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 [2–4]. 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
References
[1]
J. Müller and D. Josip, “Integrated capacitor using LTCC,” in Proceedings of the Microtech Conference, Manchester, UK, January 2002.
[2]
B. Mohajer-Iravani and O. M. Ramahi, “Miniaturized wideband plannar electromagnetic bandgap structures using high-k dielectrics,” in Proceedings of the IEEE Antennas and Propagation Society International Symposium, pp. 2921–2924, Honolulu, Hawaii, USA, June 2007.
[3]
B. Mohajer-Iravani and O. M. Ramahi, “EMI suppression in microprocessor packages using miniaturized electromagnetic bandgap structures with high-k dielectrics,” in Proceedings of the IEEE International Symposium on Electromagnetic Compatibility, pp. 1–4, Honolulu, Hawaii, USA, July 2007.
[4]
B. Mohajer-Iravani and O. M. Ramahi, “Suppression of EMI and electromagnetic noise in packages using embedded capacitance and miniaturized electromagnetic bandgap structures with high-k dielectrics,” IEEE Transactions on Advanced Packaging, vol. 30, no. 4, pp. 776–788, 2007.
[5]
B. Mohajer-Iravani and O. M. Ramahi, “Design of EBG structures based on wideband circuit model,” IEEE Transactions on Advanced Packaging, vol. 33, no. 1, pp. 169–179, 2010.
[6]
B. Mohajer-Iravani and O. M. Ramahi, “Radiating emissions from the planar electromagnetic bandgap (EBG) structures,” in Proceedings of the IEEE International Symposium on Electromagnetic Compatibility, pp. 780–783, Fort Lauderdale, Fla, USA, July 2010.
[7]
J. Qin, O. M. Ramahi, and V. Granatstein, “Novel planar electromagnetic bandgap structures for mitigation of switching noise and EMI reduction in high-speed circuits,” IEEE Transactions on Electromagnetic Compatibility, vol. 49, no. 3, pp. 661–669, 2007.
[8]
O. M. Ramahi, V. Subramanian, and B. Archambeault, “Simple and efficient finite-difference frequency-domain algorithm for study and analysis of power plane resonance and simultaneous switching noise in printed circuit boards and chip packages,” IEEE Transactions on Advanced Packaging, vol. 26, no. 2, pp. 191–198, 2003.
[9]
J. Choi, D. G. Kam, D. Chung et al., “Near-field and far-field analyses of alternating impedance electromagnetic bandgap (AI-EBG) structure for mixed-signal applications,” IEEE Transactions on Advanced Packaging, vol. 30, no. 2, pp. 180–190, 2007.
[10]
Y.-W. Huang, T.-K. Wang, and T.-L. Wu, “Design and modelling of miniaturized bandgap structure for wideband GHz-noise suppression based on LTCC technology,” IEEE Transactions on Advanced Packaging, vol. 33, no. 3, pp. 630–638, 2010.
[11]
T.-L. Wu, H.-H. Chuang, and T.-K. Wang, “Overview of power integrity solutions on package and PCB: decoupling and EBG isolation,” IEEE Transactions on Electromagnetic Compatibility, vol. 52, no. 2, pp. 346–356, 2010.
[12]
T.-L. Wu, Y.-H. Lin, T.-K. Wang, C.-C. Wang, and S.-T. Chen, “Electromagnetic bandgap power/ground planes for wideband suppression of ground bounce noise and radiated emission in high-speed circuits,” IEEE Transactions on Microwave Theory and Techniques, vol. 53, no. 9, pp. 2935–2942, 2005.
[13]
B. Mohajer-Iravani, S. Shahparnia, and O. M. Ramahi, “Coupling reduction in enclosures and cavities using electromagnetic band gap structures,” IEEE Transactions on Electromagnetic Compatibility, vol. 48, no. 2, pp. 292–303, 2006.
[14]
R. Remski, “Analysis of photonic bandgap surfaces using Ansoft HFSS,” Microwave Journal, vol. 43, no. 9, pp. 190–198, 2000.
[15]
Ansoft Corporation, “High Frequency Structure Simulator (HFSS),” Pittsburgh, Pa, USA.
[16]
L. Brillouin, Wave Propagation in Periodic Structures: Electric Filters and Crystal Lattices, McGraw-Hill, New York, NY, USA, 1946.
[17]
B. Mohajer-Iravani, Electromagnetic interference reduction using electromagnetic bandgap structures in packages, enclosures, cavities, and antennas [Ph.D. dissertation], Department of Electrical and Computer Engineering, University of Maryland, College Park, Md, USA, 2007.
[18]
D. M. Pozar, Microwave Engineering, Addison-Wesley, Reading, Mass, USA, 1990.
[19]
B. Mohajer-Iravani and O. M. Ramahi, “Reactive power radiated from the planar electromagnetic bandgap structures, a source of EMI in high speed packages,” in Proceedings of the IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, pp. 1840–1843, Spokane, Wash, USA, July 2011.
[20]
C. A. Balanis, Antenna Theory Analysis and Design, John Wiley & Sons, New York, NY, USA, 1997.
