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

Abstract

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -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.