A MM-Wave Frequency doubler based on second harmonic VCO extraction in 40-nm CMOS

This work outlines the design and the performance of a mm-wave push-push cross-coupled voltage- controlled oscillator (VCO) utilizing a frequency doubler in 40nm CMOS technology. The extraction of the second harmonic is performed non-intrusively through the utilization of a transformer from the tail of the fundamental frequency VCO. The primary side serves a dual purpose, functioning both as a filter for the second harmonic and as a balun simultaneously. The circuit employs a MOS varactor along with a four-bit binary weighed capacitor bank to achieve frequency tuning. The integrated VCO spans a broad tuning range of 12.34 GHz, covering frequencies from 52.55 to 64.89 GHz. Simulated phase noise (PN) remains below -97.4 dBc/Hz at a 1 MHz frequency offset within all bands, while power dissipation, including the output stage, is 19.8 mW from a 1.1-Volt supply. Simulated output power consistently exceeds -21 dBm in all frequency bands.