There is a growing interest in using CMOS technology in the mm-Wave and terahertz frequency ranges for applications such as spectroscopy, imaging, compact range radars, and remote sensing . Tunable signal sources are one of the main blocks in any such systems. Fundamental frequency voltage-controlled oscillators (VCOs) are widely employed for signal generation. However, CMOS VCOs suffer from low tuning range and low output power due to poor quality fac tor of varactors at high mm-Wave frequencies . To alleviate these drawbacks CMOS frequency multipliers have been proposed for frequencies below 150GHz [2,3]. At higherfrequencies, multipliers are implemented using compound semi conductors [4,5]. In this paper we propose a traveling-wave frequency doubler that operates from 220 to 275GHz in a 65nm CMOS process. Output power of 6.6dBm and conversion loss of 11.4dB are achieved at244GHz.