A study on stray capacitance modeling of inductors by using thefinite element method

Stray capacitance modeling of an inductor is essential for its RF equivalent circuit modeling and inductor design. Stray capacitance determines an inductor's performance and upper frequency limit. A method has been proposed for modeling the distributed stray capacitance of inductors by the finite element method and a node-to-node lumped capacitance network. The effects of wire insulation layer, ferrite core, number of segments used to model the circumference of a wire cross section, pitch and coil-to-core distances, and the capacitance between nonadjacent turns, etc., an an inductors' self-capacitance and calculation accuracy, have all been considered. The calculated equivalent lumped stray capacitance for a rod inductor with a ferrite core is compared to that estimated from measurement. Good agreement between them has been observed     

CHARACTERIZATION OF CAPACITIVE COUPLING FOR ON-CHIP CIRCULAR STACKED INDUCTORS

Capacitive coupling effects in some circular stacked inductors are studied in this paper, by taking into account the possible incomplete overlapping and cross-overlapping between up and bottom tracks of different layers. Formulas are derived for extracting the equivalent capacitance of double-and multi-spiral circular inductors with integral and fractional number of turns. Compared with the full-wave and the analytical methods with the completely overlapping assumption, the proposed method can predict equivalent capacitance and self-resonance frequency (f _SR ) accurately for on-chip circular stacked inductors used in the design of RFICs.     

电容器和电感器交流参数测量方法的对比研究

为了测量电容器和电感器的性能,常用的交流参数测量方法有传统模拟式（即电桥法和谐振法）和数字智能化测量方法两大类型。通过对比分析传统模拟式和数字智能化测量方法的基本原理和优缺点得出电感（电容）-电压的转换方法优点多,应用广,并指出电容器和电感器交流参数测量方法的发展趋势。     

Electromagnetic considerations in power electronic converters

Electromagnetic effects have an important influence on all aspects of power electronic design. The effects of stray magnetic and electric fields on circuit performance, and the necessity to control the resulting stray inductance and capacitance by good circuit design practices are introduced. Inductors are key components and the pressure to design to meet high-frequency specifications is relentless. Four types of inductors are discussed briefly and their electromagnetic properties are compared and contrasted. High-frequency transformers are discussed in terms of their impact on circuit behavior and their major design issues. The limitations of conventional topologies at multimegahertz frequencies are explored. A circuit example of a half-bridge series-parallel resonant converter working between 1-2 MHz and implemented using hybrid technologies is used to demonstrate how circuit, component and layout design are electromagnetically interdependent     

消除端电容对单片晶体滤波器影响的方法

为了解决晶体滤波器与电路前、后级有效匹配连接,并消除端分布电容的影响,提出了一种新的设计方法。该方法采用在滤波器的前后端装加匹配器,匹配器由电感和电容等不消耗有功功率的无功元件构成,因此不会对信号产生较大的传输损耗,也不会使通带特性变差。且匹配器可起到"隔离"分布电容的作用,大大减小分布电容对滤波器端部的影响,具有很好的应用价值。     

Improving the Characteristics of integrated EMI filters by embedded conductive Layers

Discrete electromagnetic interference (EMI) filters have been used for power electronics converters to attenuate switching noise and meet EMI standards for many years. Because of the unavoidable structural parasitic parameters of the discrete filter components, such as equivalent parallel capacitance (EPC) of inductors and equivalent series inductance (ESL) of capacitors, the effective frequency range of the discrete filter is normally limited. Aiming at improving high frequency performance and reducing size and profile, the integrated EMI filter structure has been proposed based on advanced integration and packaging technologies , . Some improvements have been made but further progress is limited by EPCs of the filter inductors, which is restricted by dimension, size and physical structure. In this paper, a new structural winding capacitance cancellation method for inductors is proposed. Other than trying to reduce EPCs, a conductive ground layer is embedded in the planar inductor windings and the structural capacitance between the inductor winding and this embedded layer is utilized to cancel the parasitic winding capacitance. In order to obtain the best cancellation effect, the structural winding capacitance model of the planar spiral winding structure is given and the equivalent circuit is derived. The design methodology of the layout and area of the embedded ground layer is presented. Applying this method, an improved integrated EMI filter is designed and constructed. The experimental results show that the embedded conductive layer can effectively cancel the parasitic winding capacitance, hence ideal inductor characteristics can be obtained. With the help of this embedded conductive layer, the improved EMI filter has much smaller volume and profile and much better characteristics over a wide frequency range, compared to the former integrated EMI filter and the discrete EMI filter.     

Quasi-static analysis of circular signal tapping pads

In this paper, analytical expressions for the capacitance of signal tapping pads are derived using a quasistatic analysis. The theory is validated by comparing our results with those of a commercial software package. As an application-oriented example, a new lowpass filter design is proposed which combines the signal tapping pads with lumped inductors.     

Band-pass filters with linear phase

A set of techniques has been developed which permits the simultaneous realization of flat pass band transmission (±0.15 db experimental) linear phase (to within ±5° experimental) over most (1 - 1/N) of the nominal pass band, where N is the number of "in-band" poles. Outside the pass band, the attenuation skirts are steep; experimentally, 40 db has been obtained within 1/N of the nominal filter bandwidth. Shunt L and/or stray capacitance are easily taken into account in the design; in particular, crystals as well as lumped LC have been used. The procedures can accommodate any amount of series resistance in inductors at the expense of flat loss, without any essential change in the computed values of inductors, capacitors, or resonant frequencies. The sensitivity of the network transmission to component errors is modest; discrepancies in the impedance level or tuning of a given constituent resonance in the network branches affect the characteristic mainly in the vicinity of that resonance.     

