Performance Optimization of EBG-Based Common Mode Filters for Signal Integrity Applications

Electromagnetic bandgap structures have been shown to be effective in realizing simple and cheap common mode filters for differential interconnect applications in modern high-speed digital electronics. There are two major advantages offered by this technology. The first is that it relies on the standard planar layout methodology for filter design, applied to either a printed circuit board (PCB) or packaging materials and technology. The second advantage is easy analytical design procedure that requires full wave electromagnetic simulations only at a final stage for the filter geometry refinement to precisely meet given performance specifications. In this chapter, the latter aspect is enhanced by introducing an optimization stage that allows for automated adjustment of geometry parameters of the filter in order to improve its performance in terms of achieving the required central frequency, widening the bandwidth, and increasing the band-notch depth. The optimization approach proposed here combines fast response surface approximation modeling for initial design screening and local derivative-free design improvement using pattern search.