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-F2,3 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 2nd harmonic, which effectively reduces the phase noise and suppresses the flicker noise upconversion within the entire tuning range. The proposed VCO is realized in 40nm CMOS, occupying a core area of 0.375 mm2 and exhibiting an FTR of 41% from 7.8 to 11.9 GHz. The measured best phase noise is -131.9 dBc/Hz at 1 MHz offset, with the corresponding FoM and FoMT are 189.6 and 201.8 dBc/Hz, respectively.