Electric

L'utilizzo sempre più frequente di circuiti digitali nei circuiti elettronici ha evidenziato la necessità di stimare in modo preciso la forma d'onda della corrente di segnale nei circuiti stessi al fine di predire le emissioni elettromagnetiche, la diafonia ed il “power-bus noise” nei circuiti stampati.

ABSTRACT Hybrid FEM/MoM methods combine the finite element method (FEM) and the method of moments (MoM) to model inhomogeneous unbounded problems. These two methods are coupled by enforcing field continuity on the boundary that separates the FEM and MoM regions. Hierarchical higher-order tangential vector finite elements (TVFE's) are of practical interest because they can be easily combined with low-order elements to improve the accuracy of numerical solutions.

Abstract Automotive components are subjected to a variety of electromagnetic compatibility tests before they are ever installed on a vehicle, and yet the correlation between component-level EMC test results and vehicle-level EMC performance is generally poor. As automobiles become more reliant on electronic systems to ensure the reliable operation of the vehicle and the safety of its occupants, full-vehicle electromagnetic simulations are becoming an increasingly important part of the automotive design process.

Abstract At the 2000 IEEE International Symposium on EMC, a paper was presented by Y. Ji et al.(paper appears in 2001 proceedings) that compared the application of PEEC and MOM techniques to the analysis of one of the EMC Society/Applied Computational Electromagnetics Society special challenge problems. Good agreement was obtained between the two codes at 2 out of the 3 measurement ports. At that time, no definite explanation was provided for the discrepancy at the third port.

Abstract—The automobiles of the future are being designed on computers and a significant amount of performance and safety testing is done using computer models. By the time the first hardware prototype is built, many critical design decisions affecting intersystem and intra-system electromagnetic compatibility (EMC) have been made. Therefore, it is becoming increasingly important to perform the first EMC design review well before any hardware is available to test.

Abstract In order to model configurations driven by broadband sources (eg, digital signals), it is desirable to employ a full-wave modeling technique that works well at both high and low frequencies. This paper describes a method for improving the low-frequency performance of existing full-wave boundary element techniques and demonstrates how the full-wave model can be used to solve static electric field problems.

Abstract The maximum coupling between printed circuit board components connected to the same power-ground plane pair often occurs at or near power bus resonances. Theoretically, the transfer coefficient, S 21, between two locations on the power bus can be as high as 0dB (ie perfect coupling) near resonant frequencies. However, in practice the coupling is usually much less due to losses in the power bus structure.

Abstract The effect on EMI of stitching multiple ground planes together along the periphery of multi-layer PCB stacks is studied. Power bus noise induced EMI and radiation from the board edges is the major concern herein. The EMI at 3 meters for different via stitch spacing and layer thickness is modeled with FDTD modeling. It is shown that the ground plane stitching effectively reduces the radiated EMI that results from fringing fields at the power bus edges.

Abstract A resistance-inductance-capacitance (RLC) model is described for estimating current waveforms in digital CMOS circuits. The model is based on parameters that are readily derived from information available in board layout files and component data sheets or IBIS (I/O buffer information specification) files.

Abstract Specific design criteria are proposed to mitigate radiated emissions from a resonant enclosure excited by a heat sink acting as a microstrip patch antenna source. In this particular application, the EMI mechanism is assumed to be due to coupling from the dominant TM 010 x mode to one or more resonant modes associated with the enclosure dimensions. The enclosure is then presumed to radiate, at the enclosure resonance frequencies, through one or more apertures, slots, or seams.

Abstract A two-step technique for modeling the radiation from circuit boards with attached cables is developed and applied to various board-cable structures. The technique divides a complex source geometry into two components. One component consists of differential-mode sources and the pieces of the structure that contribute to the differential-mode radiation.

Abstract EMAP5 is a numerical software package designed to model electromagnetic problems. It employs the finite element method (FEM) to analyze three-dimensional volumes, and the method of moments (MOM) to analyze the current distribution on the surface of these volumes. The two methods are coupled through the fields on the dielectric surface. This paper describes the formulation of the EMAP5 code and demonstrates how it can be used to analyze simple printed circuit board configurations

Abstract Noise on the DC power-bus attributed to device switching is among the primary sources of EMI and signal integrity problems. A mixed-potential integral equation formulation with circuit extraction approach is used to model the planar multi-layer power-bus geometry, which can also include arbitrary shaped power regions on multiple layers.

Abstract This paper investigates a canonical printed circuit board (PCB) problem using both a method of moments (MoM) and a partial element equivalent circuit (PEEC) modeling technique. The problem consists of a PCB populated with three traces. One trace is a signal line and the other two are I/O lines that couple to the signal line and extend beyond the boundary of the board.

Abstract An investigation has been undertaken to further study the fundamental mechanisms responsible for inducing high frequency common mode currents on wires attached to multilayer printed wire boards (PWBs). Previous work reported in the EMC literature has demonstrated that the presence of unintended common mode currents on the external cables of electronic equipment is often the primary source of radiated EMI at frequencies above 30 MHz.

Abstract This paper describes the SPICE modeling of printed circuit boards (PCBs) with signal lines and via structures electrically connected to a metal chassis. First, a PCB model is proposed considering the coupling between signal lines and the power bus due to via structures. Next, the model is expanded to include the chassis and grounding posts. The calculated results using SPICE are shown to be consistent with experimental data.

Abstract EMI associated with inter-board connection was studied through common-mode current measurements and FDTD modeling for stacked-card and module-on-backplane configurations. Three types of connections were investigated experimentally including an open pin field connection, an “ideal” semi-rigid coaxial cable connection, and a production connector. Both microstrip and stripline signal routing on the PCB were investigated.

Abstract-The purpose of decoupling capacitors on printed circuit boards is to meet the instantaneous current demands of high-speed active devices while minimizing power bus noise. Embedded capacitance is an alternative to discrete decoupling capacitors and is achieved by taking advantage of the natural capacitance between the power and ground planes. This paper investigates the electrical properties of boards manufactured with four different kinds of embedded capacitance.

I. INTRODUCTION Electronic devices, particularly those that employ digital circuits or work at RF frequencies can be significant sources of unintentional electromagnetic radiation. EMC engineers, who spend a lot of time measuring unintentional electromagnetic emissions from electronic products, generally learn to recognize particular devices or circuit configurations by the electromagnetic “noise” that they generate.