies of vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL drop to 72%,78%and 85.5%of their maximum efficiency at 350 mA,respectively. Moreover,vertical LEDs with a non-ohmic contact CBL have relatively superior anti-electrostatic ability. 相似文献
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This work proposes a finite element numerical methodology to predict the thermal resistance of both flip chip-plastic ball grid array (FC-PBGA) with a bare die and FC-PBGA with a metal cap. The 3D finite element model was initially constructed to simulate the thermal resistance of FC-PBGA. A thermal resistance experiment was performed to verify the FEM results, following the construction of specimens of FC-PBGA with a bare die and with an aluminum cap, using six-layered substrate. The verified finite element model was employed to determine the thermal resistance of FC-PBGA with a copper cap using four-layered and six-layered substrates. Experimental results demonstrated that FC-PBGA with a metal cap improves thermal performance by 35% over with a bare die. FC-PBGA with a copper cap slightly improves thermal performance from 2% to 2.8% over that of FC-PBGA with an aluminum cap. The thermal resistance of FC-PBGA with a four-layered substrate is reduced by 4.0% to 5.9% from that of FC-PBGA with a six-layered substrate, since the four-layered substrate contains less metal. The finite element numerical results negligibly differ from the experimental results by 6% to 8.1%. A finite element numerical methodology is here proposed to predict the thermal resistance of FC-PBGA. The methodology is effective in researching and developing new products or improving existing packages. 相似文献
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Suzuki H. Watanabe K. Ishikawa K. Masuda H. Ouchi K. Tanoue T. Takeyari R. 《Solid-State Circuits, IEEE Journal of》1998,33(9):1313-1320
High-speed ICs for 20-40-Gbit/s time-division multiplexing (TDM) optical transmission systems have been designed and fabricated by using InP/InGaAs heterojunction-bipolar-transistor (HBT) technology. This paper describes four analog ICs and four digital ICs: a five-section cascode distributed amplifier with a gain of 9.5 dB and a bandwidth of 50 GHz, a three-section single-end-to-differential converter with a bandwidth of 40 GHz, a cascode differential amplifier with a gain of 10.5 dB and a bandwidth of 64 GHz, a preamplifier with a gain of 41.9 dBΩ and a bandwidth of 39 GHz, a modulator driver with an output voltage swing of 3.2 V peak-to-peak and rise and fall times of 16 and 15 ps, a 40-Gbit/s selector, a 20-Gbit/s D-type flip-flop, and a static frequency divider with an operating range of 2.0-44.0 GHz. All the ICs were measured with on-wafer RF probes 相似文献
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A Gunn device has been integrated with two types of active planar notch antennas. The first types uses a coplanar waveguide (CPW) resonator an a stepped-notched antenna with bias tuning to achieve a bandwidth of 275 MHz centered at 9.33 GHz with a power output of 14.2±1.5 dBm. The second type uses a CPW resonator with a varactor for frequency tuning to achieve a bandwidth of over 1.3 GHz centered at 9.6 GHz with a power output of 14.5±0.8 dBm. This is equivalent to over 14% electronic tuning bandwidth. Both configurations exhibit a very clean and stable output signal. A theoretical circuit model was developed to facilitate the design. The model agrees well with experimental results. Injection-locking experiments on the second configuration show a locking gain of 30 dB with a locking bandwidth of 30 MHz at 10.2 GHz. Power combining experiments of two-varactor-tuned CPW active notch antenna elements in a broadside configuration have achieved well over 70% combining efficiency throughout the wide tuning range. The circuits have advantages of small size, low cost, and excellent performance 相似文献
