Tunable IDC Phase Shifter Based on Semiautomated Deposition of Graphene

In this work, a graphene-based tunable phase shifter is proposed which deploys a semiautomated procedure for graphene deposition leading to a high-quality graphene transfer. The deposited graphene's complex impedance values are extracted from measured transmission coefficient values in the X band. Analysis of different widths of graphene is performed for better understanding of the microwave properties of graphene. It is evident that by decreasing the width of graphene, the impedance of graphene decreases, making it more conductive for lower widths. In order to observe the microwave tunable behaviour of graphene, varying DC biasing voltages are applied and the variation of transmission coefficients are measured. From the extracted values of complex impedance of graphene, it is observed that graphene possesses significant reactance variation, something that is not considered in literature. The reactance variation can be exploited in the variation of the phase of microwave signals. The reactance variation of graphene is further enhanced for increased phase variation by deploying it with an Interdigitated Capacitor (IDC). The IDC graphene phase shifter provides a phase variation of 60° with negligible amplitude variation at 9 GHz.