圆形螺旋线圈自感和分布电容的计算

提出了一种计算圆形螺旋线圈自感和分布电容的方法。在元件尺寸小于波长的准静态近似情况下用 Sommerfeld类型积分计算小段平面圆弧的自感和互感 ,然后用螺旋线方程对每一小段圆弧的自感和圆弧间的互感积分 ,算得螺旋线圈的自感。计算螺旋线圈分布电容时同样先计算出两小段同心圆弧间的电容 ,然后用螺旋线方程对其积分算得螺旋线圈的总分布电容。编制了相应的程序对多种情况下的螺旋线圈自感和分布电容进行了计算 ,计算与实验结果比较 ,有较好的一致性。与经验公式相比 ,计算自感的方法有更广的适用范围和对实验结果更好的逼近。而分布电容的计算方法比其它的方法大大减少了运算量。     

Reduction of Transient Far-End Crosstalk Voltage and Jitter in DIMM Connectors for DRAM Interface

The transient far-end crosstalk voltage and the crosstalk-induced jitter of dual in-line memory module (DIMM) connectors are reduced by about 80% by increasing the mutual capacitance between DIMM connector pins with the additional interdigitated-comb-shaped metal-stub patterns on the motherboard. It was confirmed by the far-end crosstalk voltage waveform measurements using TDR and the eye diagram measurements at the data rates of 15 Mbps, 100 Mbps, and 3 Gbps. This reduction technique can be applied to the connectors where the inductive coupling ratio is larger than the capacitive coupling ratio.     

On the Superposition of Inductive and Capacitive Coupling in Crosstalk-Prediction Models

An examination of traditional low-frequency crosstalk-prediction models is presented. From the exact solution of the transmission-line equations for a 3-conductor line, it is shown that superimposing crosstalk contributions due to mutual inductance and mutual capacitance between the two circuits is valid for a sufficiently small frequency. The widely held notion that one may superimpose the effects of both mutual and self elements ( inductance and capacitance) is shown to be incorrect.     

The Effect of Mutual Inductance and Mutual Capacitance on the Transient Response of Braided-Shield Coaxial Cables

A quantitative comparison is made of the importance of mutual inductance and mutual capacitance in the leakage of transient signals through the braid of a coaxial cable. The difference between mutual inductance and mutual capacitance coupling is vividly exhibited in the transient predictions. Comparisons of predictions to measurements made on a length of RG-214 test cable are also included.     

Unified AC model for the resonant tunneling diode

A physics-based model is shown to yield the small-signal equivalent circuit of the resonant tunneling diode (RTD) including an analytic expression for both the quantum inductance and capacitance. This model unifies previous models by Brown et al. for quantum inductance and by Lake and Yang for quantum capacitance, and extends the RTD SPICE model of Broekaert. The equivalent circuit has been fit to both current-voltage and microwave S-parameter measurements of AlAs-InGaAs-InAs-InGaAs-AlAs RTDs from 45 MHz to 30 GHz and over biases from 0 to 0.81 V. Good agreement between the model and measurement is shown.     

无隔模带磁控管谐振系统的理论分析与仿真

为了提高磁控管稳定性,需要研究各耦合因素对磁控管谐振频率及模式分隔度的影响。该文采用等效电路的方法,给出了无隔模带磁控管在电容、电感耦合下的谐振频率及模式分隔度的表达式,并分析谐振频率随模数的变化趋势及电感、电容耦合强弱对模式分隔度的影响。采用CST-MWS软件对不同阴极半径及顶盖高度的谐振系统的谐振频率进行仿真,并将仿真结果与理论结果进行对比。理论分析与计算机仿真表明,对于无隔模带磁控管谐振系统,电容耦合使谐振频率随模数的增大而增大,电感耦合使谐振频率随模数的增大而减小;两者分别通过增大和降低模频率从而增大模式分隔度,两者共同作用时模谱图取决于占主导地位的耦合因素。     

互连线串扰耦合噪声的ABCD矩阵模型

高频互连线间的相互耦合和相互感应是产生串扰的一个重要因素。已有文献利用二端口网络ABCD矩阵从理论上求出了耦合互连线阶跃响应,但该方法对互感描述不准确,导致计算复杂,且对串扰耦合噪声的估计不够准确。该文根据互感的基本定义,修改了原模型中互感的表示方法,提出了一个新的ABCD矩阵级联模型,对LTCC工艺互连线的串扰耦合噪声进行分析,并将得到的ABCD模型分析结果与ADS软件的仿真结果对比,验证了改进的ABCD模型的准确性。     

