Periodic structures based on two-dimensional materials: application to phase shifters

A detailed design of a radio-frequency (RF) system that leverages the graphene quantum capacitance for phase shifting is presented. It consists in a periodic replication of a transmission line (TL) loaded with a bias-tunable capacitor (varactor) which is implemented exploiting a state-of-the-art metal-insulator-graphene-metal (MIGM) heterostructure. The resulting distributed system is able to scale the phase shifting (by extending the number of TL+MIGM stages) to the specific targeted application. In particular, for a 10-stage phase shifter (operating at 3 GHz) we predict a phase shift range of ~ 24 degrees in the bias window [−1.5, 0.5] V, with insertion losses of 1.3 dB and return losses of 20.1 dB. The proposed device operates in a reverse configuration, helping the circuit to keep a low dc power consumption (< 10 µW), paving the way to its use in ultra-low-power systems for future ubiquitous flexible electronics.