A Millimeter-Wave CMOS VCO Featuring a Mode-Ambiguity-Aware Multi-Resonant-RLCM Tank
Hao Guo, Yong Chen, Chao-Wei Yang, Pui‐In Mak, Rui P. Martins
Abstract
This paper presents a millimeter-wave NMOS-PMOS-complementary (CMOS) VCO with a multi-resonant <i>Resistor-Inductor-Capacitor-Mutual Inductance</i> (RLCM) tank. It features an 8-port multi-tap inductor with the switched-capacitor arrays to generate and align the 1<inline-formula> <tex-math notation="LaTeX">$^{{\text {st}}}$ </tex-math></inline-formula>, 2<inline-formula> <tex-math notation="LaTeX">$^{{\text {nd}}}$ </tex-math></inline-formula> and 3<inline-formula> <tex-math notation="LaTeX">$^{{\text {rd}}}$ </tex-math></inline-formula> harmonic resonances; all exhibit high impedance and high intrinsic quality factor to improve the absolute phase noise (PN) at both the flicker and thermal regions. The inductor of the RLCM tank introduces a metal resistor technique to fully prevent the mode-ambiguity issue during the VCO startup. Meanwhile, we first propose a detailed analysis of the upper and lower bound of the metal resistor, which is verified by the theoretical analysis, and circuit simulation. Prototyped in 65-nm CMOS technology, the VCO scores a PN<sub>@1MHz</sub> down to −111.41 dBc/Hz with a power consumption of 11.1 mW at 1 V; it corresponds to a FOM<sub>@1MHz</sub> up to 189.4 dBc/Hz over a 15.2% tuning range (24.62 to 28.66 GHz), while exhibiting a low 1/<inline-formula> <tex-math notation="LaTeX">$\text{f}^{3}$ </tex-math></inline-formula>PN corner between 480 to 730 kHz.