全光纤光学电流互感器研究进展

介绍了电子电流互感器的分类与全光纤型电流互感器的基本工作原理,回顾了近年来提出的对全光纤光学电流互感器中的线性双折射、韦尔代常数变化等问题的解决方案,以及有关磁致伸缩、光纤光栅等类型的光学电流传感器的研究进展。     

Meander-Line and Hybrid Meander-Line Transformers

The application of meander lines to impedance transformers is described. Meander-line transformers have less bandwidth than stepped-impedance transformers for a given passband VSWR, but can have greatly superior shape factors in stripline and microwave-integrated-circuit (MIC) realizations. Hybrid meander-line transformers allow circuit designers greatly increased flexibility in choosing transformer shape factors, while allowing (basically) the same electrical performance as with either stepped-impedance or meander-line transformers. Experimental confirmations of a trial three-turn meander-line transformer and a fourth-order hybrid meander-line transformer are presented. A comprehensive design table of nearly equal-ripple meander-line transformers of from two to six turns, incorporating a wide range of bandwidths and impedance transformations has been deposited with the ASIS National Auxiliary Publications Service.     

Stepped-Impedance Transformers and Filter Prototypes

Quarter-wave transformers are widely used to obtain an impedance match within a specified tolerance between two lines of different characteristic impedances over a specified frequency band. This paper gives design formulas and extensive tables of designs, most of which were especially derived so that an integrated account could be presented for the first time. Numerous examples are given. Only homogeneous, synchronous transformers and filters are included in this paper, but a short bibliography on related topics is appended. The theory is also applied to band-pass filters, by showing how to convert quarter-wave transformers into half-wave filter prototypes. The theoretical and numerical results presented are applicable to the design of impedance transformers, direct-coupled cavity filters, short-line low-pass filters, optical antireflection coatings and interference filters, acoustical transformers, branch-guide directional couplers, TEM-mode coupled-transmission-line directional couplers, and other circuits. These applications have been or will be dealt with in separate papers; this paper gives the basic theory and some of the numerical data required for these applications.     

Analysis and Design Procedure of Transmission-Line Transformers

Transmission-line transformers are devices used to match RF and microwave devices, to make the conversion balanced-unbalanced, or both things simultaneously. Transmission-line transformers are mandatory at frequencies where traditional magnetic coupling transformers do not operate properly. In this paper, a procedure to design transmission-line transformers with different configurations is presented. The procedure is based on the theoretical analysis of the device and has been validated via experimental study.     

A high performance four port PIN diode switch for televisionbroadcasting applications

A double-pole change-over shunt PIN diode switch for television bands IV and V is described. The switch is characterized by low insertion loss, good isolation, and excellent VSWR over an operating bandwidth of 650-860 MHz. It is suitable as a drop-in device in existing repeaters, requiring no returning of the RF circuitry. Although not designed to switch high-power signals, the switch should easily handle 50-100 W CW signals. The design is based on a short-step distributed bandpass filter, resulting in a very compact transmission-line structure     

Unterwerks-Haupttransformatoren

Stationary main traction transformers represent the interface between the supraregional energy transportation network and the regional overhead contact lines feeding the electric traction vehicles and auxiliary plants in the supplied area of a single substation. Such transformers for traction purpose are subject to heavy peak-loads and frequent short circuits, but are also operated in underload conditions for long periods. These special service demands are of essential influence on their electrical and mechanical design. After a survey over those transformers run by the ÖBB the article describes the users needs and the resulting technical solutions of the manufacturer.     

Tables for Cascaded Homogeneous Quarter-Wave Transformers

Quarter-wave transformers are frequently required in microwave and UHF systems. An exact design procedure is known but involves lengthy calculations. Faced with the design of many such transformers, the calculations were programmed on an IBM 704 digital computer. The speed of computation is such that several hundred designs for 2, 3, and 4 section transformers were systematically computed in a few minutes. The results are reproduced here in tables, which should permit the calculation of most cases of practical interest by interpolation.     