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提出一种基于SDB技术的非平面埋氧层SOI材料制备方法.其关键技术包括:通过干法刻蚀、高压氧化和淀积二氧化硅获得高质量非平面埋氧层;通过化学气相淀积多晶硅来形成键合缓冲层,并运用回刻光刻胶和化学机械抛光来实现键合面的局部和全局平坦化;通过室温真空贴合、中温预键合和高温加固键合来进行有源片和衬底片的牢固键合.基于该技术研制了有源层厚度为21μm、埋氧层厚度为0.943μm、顶面槽和底面槽槽高均为0.9μm的具有双面绝缘槽结构的非平面埋氧层新型SOI材料.测试结果表明该材料具有结合强度高、界面质量好、电学性能优良等优点. 相似文献
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Mahmud A. Kalkur T.S. Jamil A. Cramer N. 《Microwave and Wireless Components Letters, IEEE》2006,16(5):261-263
An active phase shifter circuit implemented with discrete components is reported. The tuning element, a ferroelectric varactor, is a parallel plate capacitor with Ba/sub 0.5/Sr/sub 0.5/TiO/sub 3/ (BST) as the dielectric. The circuit consists of two bipolar junction transistors coupled with a feedback network, which contains the varactor and thus produces a transfer function that can be varied with a control voltage. The active nature of the circuit allows for signal gain, while the BST varactor provides a high-Q tuning element. This represents an improvement over strictly passive phase shifters with ferroelectric elements. Circuit simulation results are presented and compared with measured data from the implemented system. The network, even with markedly nonideal transistors, can provide a true all-pass response over the frequency band of interest (200-1100 MHz). The measurement results demonstrate an analog tunability of about 100/spl deg/ with a gain variation of about 0.6 dB at I GHz when using a BST capacitor with a tunability of 2.75:1. 相似文献
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Tunable multiwavelength fiber ring lasers using a programmable high-birefringence fiber loop mirror 总被引:3,自引:0,他引:3
L.R. Chen 《Photonics Technology Letters, IEEE》2004,16(2):410-412
We demonstrate a comb filter with digitally tunable wavelength spacing using a programmable high-birefringence (HiBi) fiber loop mirror (FLM). We then use the HiBi-FLM to implement a tunable multiwavelength semiconductor optical amplifier (SOA)-based fiber ring laser and a tunable multiwavelength all-fiber Raman ring laser. Both lasers exhibit stable room-temperature operation and have a wavelength spacing that is digitally tunable between 1.6 and 3.2 nm. With the SOA-based configuration, we obtain six wavelengths with a spacing of 3.2 nm and 11 wavelengths with a spacing of 1.6 nm; with the all-fiber Raman-based configuration, we obtain four wavelengths with a spacing of 3.2 nm and five wavelengths with a spacing of 1.6 nm. 相似文献
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Kyu Hwan An Ockgoo Lee Hyungwook Kim Dong Ho Lee Jeonghu Han Ki Seok Yang Younsuk Kim Jae Joon Chang Wangmyong Woo Chang-Ho Lee Haksun Kim Laskar J. 《Solid-State Circuits, IEEE Journal of》2008,43(5):1064-1075
Fully integrated CMOS power amplifiers (PAs) with parallel power-combining transformer are presented. For the high power CMOS PA design, two types of transformers, series-combining and parallel-combining, are fully analyzed and compared in detail to show the parasitic resistance and the turn ratio as the limiting factor of power combining. Based on the analysis, two kinds of parallel-combining transformers, a two-primary with a 1:2 turn ratio and a three-primary with a 1:2 turn ratio, are incorporated into the design of fully-integrated CMOS PAs in a standard 0.18-mum CMOS process. The PA with a two-primary transformer delivers 31.2 dBm of output power with 41% of power-added efficiency (PAE), and the PA with a three-primary transformer achieves 32 dBm of output power with 30% of PAE at 1.8 GHz with a 3.3-V power supply. 相似文献
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In this paper, we develop and analyze a simple algorithm for scheduling variable length messages in WDM networks with a passive star coupler. We base our schemes on a star topology with centralized control and use a scheduling algorithm similar to the process management in UNIX system. Every node and message have a scheduling priority associated with them. By comparing our algorithm with random select algorithm, we find that significant improvement in performance can be achieved with very little extra cost. 相似文献