Design of GFET-based reconfigurable voltage-controlled amplifiers and analog phase shifters for high-frequency applications

This work presents a reconfigurable radiofrequency (RF) circuit based on a single graphene field-effect transistor (GFET), capable of operating as an analog phase shifter, a voltage-controlled amplifier, or both, while maintaining precise control over gain and phase. The circuit exploits the distinctive properties of graphene, such as its quantum capacitance tunability and ambipolar transport behavior, through a carefully engineered design methodology. A common-source topology is proposed, featuring a simple analog control scheme that enables significant yet accurate gain and phase variations, resulting in a compact, low-power, and highly versatile architecture. The proposed GFET-based designs, operating at 2.4 GHz, achieve a gain variation of 18.3 dB (from -5.79 to 12.51 dB) with a phase accuracy of 1.2 0^∘ when operating as an amplifier, and a phase variation of 22.9 0^∘ with a gain compensation of 2.9 dB when operating as a phase shifter. The evaluation of four distinct circuit configurations further demonstrates the versatility of the proposed approach and its suitability for low-power high-frequency applications, with a power consumption below 30 mW. Overall, the simplicity and performance of this GFET-based architecture highlight the potential of graphene technology for reconfigurable RF circuits, paving the way toward its integration in future ubiquitous wireless systems and beamforming networks.