High Q-VCO with low phase noise for communications applications

This work describes the design and implementation of a highly integrated, low-noise VCO realized in a 0.35 mum CMOS technology. We focus on the analysis of Q-VCO whose frequence of oscillation is determined by the resonant frequency of LC tank. The Q-VCO phase noise is directly connected to the quality factor of the LC resonant circuit, which is mainly determined by the on-chip inductor in this technology. We can obtain high Q factors over 80 at 2.9 GHz. Even, Q-VCO exhibits lower phase noise performance for a given power dissipation. From a carrier at 2.9 GHz, dissipating 2.4 mA under a 2.5 V power supply and 1V tuning voltage, simulated phase noise results are -1.36 dBc/Hz at an offset of 100 kHz. And -22 dBc/Hz at an offset of 100 MHz