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 −185.1dB 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 (PN), which is essential for narrowing the detected range uncertainty. In this work, a
$\pi $
-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 2.3MHz. At 66.4GHz, the measured PN is −98.2dBc/Hz at 1-MHz offset, and −120.1dBc/Hz at 10-MHz offset.