Backgated Graphene Varactors With Quality Factor-Frequency Product Above 300 GHz

Back-gated, multifinger graphene RF varactors with a de-embedded quality factor frequency product, ${Q} \boldsymbol {\times } {f}$ , above 300 GHz are demonstrated. The effect of different design parameters on the tuning ratio and quality factor at 77 K and room temperature are explored at frequencies between 1 MHz and 18 GHz. The best device has ${Q}$ of 18.4 at 18 GHz. We also perform small signal equivalent circuit modeling on different designs to further explain the effect of design parameters on the RF performance. These results are promising for future integration of graphene varactors in high-speed analog applications.