A miniaturized electromagnetic bandgap structure using an inductance-enhanced patch for suppression of parallel plate modes in packages and PCBs

Abstract

In the packages and printed circuit boards (PCBs) of high-speed and mixed-signal electronics, parallel plate waveguides (PPWs) are frequently used as the power/ground plane pair, resulting in a significant problem of electrical switching noise such as simultaneous switching noise and ground bounce noise. This noise inevitably deteriorates system performance. In this paper, we propose an electromagnetic bandgap (EBG) structure using an inductance-enhanced patch (IEP) to suppress PPW modes in high-speed and compact packages and PCBs. The noise suppression characteristics of the proposed IEP-EBG structure were thoroughly analyzed using a dispersion diagram based on a full-wave simulation as well as an equivalent circuit model of a unit cell structure with a Floquet boundary condition. The proposed IEP-EBG structure has the advantages of substantial reductions in the low cut-off frequency of the first stopband as well as unit cell size when compared to a conventional mushroom-type EBG structure without the inductance-enhanced technique. The suppression of the PPW modes of the proposed IEP-EBG structure was verified using measurements of scattering parameters. In the measurements, the low and high cut-off frequencies of the first stopband of the IEP-EBG structure were found to be 1.55 GHz and 2.48 GHz, respectively, while those of the conventional mushroom type EBG structure were 3.52 GHz and 5.3 GHz. For the low cut-off frequency, a 56% reduction was achieved, resulting in substantial miniaturization suitable for compact packages and PCBs.