Determination of the constants of the capacitance/voltage law of a varactor diode

A graphical method is proposed for finding the constants, including the stray capacitance, of the capacitance/voltage relationship of a varactor diode.     

Exact solution for capacitive compensation of the RC potential divider with lumped stray capacitances to earth

Serious shortcomings of RC wideband dividers for high voltages can be overcome by suitably graded compensation of stray capacitance. The general case of the lumped-circuit-element RC divider is analysed, and the exact solution for graded capacitive compensation for any distribution of lumped stray capacitance is given.     

用分布电容模型分析和优化差分电感

建立了预测片上等效寄生电容的片上电感分布电容模型.预测和解释了差分电感的自激振荡频率的差异.实测数据显示,与单端驱动模式下的相同对称电感相比,差分驱动模式电感提高最大品质因数127%,具有更大的工作频率范围.设计和验证了低寄生电容的差分电感.     

Analysis and Optimum Design of Differential Inductors Using Distributed Capacitance Model

A distributed capacitance model for monolithic inductors is developed to predict the equivalently parasitical capacitances of the inductor.The ratio of the self-resonant frequency (fSR) of the differential-driven symmetric inductor to the fSR of the single-ended driven inductor is firstly predicted and explained.Compared with a single-ended configuration,experimental data demonstrate that the differential inductor offers a 127% greater maximum quality factor and a broader range of operating frequencies.Two differential inductors with low parasitical capacitance are developed and validated.     

一种改进光探测器高速性能的新方法

研究了一种在光探测器的结构设计中加入平面螺旋电感从而提高光探测器高速性能的新方法。对影响探测器频率响应的因素进行分析,结果表明,增加电感值可以减小结电容对高速性能的限制,仿真结果也得到同样的结论。根据理论分析结果制作出探测器并进行测量,测量数据显示,未加电感的光探测器高速性能只能达到2GHz,而加电感的光探测器高速性能最大,可以达到5GHz,证明了电感值的增加可以明显提高器件的高速性能,得到了与理论分析一致的结果。     

On the frequency limitations of SC filters

Representative closed-form expressions are derived for a stray-insensitive integrator which describe the combined influence of the amplifier finite gain and finite bandwidth and of the nonzero on-resistance of the switches. In this way, a technology-dependent upper frequency limit is obtained for the application of typical stray-insensitive switched-capacitor circuits. The deteriorating effect of switch-on resistance and stray capacitance is also derived for integrator circuits comprising unity-gain amplifiers. However, the results obtained shown that they are too much affected by the parasitic capacitances to be a serious alternative for monolithic high precision filters.     

空间光学系统的杂散光分析

介绍了空间光学系统的杂散光的来源,以及对红外光学系统成像质量的影响。在简化分析的基础上,讨论了杂散光分析的物理模型。利用已有的光学系统模型讨论了杂散光的计算和分析方法。主要介绍了蒙特卡罗法和光线追迹法在解决问题方面的作用,用具体的系统模型说明了杂散光计算和分析的假设条件、模型建立和计算过程等。对空间光学系统的杂散光有基础的认识。为以后利用软件进行杂散光分析打下基础。     

Physical modeling of spiral inductors on silicon

This paper presents a physical model for planar spiral inductors on silicon, which accounts for eddy current effect in the conductor, crossover capacitance between the spiral and center-tap, capacitance between the spiral and substrate, substrate ohmic loss, and substrate capacitance. The model has been confirmed with measured results of inductors having a wide range of layout and process parameters. This scalable inductor model enables the prediction and optimization of inductor performance     

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.     

New phase-shifting technique for group-type unidirectional transducers used in surface-acoustic-wave filters

The letter reports a novel method of phase shifting useful in the group type of unidirectional transducers used for the design of low-loss SAW filters. This technique utilises the thin-film capacitance present between the newly described configuration of the feed-electrode layers as an essential element of the required phase shifter. The stray capacitance existing between the feed electrodes is used to advantage. The theoretical and experimental results of one of the filters fabricated are presented.     

Effect of shunt capacitance on tapered distributed RC network characteristics

The effect of stray shunt capacitance on the characteristics of distributed RC networks, particularly in MOS integrated form, is considered. It is shown that the expected superiority of the tapered network over the uniform network in giving lower attenuation for a given phase shift is unlikely to be physically realisable because of the greater sensitivity of the former to the effect of stray shunt capacitance.     

Analysis of on-chip spiral inductors using the distributed capacitance model

In this paper, a distributed capacitance model (DCM) for monolithic spiral inductors is developed to predict the equivalent coupling capacitances C/sub p/ between the two terminals and the equivalent capacitance between the metal track and the substrate C/sub sub/. Therefore, the characteristics of inductors such as the S parameter, the quality factor Q, and the self-resonant frequency f/sub SR/ can be predicted by its series inductance, equivalent capacitances, and series resistance. A large number of inductors have been implemented in 0.25- and 0.35-/spl mu/m CMOS processes to demonstrate the prediction accuracy. For planar and multilayer inductors, DCM can provide a quick and accurate assessment to the design of monolithic spiral inductors.