Three-Winding Transformer-Based 60-GHz DCO with -185.1 dB FoM in 40-nm CMOS

This letter presents a 60 GHz fundamental DCO featuring an FoM of –185.1 dB at a 10 MHz offset. The DCO is intended for a 60/120 GHz fundamental-and-harmonic dual-frequency Doppler radar thanks to its cost-efficiency advantages. Based on a three-winding transformer, the proposed class-F DCO achieves good phase noise, which is essential for narrowing the detected range uncertainty. In this work, a π-model of the three-winding transformer is adopted and analyzed. A methodology of optimizing the resonator’s quality factor and the zero-crossing slope is proposed. The DCO is fabricated in 40-nm CMOS and achieves a 14% tuning range with a minimum frequency step of 2.3 MHz. At 66.4 GHz, the measured phase noise is –98.2 dBc/Hz at 1 MHz offset, and –120.1 dBc/Hz at 10 MHz offset.