This letter presents a highly efficient 60-GHz local oscillator ( LO) in a 90-nm CMOS. The proposed LO consists a 30-GHz LC VCO and a frequency doubler. With this topology, the LO generator has a high output power of -0.1 dBm at 58.2 GHz, consuming only 10.4 mW from a 0.8 V supply, resulting in a record efficiency of 9.4% among ;60-GHz CMOS LOs. At 58.2 GHz, the phase noise is -115 dBc/Hz at a 10-MHz offset. The measured frequency tuning range is from 57.56 to 64.47 GHz. (C) 2016 Wiley Periodicals, Inc