无芯PCB 变压器的基本结构及其特性

本文主要介绍无芯印刷电路板变压器的基本概念、结构、特性。并介绍了无芯印刷电路板变压器的等效电路、电压增益、输入阻抗函数,同时说明了应用无芯PCB变压器的可靠性及其优点。无芯变压器消除了磁芯对频率、磁饱和度和磁芯损耗。运用现代化的印刷电路板技术,能够精确地控制印刷线圈的函数,易于大规模生产。它主要应用于高频的信号和能量转换,具有很大的应用潜能。     

Coreless planar printed-circuit-board (PCB) transformers-afundamental concept for signal and energy transfer

Magnetic cores have been used in transformers for over a century. In this paper, the authors present a fundamental concept of using “coreless” printed-circuit-board (PCB) transformers. With the aid of a high-frequency equivalent circuit, the use and basic characteristics of coreless PCB transformers are described. Optimal operating conditions for minimum input power requirement and maximum efficiency operations are identified. Coreless PCB transformers have the advantages of low costs, very high power density, no limitation due to magnetic cores, no magnetic loss and ease of manufacturing. They have the potential to be developed in microcircuits. A printed planar PCB transformer with a diameter of about 1.0 cm and power capability of 19 W has been successfully tested. The power density of the PCB transformer demonstrated in this paper is 24 W/cm². The maximum efficiency can be greater than 90%. The analysis has been confirmed with experiments. Coreless printed transformers have great potential in applications in which stringent height and space requirements have to be met     

Stepped transformers on TEM-transmission lines

The paper presents comparative analysis of the properties of impedance stepped transformers both with monotonous and nonmonotonous step-to-step impedance variation. A miniature stepped transformer of a new structure based on a cascade of an even number of uniform transmission line sections has been synthesized. Section lengths are considerably shorter than a quarter of the central wavelength, and the section impedances alternate. The proposed transformers are the simplest to implement among the available analogs. As an example, the results of the solution of the Chebyshev approximation problem for the four- and six-section transformers of different specifications are given     

有源型光学电流互感器研究进展

介绍了电子式电流互感器的分类,有源型电子电流互感器基本工作原理,回顾了近年来关于有源型电子式电流互感器研究的发展状况,着重介绍了使用Rogowski线圈进行采样的基本原理、利用悬浮电源、激光或太阳能电池的供电技术以及信号处理技术方面的研究进展。     

Frequency-Thermal Characterization of On-Chip Transformers With Patterned Ground Shields

Extensive studies on the performance of on-chip CMOS transformers with and without patterned ground shields (PGSs) at different temperatures are carried out in this paper. These transformers are fabricated using 0.18-mum RF CMOS processes and are designed to have either interleaved or center-tapped interleaved geometries, respectively, but with the same inner dimensions, metal track widths, track spacings, and silicon substrate. Based on the two-port S-parameters measured at different temperatures, all performance parameters of these transformers, such as frequency- and temperature-dependent maximum available gain (G_max), minimum noise figure (NF_min), quality factor (Q₁) of the primary or secondary coil, and power loss (P_loss) are characterized and compared. It is found that: 1) the values of the G_max and Q₁ factor usually decrease with the temperature; however, there may be reverse temperature effects on both G _max and Q₁ factor beyond certain frequency; 2) with the same geometric parameters, interleaved transformers exhibit better low-frequency performance than center-tapped interleaved transformers, whereas the center-tapped configurations possess lower values of NF_min at higher frequencies; and 3) with temperature rising, the degradation in performance of the interleaved transformers can be effectively compensated by the implementation of a PGS, while for center-tapped geometry, the shielding effectiveness of PGS on the performance improvement is ineffective     

A low-profile wide-band three-port isolation amplifier withcoreless printed-circuit-board (PCB) transformers

Galvanic isolations are essential in many electrical patient-monitoring devices and industrial applications. In this paper, a low-profile wideband three-port isolation amplifier using coreless printed-circuit-board (PCB) transformers for isolation is studied. The PCB thickness used in the isolation amplifier is 0.4 mm. The diameters of the two coreless PCB transformers are 9.75 and 5.856 mm, respectively. Operating conditions of the transformers and a design guideline of the isolation amplifier are detailed in this paper. Experimental results show that the isolation amplifier under investigation can transmit an analog signal from 20 mHz to 1.1 MHz with good linearity. Comparison of the prototype with an industrial isolation amplifier is also included     

