6–12 GHz MMIC Double-Balanced Upconversion Mixer based on Graphene Diode

Abstract

In this paper we present the design, fabrication and characterisation of a fully-integrated, wideband double-balanced mixer based on graphene diodes. The circuit is implemented on glass substrate utilising an in-house monolithic microwave integrated circuits (MMIC) process and provides 10 dB conversion loss at 10 GHz with a 3-dB bandwidth of 6 GHz. The measured LO-to-RF isolation is better than 25 dB in the entire band with better than 12 dB return loss at both LO and RF ports in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pmb{50}\ \Omega$</tex> measurement system. To the best knowledge of the authors, the mixer conversion-loss performance outperforms the state-of-the-art graphene-transistor-based mixer circuits.