A Dual-Core 8-17 GHz LC VCO with Enhanced Tuning Switch-less Tertiary Winding and 208.8 dBc/Hz Peak FoMT in 22nm FDSOI

This work presents a low phase noise wide tuning range dual-core transformer-based VCO using a switch-less tertiary magnetic coupling loop. The design employs the benefits of transformer-switching without incurring switch loss and quality factor degradation, and also the benefits of mode-switching without the parasitics from the mode-selection network. The VCO uses dual-mode operation with a constant quality factor capacitors bank and a positive feedback DC-coupled inductive-degenerated output buffer to maximize the tuning range. The VCO, implemented in 22nm FDSOI, achieves a 72% tuning at 8-17 GHz and a figure-of-merit-tuning (FoM_T ) of 208.8 dBc/Hz at 11 GHz. The chip operates from an 0.45 V supply with a power consumption of 17-33 mW and a core area of 0.39 mm². To the authors knowledge, the VCO achieves the highest FoM_T and lowest supply for designs over 10 GHz.