Low cost flex substrates for miniaturized electronic assemblies

Electronic power converters have been designed, produced, and disseminated to the market in mass quantities utilizing a number of fabrication techniques; ranging from standard printed circuit board (PCB) technologies for low cost applications, to conventional thick film on ceramic, to direct bond copper (DBC) approaches for high power, higher cost applications. Each of these approaches holds a share of the power packaging market, but they all demonstrate a limitation to conventional two dimensional “flat board” strategy. PCBs, thick films, and DBCs are all technologies which restrict, for the most part, circuit and package designs to two dimensional boards. The one potential pathway into the third dimension is through the use of multilayers; an approach, which becomes increasingly difficult with each additional layer added beyond the first, and with the exception of high performance solutions is typically cost prohibitive for the majority of applications.This paper will demonstrate the feasibility and viability of flexible polymer substrates. Flex technology employs industry standard PCB and/or thick film processes, offers the lower cost, higher performance solutions inherent with the majority of polymer plastics, and as a final bonus, essentially frees the designer to more efficiently utilize all three dimensions of space. The researchers have demonstrated the feasibility of this low cost alternative solution through the fabrication and testing of integrated power modules, which utilize flexible polymer substrates in conjunction with both surface mount and bare dice. These DC/DC power converters transform 120 V/240 V inputs to 9 V, 7-W outputs, and illustrate through their unique geometrical design the miniaturization advantages of fully utilizing the three dimensional space offered by flex circuitry.     

Copper-based hybrid fabrication of a 50 W, 5 MHz 40 V-5 V DC/DCconverter

A prototype 50 W, 40 V to 5 V DC/DC converter operating at 5 MHz and constructed with chip and wire hybrid techniques on a ceramic substrate with copper thick-film conductors is presented. A brief discussion of the thick-film process is given to point out the special issues concerning copper-based conductor systems. Some of the specific trade-offs that arise with regard to the construction of a power circuit with hybrid techniques are discussed. A method by which transformers may be fabricated to have very little leakage inductance, both internally and in their connection to rectifiers, is then described. The performance of a power circuit, the dual resonant forward converter is presented     

Pyxos嵌入式网络中链路电源模块的设计

为了降低Pyxos嵌入式网络的成本、占用空间和使用的复杂性,介绍了链路电源技术在Pyxos嵌入式网络中的应用。利用电源变压器、整流滤波电路、稳压电路和直流电源滤波器所设计的链路直流供给电源模块向网络供给24V直流电;利用交流滤波电路和电源变压器所设计的链路交流供给电源模块向网络供给24V交流电。链路节点电源模块采用低通滤波器将同一电缆同时传输电源信号和数据信号的电源信号输入Pyxos节点并通过线性电源电路向Pyxos芯片提供3.3V的工作电压。为保证网络性能可靠,还提出了确定Pyxos节点与链路供给电源模块的距离的方法。实际应用表明链路电源技术降低了设备的安装时间和成本。     

Photonic integration for high-volume, low-cost applications - [Topics in optical communications]

To date, photonic integration has seen only limited use in a few optical interface applications. The recently adopted IEEE draft standards for 40 Gb/s and 100 Gb/s Ethernet single-mode fiber local area network applications will change this situation. Although first generation implementations will use discrete components based on existing technologies, long-term requirements for significant reduction in cost, size, and power of 40 Gb/s and 100 Gb/s transceivers will lead to a broad demand for photonic integration. Both hybrid planar lightguide circuit and monolithic photonic integrated circuit are feasible approaches that meet the requirements of the new IEEE standards.     

新型磁耦合隔离电路设计

在电路设计中,数字信号的隔离传输电路是比较常用电路之一,一般的磁耦合隔离电路只适合于传输高频信号,对于低频或直流信号则无能为力。为了实现磁耦合隔离电路传输低频信号的功能,用一串窄脉冲代表数字信号的状态改变,以窄脉冲的磁隔离传输代替低频数字信号的磁隔离传输,以上电复位电路确定磁隔离传输电路的初始状态,在确定的初始状态和信号状态变化脉冲的共同作用下,在磁隔离电路的输出端完整恢复需要传输的数字信号,从而实现低频或直流信号的磁耦隔离传输。使用该设计可以拓展磁耦合隔离技术的应用领域,降低电路功耗。     

基于UC3844的反激式开关电源设计

电源的优劣直接影响到各类电子设备的性能,文中设计了一款性能优良的开关电源。该电源控制电路以UC3844为核心进行设计;DC/DC变换主电路采用单端反激式电路;电源电压反馈部分采用典型的TL431加光耦PC817。实验结果表明该电路效率高,输出稳定,性能优越,成本相对较低。     

Integrated magnetic full wave converter with flexible output inductor

A new integrated magnetic full wave DC/DC power converter that provides flexible transformer design by incorporating an independent output inductor winding is introduced. The transformer is implemented on a traditional three-leg magnetic core. The inductor winding can be separately designed to control the output current ripple. The cross-sectional area of the inductor core leg can be reduced dramatically. The operation and performance of the proposed circuit are verified on a 100 W prototype converter.     

