An Ultra-Low Phase Noise CMOS VCO Design Technique for Mobile Applications

This paper describes an ultra-low phase noise complementary metal-oxide semiconductor (CMOS) voltage-controlled oscillator (VCO) design technique targeted for GSM 900 and DCS 1800 base station (BTS) receiver, which require the toughest phase noise performance between 600 kHz and 3 MHz offset frequency. The proposed VCO suppresses the phase noise by three mechanisms; removes the current source, the main noise contributor in the VCO; includes double tuned resonators to prevent the switching pair from entering the triode region; filters out the second harmonic noise with a small size inductor at the common mode node of the VCO. The feasibility of the proposed VCO is verified using a 65 nm CMOS technology. Operating at around 3.6 GHz frequency range, the VCO is designed to meet the phase noise requirement of micro BTS and normal BTS. The proposed VCO consumes 27 mW dc power from a 0.7 V supply, and achieves the best figure-of-merit of −201dBc/Hz at 3 MHz offset.