共查询到20条相似文献,搜索用时 31 毫秒
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介绍了POSCAP钽电容器的特点和优点,其电容量大、等效串联电阻(ESR)低及允许纹波电流大,最适用于高效率、低电压、大电流降压式DC/DC转换器中作输出电容器。详述了POSCAP钽电容器在由LM2745组成的同步整流降压式DC/DC转换器中的应用实例,介绍应用电路如果使用条件发生改变时,经过简单计算确定有关元器件参数(L,C)的方法。 相似文献
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新一代信息技术的发展不仅要求有机固体电解质片式钽电容器的等效串联电阻(ESR)小,更需要在严酷环境中使用时电容量、ESR和漏电流保持稳定。影响钽电容器稳定性的影响因素很多,其中界面稳定性是关键因素之一。为此,在此类电容器生产中引入一种新的界面预处理方法,即在介质氧化膜表面涂敷硅烷偶联剂预涂层,抑制介质氧化膜-聚合物界面的劣化。经过高低温、浪涌电压和125℃-2000 h寿命测试,静电容量、漏电流和ESR的稳定性有明显改善。试验结果表明,该界面预处理技术是制造高稳定性高压有机钽电容器非常有效的方法。 相似文献
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A purely passive parasitic-compensated switched-capacitor circuit is shown to implement a simple signal conversion algorithm consisting of a mere charge division between equal valued capacitors. Such a circuit is the core of the new digital-to-analogue convertor described, and which is particularly suitable for high-frequency applications. Appropriate design conditions are established to render the overall circuit insensitive to the offset voltage and finite DC gain errors of the amplifier 相似文献
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为解决对无人机、平流层飞艇等空中移动目标无线输能时机载接收端整流天线质量大,占居飞行器有效载荷多的难题,设计了一种具有谐波抑制功能的共面波导轻薄圆极化整流天线。该整流天线采用集中式整流方式,通过将整流电路直接集成在微带天线接地板上,实现了质量轻,尺寸小,剖面低,易共形的圆极化整流天线。该天线工作在5.8 GHz,采用共面波导耦合馈电,并在馈线上直接加载共面波导谐振结构进行谐波抑制,具有较宽的工作带宽。整流电路采用倍压整流形式,利用贴片电容作为直通滤波器进行直流滤波,电路结构简单。该整流天线结构紧凑,质量仅6.28 g,剖面厚度0.5 mm,最佳整流效率63.84%,测试结果与仿真结果吻合良好,验证了该设计的可行性。 相似文献
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Axelrod B. Berkovich Y. Ioinovici A. 《IEEE transactions on circuits and systems. I, Regular papers》2008,55(2):687-696
A few simple switching structures, formed by either two capacitors and two-three diodes (C-switching), or two inductors and two-three diodes (L-switching) are proposed. These structures can be of two types: ldquostep-downrdquo and ldquostep-up.rdquo These blocks are inserted in classical converters: buck, boost, buck-boost, Cuk, Zeta, Sepic. The ldquostep-downrdquo C- or L-switching structures can be combined with the buck, buck-boost, Cuk, Zeta, Sepic converters in order to get a step-down function. When the active switch of the converter is on, the inductors in the L-switching blocks are charged in series or the capacitors in the C-switching blocks are discharged in parallel. When the active switch is off, the inductors in the L-switching blocks are discharged in parallel or the capacitors in the C-switching blocks are charged in series. The ldquostep-uprdquo C- or L-switching structures are combined with the boost, buck-boost, Cuk, Zeta, Sepic converters, to get a step-up function. The steady-state analysis of the new hybrid converters allows for determing their DC line-to-output voltage ratio. The gain formula shows that the hybrid converters are able to reduce/increase the line voltage more times than the original, classical converters. The proposed hybrid converters contain the same number of elements as the quadratic converters. Their performances (DC gain, voltage and current stresses on the active switch and diodes, currents through the inductors) are compared to those of the available quadratic converters. The superiority of the new, hybrid converters is mainly based on less energy in the magnetic field, leading to saving in the size and cost of the inductors, and less current stresses in the switching elements, leading to smaller conduction losses. Experimental results confirm the theoretical analysis. 相似文献
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Bor-Ren Lin 《International Journal of Electronics》2018,105(4):679-693
This paper presents a zero-voltage switching DC/DC converter for DC micro-grid system applications. The proposed circuit includes three half-bridge circuit cells connected in primary-series and secondary-parallel in order to lessen the voltage rating of power switches and current rating of rectifier diodes. Thus, low voltage stress of power MOSFETs can be adopted for high-voltage input applications with high switching frequency operation. In order to achieve low switching losses and high circuit efficiency, asymmetric pulse-width modulation is used to turn on power switches at zero voltage. Flying capacitors are used between each circuit cell to automatically balance input split voltages. Therefore, the voltage stress of each power switch is limited at Vin/3. Finally, a prototype is constructed and experiments are provided to demonstrate the circuit performance. 相似文献
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A design of current-mode continuous-time filters for low voltage and high frequency applications using complementary bipolar current mirror pairs is presented. The proposed current-mode filters consist of simple bipolar current mirrors and capacitors and are quite suitable for monolithic integration. Since the filters are based on the integrator type of realization, the proposed method can be used for a wide range of applications. The frequency of the filters can easily be changed by the DC controlling current. A fifth-order Butterworth and a third-order leapfrog filter with tunable cutoff frequencies from 20 MHz to 100 MHz are designed as examples and simulated by SPICE using standard bipolar parameters. 相似文献
