共查询到20条相似文献,搜索用时 78 毫秒
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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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针对采用芯片nRF905的LED屏无线通信,分别给出了上位机和下位机的系统框图,分析了系统的功耗,比较了无线模块和串口通信的通信速率,验证了系统的可行性,设计了串口通信协议,为保证数据质量,设计了数据通信协议,针对串口数据的nRF905分包转发,设计了无线芯片通信协议,例举了状态机的5种状态,介绍了状态间的转换条件,巧妙地编程设计了通信数据的定时器检查,论述了基于状态机的嵌入式单片机软件编程。 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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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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The formation and characteristics of a parasitic conduction band barrier located at a SiGe/Si heterojunction have been investigated using a commercial numerical simulator and a simple, three-region model of a heterojunction with a nearby p–n junction. The barrier’s formation is examined as a function of the displacement of the p–n junction from the heterojunction, but also found to depend on the germanium concentration, junction doping and the applied bias. The phenomenon is of interest for understanding the performance of SiGe/Si heterojunction bipolar transistors, where the p–n junction is intentionally displaced from the heterojunction at either the emitter or collector junctions or where boron outdiffusion from the base produces p–n junction displacement. The barrier is found to scale with the germanium mole fraction and to be significantly larger when the heterojunction is displaced into the p-side of the p–n junction. Beyond some minimum separation of the junctions, the barrier height rises with junction displacement and saturates. For a given displacement, the barrier’s height can be suppressed with reverse bias or enhanced by forward bias of the p–n junction. The results of the numerical simulations are compared with those from a simple analytical model as an aid in understanding the barrier’s formation and characteristics. 相似文献
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Y. M. Hsin H. T. Hsu K. P. Hseuh W. B. Tang C. C. Fan C. H. Wang C. W. Chen N. Y. Li 《Journal of Electronic Materials》2003,32(9):948-951
The effects of rapid thermal annealing (RTA) on InGaP/InGaAsN heterojunction bipolar transistors (HBTs) with a carbon-doped
base have been studied. The hydrogen and nitrogen concentrations in the base, as well as the direct current (DC) and radio
frequency (RF) device performance, were studied as a function of the annealing temperature. A 30-sec anneal at 650°C and 700°C
under N2 ambient effectively eliminates hydrogen from the base. As the annealing temperature is increased, the base sheet resistance
decreases, and the corresponding maximum frequency of oscillation increases. For all annealing temperatures studied, we found
degradation in the DC gain, presumably caused by the increase of nitrogen concentration in the base region. 相似文献
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Jin Dongyue Zhang Wanrong Shen Pei Xie Hongyun Wang Yang Zhang Wei He Lijian Sha Yongping Li Jia Gan Junning 《Solid-state electronics》2008,52(6):937-940
Multi-finger power SiGe heterojunction bipolar transistors (HBTs) with emitter ballasting resistor and non-uniform finger spacing are fabricated, and temperature profiles of them are measured. Experimental results show that both of them could improve the temperature profile compared with an HBT which has uniform finger spacing. For the HBT with emitter ballasting resistor, the ability to lower the peak temperature is weakened as power increases. However, for the HBT with non-uniform finger spacing, the ability to improve temperature profile is kept over a wide biasing range. Therefore, the experimental results directly prove that the technique of non-uniform finger spacing is a better method for enhancing the thermal stability of power HBTs over a wide biasing range. 相似文献
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The pentode valve is a well-known vacuum tube device which has wide applications. In some of the applications the suppressor grid of a pentode, instead of being connected to the cathode, is given a negative bias. Under these conditions the transconductance of the pentode becomes a function of both suppressor and control grid voltages. A general equation For this transconductance is obtained which is useful for analysis of circuits employing this configuration. 相似文献
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A SiC light-activated Darlington heterojunction transistor is proposed for anti-EMI (electromagnetic interference) applications, in which a monolithically integrated SiCGe/SiC pn heterojunction photodiode is employed to produce a light-induced base current for triggering the transistor. Performance of the proposed light-activated power switch was simulated using MEDICI tools. Feasibility of the proposal is confirmed by its good light-activation characteristics obtained from the simulation. The simulation also demonstrates that good I-V characteristics with a light-independent turn-on voltage knee of about 5 V may be achievable to the light-activated power switch has. 相似文献
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Modeling of SiGe-base heterojunction bipolar transistor with gaussian doping distribution 总被引:2,自引:0,他引:2
The results of numerical modeling of the base transit time and collector current of SiGe-base heterojunction bipolar transistors with a Gaussian base doping profile and two Ge profiles (linearly graded and box) are presented for the first time. The importance of including the dependence of minority carrier mobility on the drift field and the dependence of the effective density of states on the Ge concentration along the base is demonstrated through the analysis of base transit time and collector current. A function describing the decrease of the density of states product in strained SiGe layers with increasing Ge concentration is proposed. 相似文献