A 206 ∼ 220 GHz CMOS VCO using body-bias technique for frequency tuning

A 206 ~ 220 GHz varactor-free voltage-controlled oscillator (VCO) is proposed to improve the output power and tuning range. The topology of the VCO is push-push cross-coupled pair. By using body-bias technique, the parasitic capacitor of the cross-coupled pair can be adjusted, and the varactors in the conventional VCO design can be removed. The proposed VCO was designed and implemented in TSMC 65-nm CMOS technology with a chip size of 0.25 × 0.25 mm². The tuning range is 6.6% (from 206.2 to 220 GHz). The measured phase noise is -66 dBc/Hz at 1 MHz offset frequency. The output power is 1.3 dBm at 216 GHz with 54-mW dc power consumption and its maximum dc-to-RF efficiency is 2.1%. To the best of our knowledge, this varactor-free VCO achieves the highest dc-to-RF efficiency among published CMOS VCOs around 200 GHz.