Crosstalk analysis in graphene multiconductor transmission lines

Abstract

Abstract —The fundamental modes supported by a pair ofidentical graphene nanoribbons in the presence of a groundplane are analyzed. Dispersion, attenuation, and characteristicimpedance of each mode are determined and an equivalent circuitis extracted. An efficient full-wave approach is adopted, basedon a Method-of-Moments discretization of the relevant electric-field integral equation in which the graphene is modeled througha simple local conductivity. A spatial-domain formulation isadopted as it allows for efficiently treating nanoribbons with widetransverse separations and having in mind the future inclusionin the simulation model of the spatial nonuniformity possiblyexhibited by the graphene conductivity. I. I NTRODUCTION Strip transmission lines with submicrometric transverse di-mensions based on graphene (graphene nano-ribbons, GNRs)are emerging as candidates for the realization of future inter-connects in carbon-based nanoelectronic circuits [1], and var-ious approaches have been adopted so far for the assessmentof their propagation features [2]–[7].A Method-of-Moments (MoM) approach is adopted herefor the modal characterization of coupled GNRs, in whichgraphene is modeled through a simple scalar, local conductiv-ity. Whereas non-local effects in GNRs may be non-negligible,especially in the microwave and millimeter-wave frequencyranges [8], a local model may be still adequate in the Terahertzrange and allows for an easy implementation in a spatial-domain MoM code. This approach is much better suited thanits spectral-domain counterpart for studying multiconductortransmission lines with widely separated ribbons; furthermore,a spatial-domain approach is the only possible tool for futuremodeling of spatially nonuniform graphene conductivity.In this paper results are presented, based on such a spatial-domain formulation, for dispersion and attenuation propertiesof the two fundamental (even and odd) modes supported bytwo coupled GNRs.The modal characteristic impedance, calculated adoptinga power-current definition, is also studied; information onpropagation wavenumber and characteristic impedance con-stitutes the basis for future characterizations of graphenemulticondutor lines in network terms [9], [10].Finally, a crosstalk analysis is conducted by means of themodal decomposition method [11] and considering a pair ofnanoribbons above a ground plane.