This paper presents a millimeter-wave NMOS- PMOS-complementary (CMOS) VCO with a multi-resonant Resistor-Inductor-Capacitor-Mutual Inductance (RLCM) tank. It features an 8-port multi-tap inductor with the switched-capacitor arrays to generate and align the 1st, 2nd and 3rd 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 $_{{@1MHz}}$ down to -111.41 dBc/Hz with a power consumption of 11.1 mW at 1 V; it corresponds to a FOM $_{{@1MHz}}$ up to 189.4 dBc/Hz over a 15.2% tuning range (24.62 to 28.66 GHz), while exhibiting a low 1/f³PN corner between 480 to 730 kHz.