Impact of partial element accuracy on PEEC model stability

This paper details the impact of partial element accuracy on quasi-static partial element equivalent circuit (PEEC) model stability in the time domain. The potential sources of inaccurate partial element values are found to be poor geometrical meshing and the use of unsuitable partial element calculation routines. The impact on PEEC model stability of erroneous partial element values, and the coefficients of potential and partial inductances, are shown as theoretical constraints and practical results. Projection meshing, which is a discretization strategy suitable for the PEEC method, is shown to improve calculated partial element values for the same number of unknowns, thus improving model stability.     

A scaling technique for partial element equivalent circuit analysis using SPICE

A scaling technique for partial element equivalent circuit (PEEC) analysis using SPICE is introduced in this letter. The perturbation series based scaling is applied to the component values extracted by the standard PEEC method to get up to an order of magnitude improvement in relative accuracy of scattering parameters with SPICE simulation. The effectiveness of the technique is verified by using the numerical example of a stripline structure and comparing the results with that of the method of moments (IE3D).     

Stability of discretized partial element equivalent EFIE circuitmodels

The instabilities associated with integral equation techniques for-the solution of electromagnetic problems in the time domain are well known. Instabilities may be due to either the numerical technique used for the time integration, or problems created by the discrete representation for the numerical solution of the problem. In this paper, we concentrate on the discretization issue. The stability problem occurs for various discretizations and formulations. Here, we use the partial element equivalent circuit (PEEC) formulation of the electric field integral equation (EFIE) in the circuit domain. This leads to a better understanding of the issues at hand. We show why the discretized model can be unstable and we suggest a circuit motivated technique to stabilize the solution     

基于等值回路平衡方程的变压器保护原理

本文针对等值回路平衡方式的变压器保护原理及相关问题进行分析.     

Fuzzy logic and equivalent circuit approach to rain measurement

The design and practical results of a simple rain sensor designed to detect and measure different levels of precipitation are presented. The sensor satisfactorily yields analogue measurement of precipitation suitable for use in conjunction with automated control systems, for example automotive systems, automated windscreen wipers and headlight systems.     

Accuracy of simplified printed circuit board finite element models

Electronic components are prone to failure due to shock or vibration loads. To predict when this failure may occur it is necessary to calculate the vibration response of the printed circuit board (PCB); this is most usually achieved through use of simplified finite element (FE) models. The accuracy of these FE models will be mainly dependant on various sources of error, including: manufacturing variability, which will cause supposedly identical printed circuit boards to behave differently (including variability in materials and assembly, as well as dimensional tolerances); inaccuracy in the model input parameters, which is caused by either the modelling assumptions used or poor measurement technique; and errors in the solution process (e.g. linear solutions in non-linear situations). This paper investigates experimentally the contribution of these effects, this is achieved by first looking at measurement of input parameters and to what accuracy a PCB can reasonably be modelled, and then secondly measuring the extent of manufacturing and assembly induced variability. When these contributions have been defined, it will be possible to assess the confidence in any FE PCB model.     

Design of dual-frequency SRR-loaded dipole with equivalent circuit approach

An equivalent circuit approach to design dual-frequency printed dipoles is presented. This approach is based on magnetic coupled circuit characterising an antipodal printed dipole loaded with split ring resonators (SRRs). This kind of antenna allows working with any arbitrary pair of frequencies, and the equivalent circuit predicts accurately the two resulting resonance frequencies, as well as their bandwidth. Two prototypes, one working at 1.32 and 2.83 GHz and the second working at 1.2 and 2.05 GHz. have been manufactured and measured, showing excellent agreement with simulations and reasonable values for efficiencies at both frequencies.     

Improved small-signal equivalent circuit model and large-signalstate equations for the MOSFET/MODFET wave equation

A simple non-quasi-static small-signal equivalent circuit model is derived for the ideal MOSFET wave equation under the gradual channel approximation. This equivalent circuit represents each Y-parameter by its DC small-signal value shunted by a (trans) capacitor in series with a charging (trans) resistor. A large-signal model for the intrinsic MOSFET is derived by first implementing this RC topology in the time domain. Modified state equations are then introduced to enforce charge conservation. Transient simulations with this approximate large-signal model yield results that are compared with reported exact numerical analysis for the long channel MOSFET for a wide range of bias conditions. This unified small- and large-signal model applies to both the three- and four-terminal intrinsic MOSFET in the region of the channel where the gradual channel approximation is applicable. A non-quasi-static small-signal equivalent circuit for the velocity-saturated MOSFET wave equation is also reported     

On the stability of time-marching schemes for the general surfaceelectric-field integral equation

We demonstrate that time marching algorithms which use the electric-field integral equation to compute the current induced on a perfect conductor by a transient electric field, may have unstable modes that are due to the particular basis functions used to represent the current on the conductor. These modes are not removed by averaging the solution in time, but they can be eliminated by averaging in space appropriately     

Origins of the equivalent circuit concept: the voltage-source equivalent

This paper describes the development of the voltage-source equivalent circuit. A subsequent paper concerns the current-source equivalent and summarizes the story. The formal roots of equivalent circuits are Ohm's Law, Kirchoff's Laws, and the Principle of Superposition.     

