共查询到20条相似文献,搜索用时 46 毫秒
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Jian Sun 《Power Electronics, IEEE Transactions on》2005,20(2):308-314
The input impedance of single-phase boost power factor corrected (PFC) AC-DC converters is modeled and analyzed in this paper. A large-signal model is presented for the input impedance which overcomes the limitations of traditional piece-wise linearized models. The model is valid at frequencies ranging from the crossover frequency of the output voltage loop to half the switching frequency of the converter. Experimental results from a boost single-phase PFC converter are provided to validate the model. Input characteristics of typical boost PFC converters, such as input impedance dipping, leading phase of the input current, and responses to distorted input voltages are studied by using the model. A simple compensation technique to reduce the dipping in the input impedance, thereby improving converter performance and minimizing the potential for undesirable interactions with the input filter or the ac source, is also presented. 相似文献
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This paper presents a low-cost test technique using a new RF Built-In Self-Test (BIST) circuit for 4.5-5.5 GHz low noise amplifiers (LNAs). The test technique measures input impedance, voltage gain, noise figure, input return loss and output signal-to-noise ratio of the LNA. The BIST circuit is designed using 0.18 μm SiGe technology. The BIST circuit contains test amplifier and RF peak detectors. The complete measurement set-up contains LNA with BIST circuit, external RF source, RF relays, 50 Ω load impedance, and a DC voltmeter. The test technique utilizes output DC voltage measurements and these measured values are translated to the LNA specifications such as input impedance and gain through the developed equations. The technique is simple and inexpensive. 相似文献
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提出了利用微带天线的宽带输入阻抗模型进行有源集成天线的设计方法以预测有源集成天线(AIA)的辐射特性和谐波特性.谐波平衡法被用于得到AIA的谐波特性和阻抗模型的端口电压.然后端口电压作为激励源计算天线特性.实验结果显示该方法可以简单有效进行有源集成天线设计. 相似文献
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Weidenbrug R. Dawson F.P. Bonert R. 《Industrial Electronics, IEEE Transactions on》1993,40(5):505-511
An improved approach to obtaining good zero-voltage-crossing signals is presented. These signals are subsequently used as synchronization signals for a phase-controlled thyristor power converter. Detection of accurate zero crossings is possible even when there are large frequency changes, sudden load changes, or large commutation overlap angles. The improved accuracy in the integrity of the zero crossing is obtained by reconstructing a voltage representing the AC source voltage. This voltage is determined from the distorted thyristor converter input voltage, the converter input current, and an online identification of the source impedance using a microcontroller-based adaptive algorithm. The improvement provided by the new zero crossing detection scheme is verified experimentally 相似文献
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An amplifier for an active electrode is described which requires only a two-conductor connecting cable, is current limiting for patient safety, and has essentially unity voltage gain. In addition, the output impedance is lower and the input impedance has more adjustment latitude than is possible with a conventional source follower. 相似文献
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A Miller-integrator circuit using a simple amplifier with positive feedback has been analysed. The circuit has the high input impedance inherent with insulated-gate field-effect transistors and the low output impedance characteristic of emitter followers. Owing to these properties and the high voltage gain, it is possible to obtain long-duration sweeps of good linearity. A sweep of about 2 h duration and of a linearity error of 0.05% has been obtained. The ratio of the dynamic range of the output voltage to the supply voltage is greater than 60%, and the output impedance is less than 10?. 相似文献
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Three-step impedance criterion for small-signal stability analysis in two-stage DC distributed power systems 总被引:1,自引:0,他引:1
Small-signal stability analysis methods based on an impedance criterion originate from the minor loop gain method and are gradually utilized in two-stage DC distributed power systems. In this paper, we conclude that the impedance criterion directly dependent on output impedance Z/sub o/(s) of the source subsystem and input impedance Z/sub i/(s) of the load subsystem is possible but gives an incorrect stability analysis for systems with a regulated source subsystem. Through introducing a mapped pure impedance of the load subsystems and the preliminary system, we develop a general three-step impedance criterion, with which a correct small-signal stability analysis can be guaranteed, regardless of the type of source subsystem. Furthermore, we introduce the application of the three-step impedance criterion in two small-signal stability analysis cases and utilize it in an example system to predict the stability shift process arising from the variation on the load resistance and input voltage value. 相似文献
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This paper presents a low‐cost RF parameter estimation technique using a new RF built‐in self‐test (BIST) circuit and efficient DC measurement for 4.5 to 5.5 GHz low noise amplifiers (LNAs). The BIST circuit measures gain, noise figure, input impedance, and input return loss for an LNA. The BIST circuit is designed using 0.18 μm SiGe technology. The test technique utilizes input impedance matching and output DC voltage measurements. The technique is simple and inexpensive. 相似文献
