Multilayer graphene fundamental wave mixer under DC voltage bias

In this paper, a multilayer graphene mixer with inductor-capacitor resonators (LCR) and microstrip reflector stubs (MRS) loaded with direct-current (DC) voltage bias is presented. As a multifunctional material, multilayer graphene is especially suitable for mixer because of its nonlinearity. The experimental and simulation results show that the effect of bias voltage on multilayer graphene is significant. When the bias voltage is applied, the mixer is converted from subharmonic mixer to fundamental wave mixer. The measured minimum conversion loss with DC-load fundamental wave mixer is 18.9 dB at PLO = 16 dBm, fLO = 800 MHz, pRF = 0 dBm, fRF = 2 GHz which is about 1.2 dB lower than that DC-free subharmonic mixer. In addition, the nonlinear model of graphene is established by simplifying the approximate conductivity.