A 93.9 ? 102.5 GHz Colpitts VCO utilizing magnetic coupling band switching in 65nm CMOS

This paper proposes a modified differential Colpitts CMOS VCO for mm-wave applications requiring wide tuning range, mW output power levels and low DC power consumption. This VCO achieves a large tuning range of 8.6 GHz between 93.9 - 102.5 GHz by using switched magnetic coupling at the gate inductor. Continuous frequency tuning is achieved by controlling the transistor gate capacitance with its bias. The peak output power is -1 dBm at 95.3 GHz without the use of an output buffer and the average phase noise is -90 dBc/Hz at 1 MHz offset (down to -102 dBc/Hz at 97.5 GHz) and -105 dBc/Hz at 10 MHz offset throughout the tuning range. The VCO uses a silicon area of 0.18 mm² including pads and has a DC power consumption of only 5.4 - 21.6 mW resulting in a peak DC-to-RF efficiency of 3.7 %.