This paper presents an adaptive body-biased lowvoltage VCO. Despite the 0.5-V supply, the VCO uses coarse digital tuning by employing voltage-boosting technique. In addition, the effect of PVT variations is reduced by adaptive bodybiasing technique. The proposed VCO is implemented in 0.18 μm CMOS technology and operates at 2.4 GHz. It achieves phase noise of -115.8 dBc/Hz at 1-MHz offset and 7.3 % of tuning range, while consuming 200 μW. Figure-of-merit with the tuning range is -189.1 dBc/Hz, which is the lowest among the recent state-of-the-art low-voltage VCOs.