A High-Efficiency NRMGC-Based VCO with Enhanced Transconductance and Low Phase Noise

A negative resistance multi-gated circuit (NRMGC) integrated with an NMOS cross-coupled pair is proposed in this design. The topology incorporates four parallel PMOS transistors, with two configured for cross-coupled differential operation and the other two providing a feedback negative resistance. This configuration effectively reduces phase noise from high-order frequency currents through cancellation. The added NMOS cross-coupled pair enhances the transconductance and headroom of the NRMGC, addressing its limited voltage swing. Implemented using TSMC 65 nm LP technology, the proposed VCO achieves a tuning range of 18 GHz to 20.4 GHz. With a high voltage swing and robust startup, the design delivers exceptional phase noise performance at 110.4 dBc/Hz. Furthermore, it boasts an impressive Figure of Merit (FoM) of −190 dBc/Hz and consumes only 4.8 mW of power, highlighting its excellent overall performance.