Differential- and common-mode radiofrequency interference filters based on complementary split-ring resonators: a conduction and radiation impact analysis

This paper aims to analyse the design techniques of differential transmission lines loaded with metamaterials. Specifically, complementary split-ring resonators (CSRRs) were etched on the ground plane of a microstrip transmission line in order to mitigate both differentialand common-mode propagation in differential signalling. Several prototypes were manufactured and characterised in printed circuit boards (PCBs). The topologies under test were measured and compared as radiofrequency interference (RFI) filters, taking into account frequency response, signal integrity, and nearand far-field radiation impact with regard to a reference (solid ground) board.