I. Introduction
Wideband suppression of simultaneous switching noise (SSN) in a multi-layer package is in high demand for modern high-speed digital systems. To suppress SSN coupling, electromagnetic bandgap (EBG) structures have been presented in [1]. The EBG structures provide not only wideband suppressions of SSN coupling but also ease of integration into power/ground planes. However, the physical size of previous EBG structures is not applicable to power/ground planes in a package. Minimizing the physical size of an EBG unit cell is of great importance to the suppression of SSN coupling in multi-layer packages using EBG structures.