Introduction to modeling of transformers and coupled inductors

A tutorial paper is presented on modeling and design of transformers and coupled inductors. Beginning with a brief review of electromagnetic laws and magnetic circuit models, the magnetic and electric models of transformers and coupled inductors are developed, including both magnetizing and leakage effects. It is shown that while the voltage waveforms on the windings are primarily related by the turns ratio for both devices, the winding currents of transformers and coupled inductors are determined by very different mechanisms. An integrated structure with both transformer and coupled inductor on the same core is also discussed, as well as the special case of the coupled inductor used on a multiple-output transformer-isolated converter     

Symmetrical and Asymmetrical Edge-Coupled-Line Impedance Transformers with a Prescribed Insertion Loss Design

Distributed element synthesis is used for obtaining edge-coupled-line impedance transformers. A gain factor is introduced in a characteristic transfer function representing a line and stub network. A redundant form of this network is identified with the equivalent circuit of the edge-coupled line pair. The transfer function is then used to synthesize Butterworth and Chebyshev coupled-line transformers. Design tables are presented for the symmetrical transformer. Transformation ratios different from unity are obtained only if the symmetrical structure is reflective. Asymmetrical transformers may exhibit nonunitary transformation ratios while being perfectly matched. Finally, applicability range is discussed.     

Passive Multiterminal Networks Without Transformers

It is known that any scalar function f(p) of the complex frequency variable that is the admittance function of a passive finite network is in fact the admittance function of a network that can be realized without transformers. This paper shows that an m times m matrix-valued function Y(p), m ges 2, given that it is an admittance matrix, is the admittance of a network that contains no transformers if and only if it enjoys two further properties: 1) for each real p > 0 Y(p) is the admittance of a passive resistive network specific to p; and 2) a property defined as the null space property. It is shown that property 1) severely limits the class of m-terminal networks, m > 1, that can be realized without transformers. The author concludes that, for passive systems, transformers are here to stay.     

计及特性阻抗不连续性的多频带多节变换器优化设计

 本文设计了计及特性阻抗不连续性的两频两节及三频三节变换器.基于理想传输线模型和微带传输线理论,建立了计及微带线"台阶"效应的设计方程,采用遗传算法实现优化设计,取得了在纯电阻源阻抗和负载阻抗以及随频率变化的源阻抗和负载阻抗两种情况下的两频两节及三频三节阻抗变换器设计参数.用ADS(Advanced Design System)商用软件对基于上述设计参数的微带电路进行电磁仿真的数值结果显示了该设计的有效性.     

Optimum Quarter-Wave Transformers

The design of uniformly dispersive quarter-wave transformers is a well explored subject. Common examples are rectangular waveguide E-plane transformers, in which the a dimension is kept constant. In this paper, it is shown that the performance of conventional quarter-wave transformers of a single section can always be improved by making the middle section less dispersive than the input and output waveguides, and a formula for the optimum a dimension is given. The theory was verified experimentally. In this instance, the improved transformer measured 50 per cent more bandwidth than did the conventional one, and was 25 per cent shorter besides.     

A low-profile low-power converter with coreless PCB isolationtransformer

Very small manually wound transformers for sub-watt DC-DC converters are notorious for their relatively high cost and low reliability. In this paper, an isolated low-profile low-power 8 MHz soft-switching power converter using a coreless printed circuit board (PCB) transformer is described. Coreless PCB transformers eliminate several problems of their core-based counterparts in low-power applications. The diameter of the coreless PCB transformer is merely 0.46 cm. The converter's power output is about 0.5 W with a typical transformer efficiency of 63%. The high-frequency capability, high reliability and the low-profile structure make coreless PCB transformers a viable and attractive option for reliable mega-hertz switching converters and micro-circuits