%0 Journal Article
%T On the Suppression Band and Bandgap of Planar Electromagnetic Bandgap Structures
%A Baharak Mohajer-Iravani
%A Omar M. Ramahi
%J International Journal of Antennas and Propagation
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/164107
%X Electromagnetic bandgap structures are considered a viable solution for the problem of switching noise in printed circuit boards and packages. Less attention, however, has been given to whether or not the introduction of EBGs affects the EMI potential of the circuit to couple unwanted energy to neighboring layers or interconnects. In this paper, we show that the bandgap of EBG structures, as generated using the Brillouin diagram, does not necessarily correspond to the suppression bandwidth typically generated using S-parameters. We show that the reactive near fields radiating from openings within the EBG layers can be substantial and are present in the entire frequency band including propagating and nonpropagating mode regions. These fields decay fast with distance; however, they can couple significant energy to adjacent layers and to signal lines. The findings are validated using full-wave three-dimensional numerical simulation. Based on this work, design guidelines for EBG structures can be drawn to insure not only suppression of switching noise but also minimization of EMI and insuring signal integrity. 1. Introduction The interests to implement electromagnetic bandgap (EBG) structures as a viable solution to reduce electromagnetic interference (EMI) and control switching noise are increasing. However, the size of EBG structures and space restriction on packages pose a challenge. Fortunately, new advanced materials recently produced when combined with EBG structures present possible solutions to the persisting bottlenecks. Amongst newly developed materials are those with very high relative permittivity (above 100). In industrial circles, these materials are typically referred to as high-k materials. In fact, the use of high-k materials in multilayer technologies including printed circuit board (PCB) and low temperature cofired ceramic (LTCC) is becoming popular [1]. In recent work, miniaturized planar EBG structures were designed using high-k materials and were introduced as a highly effective mechanism for suppressing switching noise in high speed integrated printed circuit boards and packages [2¨C4]. The potential and advantages of adapting these new designs were discussed and validated using numerical full-wave three-dimensional electromagnetic simulators. The assessment of attenuation loss between two ports within a board/package parallel layers showed that the EBG patterning of the layer creates a very wide suppression band. However, later studies in [5] showed that the extracted dispersion diagrams for the unit cell of infinite one-dimensional
%U http://www.hindawi.com/journals/ijap/2014/164107/