A 2.9-to-7.2GHz Dual-Core Quad-Mode VCO Achieving 206.5dBc/Hz FoMT in 55nm CMOS

This work proposes dual transformer-based resonators for dual-core quad-mode voltage-controlled oscillator (DCQM-VCO), improving the frequency tuning range (FTR) and the phase noise (PN). Specially, our VCO utilizes the frequency gap between the dual modes of the transformer-based resonator, and produces two additional oscillation modes via mode-switching capacitor for FTR extension, while preserving the high tank Q. The wideband VCO is realized in 55nm CMOS, occupying a core area of 0.28 mm² and exhibiting an octave FTR of 84.1% from 2.92 to 7.16 GHz. The measured peak PN is -125.2 dBc/Hz at 1-MHz offset, with the corresponding FoM and FoMT are 188 and 206.5 dBc/Hz, respectively.