Are all EGB structures inherently narrowband in operating frequency?
No, this is a common myth. WEMTEC has developed numerous EBG structures for parallel-plate mode suppression which are inherently wideband. For instance, resonant via arrays typically have between one to three octaves of stopband bandwidth. WEMTEC has developed hybrid EBG power planes with more than 30:1 stopband bandwidth, and a bandwidth of more than two decades (100:1) is possible using hybrid EBG structures with conventional low cost chip caps and core materials. • Q: What is the minimum unit cell size for an EBG structure in a PDN? A: The answer is dependent on the type of EBG structure. Hybrid EBG structures can employ chip caps as part of the resonant vias, and this will dramatically lower the cutoff frequency, or the edge of the fundamental stopband, to well below 100 MHz. In fact, hybrid EBG structures with a 30 MHz cutoff and a inch period have been demonstrated in conventional FR4 printed circuit boards.