Improved analysis method for multiport microstrip annular-ringpower-dividers

An improved analysis method for multiport microstrip annular-ring power-dividers is presented which is essentially based on the planar circuit theory assuming magnetic walls at conductor edges. The generalized impedance matrix of the power-dividers is evaluated using two approaches, the Green's function approach and the circular harmonic function approach. The concept of effective dimensions is adopted for taking into account fringing fields to compensate the planar circuit theory. The properties of the power-dividers can be controlled by varying the width of the conductor ring in contrast to those of disk structures. Characteristics of a four-port power-divider in the form of microstrip lines calculated with the present approach are in good agreement with experimental data     

一种光伏模拟电源的设计

为给被测试的光伏逆变器提供一个测试其最大功率点性能的环境,设计了一种光伏模拟电源。其主要由整流滤波电路和DC/DC电源组成。整流滤波电路将交流电变成直流,开关电源部分完成降压功能,通过将输出电压采样送入误差比较器中与控制器RAM中的电压进行比较,来控制输出电流和电压,使其工作在对应的I-V曲线上。文中设计的光伏模拟电源可人为地输入温度和日照来模拟太阳能光伏曲线。     

Finite-element analysis of copper loss in 1-10 MHz transformers

Issues related to the copper loss in the planar windings of 1-1 MHz power transformers are discussed. The relationship between current distribution, copper loss, and core geometry is investigated with the aid of finite-element analysis. Magnetizing current proximity effects are shown to cause excessive copper loss in a simple sandwich transformer, a structure formed by sandwiching the planar winding between two plates of magnetic material. Three alternative transformer structures that reduce this problem are compared. These alternative structures are: the cofired transformer, the slotted gapped transformer, and the slotted ungapped transformer. It is concluded that a slotted transformer design should be used if the magnetizing current is relatively large. Both a slotted gapped and a slotted ungapped design relies strongly on the exact permeability of the material and may suffer from higher core losses because all of the energy is stored in the magnetic material, rather than in an air gap. In either case, the depth of the slot should be About 40% of its width     

单片机控制的直流PWM调速装置的研究

与交流电动机相比，直流电动机结构复杂，成本高，运行维护困难。但是直流电动机具有良好的调速性能、较大的起动转矩和过载能力强等许多优点，因此在许多行业中仍有应用。文章介绍了一种利用单片机控制的PWM调速装置实现小功率赢流电动机调速的方法，具体详述了电路的设计思想、电路的组成以及工作原理。     

Low stray inductance bus bar design and construction for good EMCperformance in power electronic circuits

Ten years after the publication of the EC Directive 89/336 on electromagnetic compatibility, the impact of this directive on design and lay-out of modern electrical and electronic equipment can be observed. Many research and development studies have proposed and evaluated detailed improvements in the area of component design, component selection, circuit lay-out, shielding and active and passive filtering. New and innovative solutions to minimize noise, especially common mode conducted electromagnetic interference (EMI), in power electronic circuits continue to be developed. In this paper, the authors investigate to what extent EMI caused by power electronic devices in hard switching inverter topologies can be minimized using ultra-low inductive planar busbars. The concept followed in this study is to tackle EMI directly at the source where most EMI is generated; in other words, to reduce the parasitic magnetic energy stored in the inverter DC link to reduce high voltage spikes during switching. A planar busbar was built, tested and analyzed. Measurements show the validity of the theoretical, but simple, design procedure for planar busbars in power converters     

Some electromagnetic aspects of coreless PCB transformers

In this paper, some EMI aspects of using coreless PCB transformers are addressed. Based on the antennas theory, the radiated power of a coreless PCB transformer is estimated and found to be negligible. The electromagnetic field plot of a power electronic circuit using a gate drive circuit isolated by a coreless PCB transformer has been recorded. The major radiated EMI source in the frequency range of 30 MHz to 300 MHz is found to be the copper tracks of the power circuit, where switching transients occur, rather than the coreless PCB transformer. Coreless PCB transformers essentially operate at relatively low frequency (8 MHz in this case) by near-field magnetic coupling. Experimental results have confirmed that the application of coreless PCB transformer in gate drive circuit will not impose any serious EMI problem on the power electronic circuit     

Improving signal integrity in circuit boards by incorporatingembedded edge terminations

Much attention has been paid toward signal and power integrity in devices, circuit boards and entire systems. Resonances set up between the power and ground planes due to multiple reflections from the edges of the circuit board will affect signal integrity. The impedance seen by a via passing between the power and ground planes can be very high at the resonant frequencies. This gives rise to the effects of crosstalk and simultaneous switching noise (SSN) which would adversely effect the operation of the device. An attempt has been made in this paper to cover all the topics in earlier papers (Shi et al., Proc. Electron. Comp. Technol. Conf., 2001, and Adsure et al., Proc. IPAC'01 Conf., 2001), which describe a method to incorporate lossy (absorbing) material at the edges of a circuit board to reduce the wave reflections. The "lossy material" is usually a material of very high resistivity but which shows large magnetic losses at UHF and microwave frequencies. Thus this material is suitable to be placed directly between the power and ground planes without introducing any DC leakage currents. Experiments were carried out on a bare copper circuit board with FR-4 dielectric. The absorber used in the experiments is available commercially in flexible, castable and hard dense forms. It is shown that it is possible to reduce the impedances at the resonant frequencies to quite an extent over a broad frequency band by applying the lossy material at the edges of the board. Various configurations of applying the material are also described     