The effects of metals on a transcutaneous energy transmissionsystem

The effects of metal objects on the mutual inductance, self-inductance, and effective series resistance (ESR) of the coaxial coils of a transcutaneous energy transmission system (TETS) were investigated theoretically and experimentally. The theory considers a thin conducting sheet of infinite size aligned parallel to a current-carrying coil. Results of the theory indicate that coil parameters vary with the distance from the sheet to the coil. Changes in mutual and self inductance are independent of the conductivity and thickness of the sheet, with a larger percentage change for mutual inductance than for self inductance. Changes in ESR are proportional to the surface resistivity of the sheet. Experimental measurements using several aluminum sheets and a titanium alloy can in the presence of the TETS coils used for the Penn State artificial heart showed excellent agreement with the theory for inductance parameters and agreed within a factor of 2 for ESR measurements when skin effect was considered. It was generally observed that mutual inductance drops to 65% of its initial value as a metal sheet is moved to within 1-2 cm of the coil, while self-inductance drops to 80% of its initial value when the sheet is 2 cm from the coil. Measured changes in ESR tended to be higher than the calculated values with the discrepancy depending on distance to the metal object. Theory and measurements were extended to the case of lateral misalignment of the coils.     

Over GHz electrical circuit model of a high-density multiple line grid array (MLGA) interposer

The multiple line grid array (MLGA) interposer was recently introduced as a future high-density high-speed bonding method. In this paper, we introduce an electrical model and high-frequency characteristics of the MLGA interposer. The high-frequency electrical model was extracted from microwave S-parameter measurements up to 20 GHz as well as from fundamental microwave network analysis. For the parameter fitting process during model extraction, an optimization method was used. Several different types of MLGA interposers were designed, assembled and tested. The test vehicles contained coplanar waveguides, probing pads and an MLGA interposer structure. The height of the MLGA, the conductor shape inside the MLGA, and the dielectric insulator of the MLGA were varied. From the model, an MLGA with a height of 0.4 mm and a polymer dielectric insulator was found to have 203 pH of self inductance, 49 pH of mutual inductance with the nearest ground conductor line, and 186 fF of mutual capacitance. By reducing the height of the MLGA and by using an insulator with a lower dielectric constant, parasitic inductance and capacitance is further reduced. TDR/TDT simulation and measurement showed the validity of the extracted model parameters of the MLGA interposer. Circuit simulation based on the extracted model revealed that the MLGA interposer could be successfully used for microwave device packages up to 20 GHz and for high-speed digital device packages with a clock cycle up to 5 GHz.     

Inductor winding capacitance cancellation using mutual capacitance concept for noise reduction application

In this paper, the properties of mutual capacitance between two capacitors are first discussed. It is found that the effects of mutual capacitance can be represented by two positive or negative capacitors across the two capacitors. These two equivalent capacitors can be used to cancel the parasitic capacitance of inductors. Because the mutual capacitance can be emulated using two small capacitors, the proposed method can easily be implemented in practical components. The prototypes are then built and the cancellation is verified using a network analyzer. Further EMI measurements in a practical power circuit prove that there is a significant improvement in the inductor's filtering performance.     

Subthreshold parameters of radio-frequency multi-finger nanometer MOS transistors

The subthreshold radio-frequency (RF) characteristics of multi-finger nanoscale MOS transistors were studied by using the measured scattering (s) parameters. Small-signal circuit parameters were determined based on a simplified small-signal equivalent circuit model. We found that besides the source and gate resistances, most of the parameters such as the channel resistance, drain inductance and intrinsic capacitance are found to be significantly different to those in the saturation mode of operation. The subthreshold channel resistance increases and the drain inductance decreases as the finger number increases because of the more significant charge transport along the finger boundaries. In addition, the channel resistance can be governed by the drain-induced barrier lowering in a transistor with very short gate length. The equivalent intrinsic capacitance of the small-signal equivalent circuit is governed by the substrate resistance and capacitance which make the parameter extraction more difficult.     

Estimating the noise mitigation effect of local decoupling in printed circuit boards

Local decoupling, i.e., placing decoupling capacitors sufficiently close to device power/ground pins in order to decrease the impedance of power bus at frequencies higher than the series resonant frequency, has been studied using a modeling approach, a hybrid lumped/distributed circuit model established and an expression to quantify the benefits of power bits noise mitigation due to local decoupling developed. In this work, a test board with a local decoupling capacitor was studied and the noise mitigation effect due to the capacitor placed adjacent to an input test port was measured. Closed-form expressions for self and mutual inductances of vias are developed, so that the noise mitigation effect can then be estimated using the previously developed expression. The difference between the estimates and measurements is approximately 1 dB, which demonstrates the application of these closed-form expressions in the PCB power bus designs. Shared-via decoupling, capacitors sharing vias with device power/ground pins, is also modeled as an extreme case of local decoupling.     

