Nonlinear Microwave Characterization of CVD Grown Graphene

Abstract

Linear and nonlinear microwave properties of chemical vapor deposition (CVD)-grown graphene are characterized by incorporating a coplanar waveguide (CPW) transmission-line test structure. The intrinsic linear transport properties ( ${S}$ -parameters) of the graphene sample are measured and extracted via a deembedding procedure and then fitted with an equivalent circuit model up to 10 GHz. A statistical uncertainty analysis based on multiple measurements is implemented to estimate the error of the extracted graphene linear parameters as well. Nonlinear properties (second- and third-order harmonics as a function of fundamental input power) of the sample are also measured with a fundamental input signal of 1 GHz. Clear harmonics generated from graphene are observed, while no obvious fundamental power saturation is seen. The measured nonlinearity is applied in a graphene patch antenna case study to understand its influence on potential applications in terms of third-order intermodulation levels.