Sub- THz Switch-less Reconfigurable Triple-/Push-push Dual-band VCO for 6G Communication

This work presents a novel switch-less reconfigurable triple-/push-push dual-band VCO topology and design methods for a W-band metal-oxide-semiconductor (CMOS) voltage-controlled oscillator (VCO). A clover-shaped inductor with a three-port connection and single frequency multiplied output port configuration provides switch-less mode changes between triple-push and push-push operation. This topology is demonstrated in a W-band VCO by controlling three cores with a measured phase noise of −109.17 dBc/Hz at a 10-MHz offset of a 105.3 GHz carrier. The measured center frequency of each band is 91.04 GHz and 102.33 GHz with a tuning range of 10.4% and 14.1 %, respectively. The proposed VCO with independent core on/off state control enables low parasitic switch-less frequency band shift resulting in a superior tuning range compared to those of conventional dual-/single-band VCOs. The effectiveness of this approach is demonstrated through fabrication in a 28-nm CMOS process, with the best FOMT being −174.4 dBc/Hz in this case.