Low-loss plastic molded optical multifiber connector for ribbon-to-single fiber fan-out

This paper describes a newly developed low-loss demountable multifiber connector for ribbon-to-single optical fiber fan-out. The connector plugs contain special gathering parts that make a high-density arrangement for monocoated optical fibers. Using a multi-V-grooved mold, the optical fibers are accurately positioned and then a plastic formation process is adopted to form the plug. Plugs are precisely aligned by using two pins. An average connecting loss of 0.07 dB has been achieved in the stationary mode distribution with index matching. The change in connecting loss did not exceed ± 0.03 dB when the connector was subjected to heat cycles in a temperature range of-30-+60degC.     

Microwave characterization of the properties and performance of GaAs Schottky barrier mixer diodes

Microwave measurements have been made of the equivalent circuit parameters and performance characteristics of unpackaged GaAs Schottky barrier mixer diodes. The dependence of mixer performance on series inductance, junction capacitance, and series resistance is delineated. Performance of mixer diodes in packaged and unpackaged form is compared.     

Empirical equations on electrical parameters of coupled microstriplines for crosstalk estimation in printed circuit board

Empirical equations for the self and mutual capacitance and inductance (C_s, C_m, L_s, L_m) of coupled microstrip lines in a printed circuit board were derived from the numerical simulation results to reduce the computation time for crosstalk estimation. Comparison of the measured C_s, C_m , L_s and L_m values with the derived empirical equations showed good agreements. Also in the near-end and far-end crosstalks, good agreements were obtained between measurements and the derived empirical equations. Microstrip lines embedded in the homogeneous dielectric material as well as those in the inhomogeneous medium with one side exposed to air were considered in this work. Based on the derived empirical equations, a design guide on the spacing between microstrip lines was established     

有互感和电源的电容耦合电路的量子涨落

通过正则变换和幺正变换的方法研究了有互感和电源存在的情况下的介观电容耦合电路的量子涨落。结果表明电荷和电流的量子涨落与电源无关。当电路元件确定时，如果L1／L2的值很大或很小，耦合对涨落的影响很大。互感从有到无的过程中，回路1中电流的涨落和回路中2中电荷的涨落有明显的变化。换句话说，互感的有无对涨落的大小起着举足轻重的作用。     

降低连接器内电磁干扰的方法分析

基于对任一接插件的干扰只来自最邻近接插件的假设,对连接器内部的电磁干扰建模,模型内接插件间的互耦电容用矩量法进行计算,根据模型的特点采用三角函数做匹配函数简化了计算过程并提高了计算精度.求出敏感接插件周围的接插件全部为信号线时的单位长度参数,不同状态的实现只需通过负载的调节即可,使对不同连接的模拟变得简单易行.对什么时候会在敏感件上产生最大和最小的干扰,以及周围信号的多少对干扰的影响都进行了讨论,以S参数和时域波形的形式给出模拟结果.模拟对正确地连接接插件,降低相互干扰有参考价值.     

静态场部分电容和互感的测量

多导体部分电容和互感是静态场中非常重要的两个概念.本文介绍了部分电容和互感的特性及测量原理,给出一种测试仪器,通过对具体参数的测试,所得的测试结果与理论计算结果相吻合.实践表明,两个实验系统的开发不仅可以促进学生综合运用所学知识的能力,也可激发学生对电磁场专业理论知识学习的兴趣.     

基于共面紧凑的宽带隙微波光子晶体研究

针对一般共面紧凑电磁带隙(UC-EBG)结构相对带宽较窄的问题,根据EBG结构的局域谐振原理和等效电路分析模型,对传统的UC-EBG结构进行了改进,提出了一种新型EBG结构。该结构通过引入弯曲折线延长了电流长度,增大了等效电感效应;采用了更长的边缘耦合,延长了等效磁流,增强了等效电容效应。实验结果表明,这种新型EBG结构在同样紧凑的尺寸下,(带隙)的相对带宽可达40.9%～45.2%,比文献结构提高了约14.6%～18.9%,实现了紧凑宽带隙UC-EBG的设计目的。     

Traces in proximity to gaps in return planes

Coupling between circuitry on printed circuit boards can be mitigated by a variety of well-known techniques. One such technique is to isolate circuitry in different areas of the printed circuit board by strategically placing a gap in the signal return plane. However, this technique is only effective at reducing common-impedance coupling, which is generally not a significant coupling mechanism at frequencies above 1 MHz. This paper investigates the effect of a gap located between and parallel to adjacent microstrip traces. The effect of the gap on the mutual inductance and mutual capacitance is evaluated. Laboratory measurements and numerical simulations show that gaps in the return plane are ineffective at reducing inductive and capacitive crosstalk in most configurations, and in some cases they increase the mutual coupling between printed circuit board traces.