Modeling and measurement of simultaneous switching noise coupling and radiation through a cutout and vias in multi-layer packages and PCBs

Abstract

This paper introduces an analytical modeling method for two things; simultaneous switching noise (SSN) coupling through a cutout and vias between the power/ground plane cavities and radiation through a cutout including split in high-speed and high-density multi-layer packages and printed circuit boards (PCBs). Usually, the cutouts are used in multi-layer power/ground plane structures to partition the planes or to separate the planes to isolate simultaneous switching noise (SSN) of noisy digital circuits from sensitive analog circuits or to provide various voltage levels in a power plane layer. The noise-coupling model is expressed in terms of the transfer impedance, which denotes the coupled voltage at a point in a power/ground plane cavity generated by the switching current noise at a point in the other power/ground plane cavity. The proposed modeling and analysis results are compared with measured data up to 10 GHz for the coupling and 3 GHz for the radiation to demonstrate the validity and usefulness of the model and its analysis. Simulation results obtained from the model show acceptable agreement with measurement. Based on the modeling and measurement, it is demonstrated that the cutout is the major gate for the power/ground noise coupling between the plane cavities and that substantial SSN coupling occurs between the plane cavities through the cutout at the resonant frequencies of the plane cavities. The resonant frequencies are determined by shape, material, and size of the partitioned plane cavities. We also analyze and discuss the characteristics of the noise coupling and radiation, which varies with the positions of the cutouts, the noise source in a plane cavity and the observation point. From the analysis, we propose a method of suppression of the power/ground noise coupling between the plane cavities through the cutout. Proper positioning of the cutout and the devices at each plane cavity achieves significant noise suppression at certain resonant f...