R. De Smedt

Numerical and experimental study of the shielding effectiveness of a metallic enclosure

This paper presents a detailed study of the shielding effectivity properties of metal enclosures. Measurements in anechoic chambers are compared to full-wave electromagnetic simulations. The study is not limited to the frequency range below the first resonance frequency. Different aspects are investigated such as the influence of the size, position and number of apertures, and the effect of the presence of metal plates and of absorbing materials. Where possible, the specific behavior of the shielding effectivity is explained theoretically and existing simple design rules are assessed.

Magnetic polarizability of some small apertures

Curves are given for the dimensionless magnetic polarizabilities \nu_{mx} and \nu_{my} of a few characteristic apertures. The relevant integral equations are solved by the moment method. The subareas are triangular, and the basis functions for the triangles touching an edge take the edge singularity into account. Some data are included for a few typical ring-shaped apertures.

Near-field scanner for the accurate characterization of electromagnetic fields in the close vicinity of electronic devices and systems

A new in-house developed three-dimensional scanning system for measuring electromagnetic fields close to devices and systems is presented. The scanning system is able to perform translations along a three-dimensional Cartesian grid with arbitrary grid size so that any electromagnetic field component can be measured with high accuracy and detail. A near-field scan of an AT motherboard and of a telecom subsystem is described to illustrate the performance of the scanning system. The measurements show that the scanning, system is an excellent diagnostic tool for the detection of EMC problems in an early stage of product development.

Accurate characterization of some radiative EMC phenomena at chip level, using dedicated EMC-testchips

This paper focuses on the radiated EMC-behaviour of ICs and ASICs. An EMC testchip has been developed, encompassing some passive IC interconnection structures. Together with a dedicated EMC-testboard for mounting the IC, as well as a suited EMC measurement set-up, a configuration is obtained that enables one to perform an in-depth evaluation of some important EMC radiating mechanisms at chip level. The EMC-measurements have focused on the comparison between the radiation from IC-interconnects, and the radiation from well-known PCB-interconnects (such as microstrips). From this comparison, the authors observe that an on-chip interconnect may generate significantly more radiation (up to 20 dB for frequencies above 700 MHz) than a microstrip track of comparable length. Especially, packaging effects play a major role in this.

Fast evaluation of the shielding efficiency of rectangular shielding enclosures

In this contribution we evaluate a fast simulation technique to calculate and to characterise the shielding efficiency of rectangular enclosures with apertures. The technique is based on a mode expansion technique developed by Mendez (1970, 1978). The solutions are obtained under a double summation form, achieving an important computational advantage. We compare results of this fast approximative technique with reliable results obtained with a full-wave electromagnetic simulator. It is shown that the mode expansion technique is a far better CAD-tool to evaluate the shielding efficiency of metallic enclosures than existing simple design rules.

Electric singularity near the tip of a sharp cone

The singularity of the electric fields, proportional to the radial coordinate value R/sup nu -1/, is investigated for a very sharp, perfectly conducting cone of arbitrary cross section. It is shown that, in the limit of a very small cone, the exponent nu tends to zero in proportion with the inverse of the logarithm of the maximum opening angle. Results are shown for the circular and elliptic cone, with the flat sector as a special case, and for the pyramid with n equal faces. An expression, valid for arbitrary opening angles, is presented in the case of a flat sector. >

Design and characterization of an active, EMC-dedicated testchip

This paper analyzes the radiated EMC-behaviour of integrated circuits. For this purpose, an active EMC testchip has been designed, focusing on some specific topics such as output driver slew-rate control, on-chip decoupling, ground-bounce reduction, and others. Together with a dedicated EMC-testboard for mounting the chip, as well as a suited EMC measurement set-up, a global configuration is obtained that enables us to perform an in-depth assessment of some important EMC radiating mechanisms at chip level. The first part of this paper describes the design of the EMC-testchip. In the second part, some first EMC-measurements on the testchip are discussed. From this study, it is quantified to what extent output signal staggering and slew-rate control can help in solving EMC-problems at chip-level.

Low frequency scattering through an aperture in a rigid screen—Some numerical results

Abstract The penetration of a plane wave through an aperture in a rigid screen is investigated. The first three terms of the low frequency expansion are evaluated numerically for both simply connected and annular apertures. In the numerical method use is made of a division of the aperture into arbitrary triangles. The singular behaviour at the edges is incorporated in the shape functions, which yields good accuracy and fast convergence. Special attention has been given to the thin ring which can serve as a model for, e.g., imperfectly shielded windows.

A voltage controlled emission model of electromagnetic emission of IC for system analysis

In this contribution, a new modeling methodology for the electromagnetic emissions of integrated circuits for system analysis is presented. The developed models are based on a multipole expansion of the electromagnetic field. Using this macro-representation, the number of necessary model parameters can be drastically reduced. In order to account also for the influence of external circuitry, the models have been appropriately extended towards a voltage controlled emission model. To show the applicability of the new approach, a system-level simulator has been enhanced to use the developed models. The simulation results of a complex configuration are compared to reference calculations. Additionally, the high efficiency of this approach, concerning computation time and memory consumption, is described.

A cooperative research for experimental characterization of signal integrity in deep submicron integrated circuits

The following paper describes a cooperative project between four major European industries and one academic institute, on the development of a novel measurement method for the precise characterization of signal integrity. The method has been implemented in 0.35, 0.25 and 0.18 /spl mu/m CMOS technology, and several aspects of signal integrity have been investigated: interconnect delay, crosstalk within interconnects, delay induced by crosstalk and power supply lines fluctuations. Details on the method and the milestones of the project are reported in the paper.