A 7.8-11.9 Ghz Quad-Mode Class-F2,3 VCO with Multi-Stage Cross-Shared Common-Mode Path Achieving -131.9 dBc/Hz 1-MHz Phase Noise and 201.8 dBc/Hz FoMT

This work proposes a quad-mode quad-core class- $\mathrm{F}_{2,3}$ voltage-controlled oscillator (VCO) with multi-stage cross-shared common mode (CM) resonators to achieve low phase noise and high figure of merit (FoM) during wide frequency range. This quad-core VCO is coupled with capacitors and drain-only mode switches to enhance the FTR and reduce the phase noise. Furthermore, four additional CM resonators in cross-shared configuration are introduced to form the multi-stage CM path and create the extended CM response of $2^{\text {nd }}$ harmonic, which effectively reduces the phase noise and suppresses the flicker noise upconversion within the entire tuning range. The proposed VCO is realized in 40 nm CMOS, occupying a core area of $0.375 ~\text{mm}^{2}$ and exhibiting an FTR of 41 % from 7.8 to 11.9 GHz. The measured best phase noise is $-131.9 \text{dBc} / \text{Hz}$ at 1 MHz offset, with the corresponding FoM and FoM ${ }_{\mathrm{T}}$ are 189.6 and $201.8 \text{dBc} / \text{Hz}$, respectively.