Multifunction SAG process for high-yield, low-cost GaAs microwaveintegrated circuits

A new fully planar, multifunction refractory self-aligned gate (MSAG) technology suitable for the fabrication of GaAs small-signal and power microwave monolithic integrated circuits (MMICs) is demonstrated in a manufacturing environment. Data on the distribution of DC and RF performance and yield for pilot production of discrete FETs and MMICs are presented. The heart of the MSAG process is a planar, self-aligned gate FET. It uses a refractory TiWN Schottky gate and exhibits high performance for small-signal microwave, power microwave, and digital circuit applications. Lots with good wafer yields have demonstrated average chip yields on PCM good wafers of 45%, 49%, and 36% for 2-10-GHz distributed amplifiers, 1-W C-band power amplifiers, and 4-W power amplifiers, respectively     

PCB integrated inductors for low power DC/DC converter

This paper discusses the use of printed circuit board (PCB) integrated inductors for low power DC/DC buck converters. Coreless, magnetic plates and closed core structures are compared in terms of achievable inductance, power handling and efficiency in a footprint of 10 /spl times/ 10 mm/sup 2/. The magnetic layers consist of electroplated NiFe, so that the process is fully compatible with standard PCB process. Analytic and finite element method (FEM) methods are applied to predict inductor performance for typical current waveforms encountered in a buck converter. Conventional magnetic design procedures are applied to define optimum winding and core structures for typical inductor specifications. A 4.7 /spl mu/H PCB integrated inductor with dc current handling of up to 500 mA is presented. This inductor is employed in a 1.5 W buck converter using a commercial control integrated circuit (IC). The footprint of the entire converter measures 10 /spl times/ 10 mm/sup 2/ and is built on top of the integrated inductor to demonstrate the concept of integrated passives in power electronic circuits to achieve ultra flat and compact converter solutions.     

通信局房直流供电系统应用技术革新

针对-48V直流供电系统中存在的输电问题,文章提出了一个解决思路,即在传统直流供电系统上增加直流升/降压系统,提高输电电压,降低回路压降。该方法能减少电缆的使用,降低铜耗、节约能源。     

Reduction of high-frequency conduction losses using a planar litz structure

A new trend in power converters is to design planar magnetic components that aim for low profile. However, at high frequencies, ac losses induced in the planar inductor and transformer windings become significant due to the skin and proximity effects. A planar litz conductor can be constructed by dividing the wide planar conductor lengthwise into multiple strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire conductor. Each strand is then equally subjected to the magnetic fields in the winding window, thereby equalizing the flux linkage and improving the current distribution. Three-dimensional finite-element modeling was performed for simple models. The simulation results showed that the planar litz conductor can result in lower ac resistance than a solid conductor over a specific frequency range. The performance of the planar litz winding was also verified with measurements on two experimental prototypes.     

Power harvesting with PZT ceramics and circuits design

Power generated from a piezoelectric material usually comes with poor characteristics such as high voltage, low current and high impedance. In order to drive the embedded sensor circuit, piezoelectric power needs to be characterized and regulated. In this paper, we present an analysis on the power generation characteristics and the efficiency of power conversion of the stiff lead zirconate titanate (PZT) ceramics. Moreover, a power circuit design is put forward in the application where PZT elements are used for power generation in a TKR implant. A hybrid direct current (DC)–DC, comprising a switched capacitor (SC) DC–DC converter and a low dropout (LDO) linear voltage regulator, is presented. The variable ratio SC converter has been taped out with 0.35 μm CMOS technology. The test results show that the SC converter can transfer the input voltage that ranges from 5 to 14 V from the PZT ceramics into the voltage ranging from 2 to 2.5 V which will be dealt with by LDO circuit whose efficiency can reach 80%.     

一种薄膜PCB平面变压器的研究

采用现代化印刷版技术,首先设计制作出一种基于柔性PCB板、线圈宽度为0.2mm、线间距为0.3mm、匝数比为6:18的空心变压器,然后采用直流磁控溅射在其上下表面镀上软磁薄膜,而最终制成了一种薄膜PCB平面变压器。研究了薄膜材料、膜厚等因素对该种变压器性能的影响。结果表明,制得的薄膜PCB平面变压器可以有效工作于4～14MHz的频率范围。采用上述方法制备变压器,可以把变压器从三维变成两维,从而为器件的表面贴装打下基础,并同时满足"更小,更轻,更薄"的要求。