psub guard ring design and modeling for the purpose of substrate noise isolation in the SOC era

Abstract

This letter reports the effect of using a p-minus substrate guard ring (psub GR) structure to reduce substrate noise coupling. A corresponding equivalent lump circuit model that predicts the substrate noise isolation behavior of this structure versus distance is also presented. For this particular study, it was found that integrating the psub GR into conventional GR designs can improve substrate noise isolation capabilities of conventional p+ guard rings and n-well guard rings by -15 dB and -5 dB, respectively. This scheme requires no extra masks or processes, and no special substrate material.