Planar Electromagnetic Bandgap Structure for Wideband Switching Noise Mitigation in High Speed Circuits

Abstract

With the increasing demand for modern digital circuit with fast edge rates and high clock frequencies, simultaneous switching noise has become a major concern. When many active devices switch at the same time, the switching noise generated can cause fluctuations or disturbances in the power distribution system (PDS) which, in turn, leads to a degradation of the signal integrity (SI). When this noise propagates along the waveguide like multi-layer printed circuit boards (PCBs), it will be coupled with other vias to affect the functionality of other circuits. This research work is focus on how to mitigate the noise propagation. The problem of SSN has been discussed intensively over the last decade and different approaches have been taken to mitigate it. Typical used methods include the placement of decoupling capacitors, the use of embedded capacitance, via stitching, or a combination of any of these techniques. The most common drawback of previous methods is the limited frequency bandwidth that they can cover (usually below 1GHz). In this study, I proposed using novel planar electromagnetic bandgap (EBG) structure for noise mitigation. I developed novel designs of meander lines EBG structure in combination of super cell concept, and wideband noise mitigation from 250MHz to 12GHz is achieved. Leakage radiation effects from this EBG-patterned surface are also investigated numerically and experimentally. By characterize the radiation effects, especially its near field property, this EBG structures is shown to be a very effective tool for suppressing electromagnetic interference (EMI) from PCBs. A novel concept of using EBG structures as an enhancing shielding technology is introduced. Finally, the effect of these EBG structures on signal integrity (SI) of multi-layer PCBs is characterized using eye diagram. Some potential methods to improve the signal quality of power plane are introduced. Also the potential effect of EBG structure itself on the local switching noise generation is investigated. In summary, this thesis developed a new effective design of planar EBG structure to mitigate noise propagation in power distributed system (PDS). By carefully characterize its EMI and SI performance, we show this planar EBG structure has a potential to be used in next generation IC packaging technology.