A V-Band CMOS VCO With an Admittance-Transforming Cross-Coupled Pair

A novel circuit topology suitable for the implementation of CMOS voltage-controlled oscillators (VCOs) at millimeter-wave frequencies is presented in this paper. By employing transmission line segments to transform the admittance of the additional cross-coupled pair, the proposed LC-tank VCO can sustain fundamental oscillation at a frequency close to the f_max of the transistors. Using a standard 0.18 mum CMOS process, a V-band VCO is realized for demonstration. The fabricated circuit exhibits a frequency tuning range of 670 MHz in the vicinity of 63 GHz. The measured output power and phase noise at 1 MHz offset are -15 dBm and -89 dBc/Hz, respectively. Operated at a 1.8 V supply voltage, the VCO core and the output buffer consume a total DC current of 55 mA.