Exploiting Graphene Quantum Capacitance in Subharmonic Parametric Downconversion

This work presents for the first time the unique properties of graphene quantum capacitance (C
_Q
) in parametric circuits. The combination of the C
_Q
and parametric operation results in a distinct topology which enables the realisation of RF powered, receiver and transmitter frontends, with high conversion gain (G
_C
) 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 G
_C
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.