Analytical Design of Via Lattice for Ground Planes Noise Suppression and Application on Embedded Planar EBG Structures

Periodic ground via lattice is investigated to suppress the propagation of parallel-plate mode between two ground planes in a multiple layer package or printed circuit board. This parallel-plate mode (or ground/ground mode) plays a main role in the noise coupling or electromagnetic interference of the power planes or signal traces embedded between two ground planes. An analytical solution of the stopband cutoff frequency for designing the ground via pitch and diameter is derived, based on the eigenfunctions expansion method of the cavity model. Using the ground via lattice method and the analytical design solution, coupling noise mitigation and radiation emission reduction of power planes embedded between ground planes are demonstrated numerically and experimentally. Another example is the design of embedded planar electromagnetic bandgap (EBG) structure. The etched power plane of planar EBG structure embedded between the ground planes does not have a bandgap due to the coupling of the ground/ground mode. The minimum ground via number is designed to reproduce the bandgap of the embedded planar EBG structures by using the proposed analytical solution.