An ultra-low power and wide tuning range LC-VCO is presented, where the performances are improved by identifying and avoiding the Q-factor degradation factors in the LC-tank. By the positioning analysis and adoption of MIM capacitor arrays along with minimum size varactors, the proposed VCO with a high-Q inductor, implemented in a 65-nm CMOS technology, operates from 2.35GHz to 2.64GHz (11.7% tuning) with phase noise of −132.92 dBc/Hz at 1MHz offset while dissipating only 72μW from a 0.6-V supply. The FoM of the proposed VCO is 212dBc/Hz and the widest tuning range is shown in the high-Q oscillators.