Exploiting Graphene Quantum Capacitance in Subharmonic Parametric Downconversion

This work presents for the first time the unique properties of graphene quantum capacitance (CQ) in parametric circuits. The combination of the CQ and parametric operation results in a distinct topology which enables the realisation of RF powered, receiver and transmitter frontends, with high conversion gain (GC) and relaxed local oscillator (LO) requirements. The presented prospect is discussed in details for the down-conversion case. Feasibility of the proposed approach is validated by designing a heterodyne RF receiver frontend centered at 29 GHz. A Verilog-A behavioural model, extracted from S-parameter measurements of a graphene varactor on flexible kapton foil is employed in the verification. Simulation results provide a positive GC of 20 dB and a noise figure (NF) of 4.7 dB without the need for DC bias. The results agree with the presented theoretical analysis of the proposed concept.