Design of stackup and shorting vias and for reducing edge radiation in multilayer PCB

A practical multilayer printed-circuit-board (PCB) with current excitations is be decomposed into even-mode and odd-mode. The radiation of even-mode exhibits the lower bound of edge radiation and dominates the radiation of system as shorting vias are dense enough. Based on the mode decomposition, the guidelines of stackup for EMI consideration is proposed under practical IO current drawing. After the stackup analysis, some examples with/without shorting via will show the benefit of proposed suggestions. Also, the simulation and design examples will validate the design idea of this paper.