Low power K-band voltage-controlled oscillator (VCO) using 180nm CMOS technology is presented in this paper. The proposed VCO achieves a wide tuning range from 21.4 to 25.16 GHz by using switched capacitors. The performance of proposed VCO (phase noise, output power and DC power consumption) is improved by designing a new high quality factor inductor that has a shape of figure of eight in 0.18 µm CMOS technology, the quality factor of the proposed inductor is 20.8 at the frequency of interest. Two NMOS switching capacitors to select one of four different frequency. The VCO core consumes 2.7 mA from a power supply of 1.1 V. From the post layout simulation the proposed VCO achieves a wide-frequency tuning range of 21.4 – 25.16 GHz (16.15%), and a good phase noise of − 99 dBc/Hz at 1MHz offset from 25.16 GHz carrier frequency. The calculated figure of merit (FoM) and FoMT of this VCO are-183 dBc/Hz and-187 dBc/Hz.