A wide tuning range high output power 56–74 GHz VCO with on-chip transformer load in SiGe technology

This paper presents a wide tuning range modified Colpitts VCO with high output power. The circuit was fabricated using a lowcost SiGe technology with an ft/fmax of 170/250 GHz. The VCO can be tuned between 56.4 and 73.8 GHz having a tuning range of ≈ 27%. The maximum measured output power is +9.4 dBm, and the output power remains above +7.0 dBm over the entire tuning range. The VCO has a minimum phase noise of -95 dBc/Hz, which stays below -88 dBc/Hz over the entire tuning range. On-chip frequency dividers were used to enable easier measurement. A single transformer was designed and used simultaneously for output matching of the VCO and as an output balun. The overall chip draws 112 mA from a 3.3 V supply, where the VCO draws 45 mA of the total current.