Origins of the equivalent circuit concept: the current-source equivalent

The voltage-source equivalent was first derived by Hermann von Helmholtz (1821-1894) in an 1853 paper. Exactly thirty years later in 1883, Leon Charles Thevenin (1857-1926) published the same result, apparently unaware of Helmholtz's work. The generality of the equivalent source network was not appreciated until forty-three years later. Then, in 1926, Edward Lawry Norton (1898-1983) wrote an internal Bell Laboratory technical report that described in passing the usefulness in some applications of using the current-source form of the equivalent circuit. In that same year, Hans Ferdinand Mayer (1895-1980) published the same result and detailed it fully. As detailed subsequently, these people intertwine in interesting ways.     

基于小信号等效电路模型的HBT本征稳定性研究

本文基于小信号等效电路模型,对异质结双极晶体管的本征稳定性进行了分析和讨论。稳定性因子（即K因子）用于评估器件的高频稳定特性。基于HBT的T型等效电路模型,推导了K因子的理论分析公式,并全面分析了小信号模型中物理参数对器件本征稳定性的影响,得到了提高器件本征稳定性的物理参数优化设计方法。测试计算了多个不同物理参数的HBT样品的稳定性因子K。物理参数对器件稳定性影响的实验结果与理论分析的影响规律一致。     

Time domain integral equation approach for inhomogeneous and dispersive slab problems

A numerical approach is described, based on a rigorous integral formulation, to the problem of an inhomogeneous dispersive slab illuminated by incident TEM plane wave with arbitrary time dependence. The slab is assumed to be nonmagnetic and its complex permittivity only varies normally to its interfaces. The numerical process consists of a space-time discretization. The solution can be determined step by step from simple recurrence formulas. Some examples are given for normal incidence in order to illustrate the most interesting features of the method and its possible field of applications.     

Characteristic-function approach to parameter extraction for asymmetric equivalent circuit of on-chip spiral inductors

A novel approach to parameter extraction for an asymmetric equivalent circuit of silicon-on-chip spiral inductors based on measured S-parameter is proposed. The current methodology is based on the linear dependence of a set of characteristic functions on other functions or variables such as /spl omega//sup 2/ in a certain frequency range, and the model parameters can be derived from the corresponding linear coefficients. As applied to an asymmetric single-/spl pi/ equivalent circuit, the extracted parameters can simulate the inductor with a high precision up to 10 GHz.     

Direct computation of expected numbers of failures and repairs via integral equation approach

This paper develops a method for computing the expected number of failures and the expected number of repairs of a component in a prescribed time interval. Our method computes directly the above mentioned quantities without passing through a conventional step of calculating the unconditional failure and repair intensities over the corresponding time interval. Our method is constructed via integral equation formulation with its operator equation representation. It is shown that the expected number of failures and the expected number of repairs can be computed with the same precision of accuracy as that of the unconditional failure and repair intensities, which cannot be possible by a conventional approach.     

Coupling finite element and integral equation solutions usingdecoupled boundary meshes [electromagnetic scattering]

A method is outlined for calculating scattered fields from inhomogeneous penetrable objects using a coupled finite element-integral equation solution. The finite element equation can efficiently model fields in penetrable and inhomogeneous regions, while the integral equation exactly models fields on the finite element mesh boundary and in the exterior region. By decoupling the interior finite element and exterior integral equation meshes, considerable flexibility is found in both the number of field expansion points as well as their density. Only the nonmetal portions of the object need be modeled using a finite element expansion; exterior perfect conducting surfaces are modeled using an integral equation with a single unknown field since E _tan is identically zero on these surfaces. Numerical convergence, accuracy, and stability at interior resonant frequencies are studied in detail     

On the equivalent circuit of a receiving antenna

The equivalent circuit of a receiving antenna consists of a current generator and two admittances: one for the load, and one for the antenna. The short-circuit current, I_g - receiving property - may be expressed in terms of the transmitting properties of the antenna. The article gives a derivation for the value of I_g. It is assumed, to simplify matters, that the antenna is located in free space, and that its feeding line is a monomode waveguide (a coaxial cable, for example). The extension to multimode lines, or to spatial regions containing linear media (possibly anisotropic, and/or non-reciprocal) is fairly straightforward     

Broad-band determination of the FET small-signal equivalent circuit

A method to determine the broadband small-signal equivalent circuit of field-effect transistors (FETs) is proposed. This method is based on an analytic solution of the equations for the Y parameters of the intrinsic device and allows direct determination of the circuit elements at any specific frequency or averaged over a frequency range. The validity of the equivalent circuit can be verified by showing the frequency independence of each element. The method can be used for the whole range of measurement frequencies and can be applied to devices exhibiting severe low-frequency effects