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An analytical investigation was performed to ascertain the explicit effects of the state-variable feedback control-law coefficients and the source variable feed-forward control-law coefficients on the stability and performance in linearized multiloop (pulse-width modulated) switching regulators. Detailed results are presented for input impedance, output current susceptibility, input voltage susceptibility and output impedance of the basic buck, boost, and buck-boost regulators. General relationships are derived for the feed-forward control-law coefficients to minimize input voltage susceptibility and the output impedance of the multiloop buck regulator. Relationships for all three regulators based on other performance measures such as output current susceptibility can be derived using the results presented. Simplified results are given for multiloop switching regulators with a conventionally implemented current loop and with a value of inductance several times greater than critical 相似文献
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This paper presents a variable gain low-noise amplifier (VG-LNA) for 5 GHz applications.The effect of the input parasitic capacitance on the inductively degenerated common source LNA's input impedance is analyzed in detail.A new ESD and LNA co-design method was proposed to achieve good performance.In addition,by using a simple feedback loop at the second stage of the LNA,continuous gain control is realized.The measurement results of the proposed VG-LNA exhibit 25 dB (-3.3 dB to 21.7 dB) variable gain range,2.8 dB noise figure at the maximum gain and 1 dBm IIP3 at the minimum gain,while the DC power consumption is 9.9 mW under a 1.8 V supply voltage. 相似文献
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无源UHF RFID标签的低成本阻抗匹配网络设计 总被引:1,自引:0,他引:1
提出了一种符合ISO/IEC18000-6C标准的无源RFID(射频识别)标签的低成本阻抗匹配网络。该设计基于复功率波反射系数的概念,修正芯片输入阻抗,在片内添加阻抗匹配电路。通过变化芯片阻抗和天线共轭匹配及失配间切换,有效完成信号的调制反射。提出的电路结构简单,易于实现,在读写器、标签天线和芯片之间实现了功率传输的最大化,提高了芯片输入电压以及读写器对标签反射信号的识别率。采用该阻抗匹配网络的芯片基于chartered 0.35μm CMOS工艺实现。测试结果表明,在923MHz频带下,倍压电路输出可达1.47V,标签满足系统设计要求。 相似文献
13.
《Microwave Theory and Techniques》1955,3(1):37-39
A simple relation between optimum rf source impedance for minimum noise figure and the nominal conversion loss of a mixer is derived. This impedance is related to the input mismatch and its dependence on the type of IF amplifier input circuit is discussed. Relations between the crystal noise temperature and mixer noise temperature as a function of conversion loss are derived for different load conditions at the image frequency terminals. 相似文献
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Stability margin monitoring for DC distributed power systems via perturbation approaches 总被引:1,自引:0,他引:1
Jinjun Liu Xiaogang Feng Lee F.C. Borojevich D. 《Power Electronics, IEEE Transactions on》2003,18(6):1254-1261
In multi-module power electronics systems, especially DC distributed power systems, the small-signal stability issues are often dealt with by employing Middlebrook's impedance criterion. However, for on-line system stability margin monitoring, directly measuring impedance of the source and load subsystems then making quantitative comparisons is too complicated and difficult. This paper proposes practical and simple methods, which involve applying current or voltage perturbation to the dc side of distributed power systems then only measuring the amplitude of two currents or voltages in order to monitor the stability margin. For both methods (current perturbation and voltage perturbation), an implementation approach that does not employ external voltage or current perturbation source is also presented. All these methods and approaches are equivalent to the impedance measuring and comparing method based on the impedance criterion with different forbidden regions. A comparative evaluation of each method and its corresponding implementation approach is provided. 相似文献
16.
The use of a junction-f.e.t. matched pair, functioning as a self-biased source follower, bootstrapped by the operational amplifier voltage follower it drives, facilitates the design of an a.c.-coupled oscilloscope probe with maximised input impedance. Consequently, a lower-cutoff frequency of less than 3 Hz is feasible with input coupling components that are not incompatible with current i.c. design practice. 相似文献
17.
提出了一种使用输入阻抗来诊断无刷直流电动机(brushless dc motors,BLDC)定子绕组匝间故障(inter-turn fault,ITF)的算法,并设计了相应的故障检测系统进行了实现。该系统的优势在于具有早期检测能力以及适用于各种速度范围检测。提出的故障检测技术通过使用输入电压和输入电流来计算输入阻抗,并将其与数据库中的数值比较。相比传统的方法,由于不需要快速傅里叶变换(FFT),因此提出的算法更加迅速且简单。实验测试结果表明提出的检测方法在各种转速条件下均具有较高的精确度。 相似文献
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The finite-difference time-domain (FDTD) method is routinely used to calculate the input admittance/impedance of simple antennas. The value of the input admittance/impedance depends on the level of discretization used in the method, and should converge to a final value as the discretization becomes finer. In this paper, the level of discretization necessary for convergence is studied using two common feed models: the hard-source feed and the transmission-line feed. First, the simplest and most naive methods for introducing the voltage and the current in these models are considered, and the results for the admittance are shown not to converge. Next, improved methods for introducing the voltage and current in these models are constructed. The results for the admittance are then shown to converge, and guidelines are offered for the level of discretization needed for convergence. In addition, two general problems associated with the computation of the admittance are discussed: the agreement between admittances computed with different simple feed models, and the agreement between these admittances and measurements. 相似文献