Today, sub-0.1 V and sub-0.1 mW VCO is not available mainly due to inductor/transistor limitations. Here, the designed 5-GHz VCO using the proposed L/Q-booster demonstrated a PDC of 0.051 mW, and achieved a FoM of 190 dBc/Hz at 0.1 V supply voltage. The VCO can operate even down to 0.05 V under a PDC of 0.036 mW. The proposed booster not only enhances the inductor Q by more than 10×, but also L by 2× to save chip area. As a result, a VCO core area of 0.047 mm² was achieved by using 16-nm CMOS FinFET technology.