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提出一种用于提取神经电信号的新型单片集成CMOS前置放大器.在放大器输入端引入的交流耦合电容可以消除存在于电极-电解液之间的电极极化电压,栅源电压为负值的二极管连接的nMOS晶体管能够作为大电阻,并且占用很小芯片面积,可以通过此大电阻为前置放大器提供直流偏置,同时不影响输入阻抗值.通过对输入级进行理论噪声分析,确定了放大器中的各个器件参数.仿真结果表明,由于采用电容负反馈结构,此放大器的交流增益为38.8dB,无直流增益,在0.1Hz~1kHz频率范围内,总输入等效噪声为277nVrms. 相似文献
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提出一种用于提取神经电信号的新型单片集成CMOS前置放大器.在放大器输入端引入的交流耦合电容可以消除存在于电极-电解液之间的电极极化电压,栅源电压为负值的二极管连接的nMOS晶体管能够作为大电阻,并且占用很小芯片面积,可以通过此大电阻为前置放大器提供直流偏置,同时不影响输入阻抗值.通过对输入级进行理论噪声分析,确定了放大器中的各个器件参数.仿真结果表明,由于采用电容负反馈结构,此放大器的交流增益为38.8dB,无直流增益,在0.1Hz~1kHz频率范围内,总输入等效噪声为277nVrms. 相似文献
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Class E zero-voltage-ripple (ZVR) rectifiers are introduced. The proposed circuits offer a new means of a significant improvement in suppressing the output voltage ripple compared with their predecessors. Therefore, the size of the output filter can be considerably reduced, the rI rms2 conduction power loss in the equivalent series resistance of the filter capacitor can be lowered, aluminum or tantalum electrolytic capacitors may be entirely eliminated, filter capacitors with low capacitances and thereby high self-resonant frequencies can be used, and a faster dynamic response becomes achievable. ZVR is accomplished by reducing the AC component of the current at the input of the output filter. Class E2 and Class D-E ZVR resonant DC/DC power converters are derived using the Class E ZVR rectifiers. An experimental prototype of a Class E2 30 W/500 kHz DC/DC converter was built and tested. Its output voltage ripple was as much as 20 times lower than that of the corresponding conventional converter. The new converters are suitable for noise-sensitive high-output-current applications 相似文献
16.
Lee C.K. Ron Hui S.Y. Henry Shu-Hung Chung 《Industrial Electronics, IEEE Transactions on》2002,49(3):613-617
Power inverter modules fed with separate DC voltage sources of voltage ratio 1:2:4:8 are connected to form a cascade multilevel inverter. This new proposal combines the advantages of the static phase-shifter and chain-cell converter concept. Using the same number of power devices as a standard nine-level inverter, the proposed converter operates as a high-power digital-to-analog converter with 31-level resolution. Electrolytic capacitors used in the proposed inverter for providing the DC voltage sources will never be connected in opposite polarity in all cases, thus ensuring high reliability. The proposal has the potential for uninterruptible power supply and flexible AC transmission applications 相似文献
17.
The lifetimes of metal–insulator–metal (MIM) capacitors are predicted from voltage step stress data. Capacitor areas of 400, 5625 and 11,250 μm2 are investigated. The reliability of capacitors subjected to a single or triple DC pulse prior to a breakdown voltage ramp test is predicted at use conditions (5 V). The method of maximum likelihood is employed in this analysis. With this approach, it is found that the effect of capacitor area on the linear field acceleration parameter, γ, is not statistically significant. Also, it is demonstrated that either a single or a triple DC pulse seriously reduces both the MTTF and γ. Further, the triple DC pulse can change the failure distribution from lognormal to Weibull. The data are also fitted to the reciprocal field model and the predicted failure times under use conditions are too large to be physically reasonable, favoring the linear field model. A graphical method is suggested for discerning between the lognormal and Weibull distributions.This study makes extensive use of statistical methods. One of our goals in this paper is to make the reliability community aware of these powerful techniques so that they may become more widespread. 相似文献
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Tombak A. Maria J.-P. Ayguavives F. Zhang Jin Stauf G.T. Kingon A.I. Mortazawi A. 《Microwave and Wireless Components Letters, IEEE》2002,12(1):3-5
The measurement results for thin film barium strontium titanate (BST) based voltage tunable capacitors intended for RF applications are reported. At 9 V DC, BST capacitors fabricated using MOCVD (metalorganic chemical vapor deposition) method achieved 71% (3.4:1) tunability. The measured device quality factor (Q) for BST varactors is comparable with the device Q for commercially available varactor diodes of similar capacitance. The typical dielectric loss tangent was in the range 0.003-0.009 at VHF. Large signal measurement and modeling results for BST thin film capacitors are also presented 相似文献
20.
This paper develops a new series resonant (current resonant) DC link inverter with a voltage clamped circuit. The proposed circuit has a fixed pulse frequency operation. The fixed pulse frequency at 20-50 kHz enables the system to work without audible noise, and to involve the much smaller-sized DC inductance and output capacitors compared with hard-switched current source inverters. The proposed circuit has a voltage clamped circuit which could control the voltage stress of the switches. In this paper, explanations of the new circuit configuration, the simulation, design considerations, and some experimental results are included 相似文献