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991.
We present a new PLL based frequency synthesizer, in which we have replaced the conventional phase frequency detector and the dividers (programmable counters) with a sequential dual input phase accumulator (DIPA), consisting of a digital circuit employing adders, registers and a ladder. The main feature of the DIPA is that the two input frequencies are not required to be normalized (divided down) to the step frequency of the synthesizer. Instead, the two different high frequencies, that is the reference and the output frequency of the synthesizer, are applied directly. The DIPA samples and normalizes their phases at very high rates, calculates their phase difference, producing an output that consists of a dc component proportional to the phase difference and harmonics of the two input high frequencies. These harmonics are high frequencies and can easily be rejected by a wide bandwidth filter of the loop, without affecting the high convergence speed of the loop. Moreover, these harmonics do not generate spurs near the output frequency. The resolution of the DIPA based synthesizer depends only on the length of the digital word of the DIPA, and its convergence speed depends on the lower of the two input frequencies. The output of the DIPA is a linear function of the phase difference of the two input frequencies and its dynamic range exceeds the limit of ±2π that governs the conventional phase detectors. Thus, the proposed frequency synthesizer based on the DIPA has low phase noise, no spurs nearby the output frequency, high resolution and fast convergence rate. Additionally, the output frequency can be digitally modulated under the control of the closed loop, either by phase or frequency modulation. 相似文献
992.
LED背光源现况与展望 总被引:1,自引:0,他引:1
现阶段,LED被广泛地应用到中小尺寸背光源中,大尺寸TV背光源也由原来的CCFL向LED转变。LED背光源的优势有低能耗、无汞环保、超薄化结构设计、高色彩饱和度、高品质画面显示,其应用领域广阔,几乎涵盖了中小尺寸、大尺寸显示应用领域。文章介绍了国内外LED背光源的标准体系建立情况,并根据当前产业面临的困难提出大尺寸LED背光源的发展方向。 相似文献
993.
本文介绍了新一代IHM.B具备更强机械性能的高功率IGBT模块,其融合了最新的设计、材料、焊接和安装技术。首批IHMB模块将搭载最新的、采用沟槽栅单元设计的3.3kV IGBT3芯片,在保持机械兼容性的同时,极大地提高了器件的热效率和电气效率。本文还对宇宙射线以及功率循环试验进行了研究。 相似文献
994.
995.
Let λ(n) be the n-th normalized Fourier coeficient of a holomorphic Hecke eigenform f(z) ∈ Sk(Γ) for the full modular group.In one of his papers,Sankaranarayanan mentioned that it is an open problem to give a non-trivial estimate for the sum of λ(n) over cubes,i.e.n x λ(n3).In this paper,we are able to use the analytic properties of symmetric power L-functions to solve his problem.More precisely,we prove that Σn≤zλ(n3) x(3/4 +ε),Σn≤zλ(n4) x(97+ε). 相似文献
996.
unit-gain compensation ceil and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor.Their advantages and limitations are discussed and verified by simulation results. 相似文献
997.
Takenobu Kajikawa 《Journal of Electronic Materials》2009,38(7):1083-1088
The results of research and development in the Japanese national project “Development for Advanced Thermoelectric Conversion
Systems” are summarized, and the approaches to practical use of advanced thermoelectric modules and power generation systems
are presented. The 5-year national project was successfully completed in March 2007. Three kinds of high- efficiency cascaded
thermoelectric modules and two kinds of innovative Bi-Te thermoelectric modules were successfully developed. Heat cycle tests
for three types of modules were also completed. Moreover, four types of advanced thermoelectric power generation systems were
experimentally demonstrated for recovery of waste heat from the industrial and private sectors. In order to proceed further,
thermoelectric power generation systems using practical heat sources were followed after installation of the developed modules.
In parallel, various approaches for practical use by private companies, as well as plans for the next-phase project by the
National Institute of Advanced Industrial Science and Technology (AIST) and the Engineering Advancement Association (ENAA),
were also followed. The scenarios to proceed to the commercial phase of thermoelectric power generation are discussed on the
basis of the results of the national project. 相似文献
998.
Sharona Sedghani Cohen Vardit Eckhouse Asher A. Friesem Nir Davidson 《Optics Communications》2009,282(9):1861-1866
We show that by coherently combining several solid state lasers it is possible to obtain a single frequency output. This is experimentally demonstrated by coherently combining four Nd:YAG lasers channels, each with a properly chosen cavity length, in order to suppress unwanted longitudinal modes and obtain a single frequency output. We also present a model that accurately predicts and supports out experimental results. 相似文献
999.
现代电视设备技术不断更新,这对供电电源的质量提出更高的要求,不仅要求稳定的工作电压,还要尽量减少各种杂波的干扰,这就牵涉到广播电视配电系统的接地问题,就此问题进行分析。 相似文献
1000.
At present, the major drawback for mobile phones is the issue of power consumption. As one of the alternatives to decrease the power consumption of standard, power-hungry location-based services usually require the knowledge of how individual phone features consume power. A typical phone feature is that the applications related to multimedia streaming utilize more power while receiving, processing, and displaying the multimedia contents, thus contributing to the increased power consumption. There is a growing concern that current battery modules have limited capability in fulfilling the long-term energy need for the progress on the mobile phone because of increasing power consumption during multimedia streaming processes. Considering this, in this paper, we provide an offline meaning sleep-mode method to compute the minimum power consumption comparing with the power-on solution to save power by implementing energy rate adaptation (RA) mechanism based on mobile excess energy level purpose to save battery power use. Our simulation results show that our RA method preserves efficient power while achieving better throughput compared with the mechanism without rate adaptation (WRA). 相似文献