Multiband Electromagnetic-Bandgap Structures for Applications in Small Form-Factor Multichip Module Packages

The design and implementation of package-level electromagnetic-bandgap (EBG) structures is presented. By using spiral-based inductance-enhanced electromagnetic-bandgap structures (IE-EBGs), the relative periodicity for achieving bandgap at extremely low frequencies is substantially reduced in comparison to traditional EBGs. Using both full-wave electromagnetic simulation and experimental characterization, it is demonstrated that this type of structure can exhibit multiple bandgaps, which are individually tunable through variation of the inductance per unit area and/or the unit cell periodicity. Sample structures with dimensions compatible with today´s microprocessor packaging technology are designed and fabricated in a multilayer organic flip-chip ball-grid array package substrate. These package-embedded IE-EBGs have unit cell dimensions less than 750 mum and exhibit the first forbidden bandgaps for electromagnetic wave propagation below 10 GHz, which is a frequency band of interest for commercial wireless communication systems.