Design and realization of an ultra-low-power low-phase-noise CMOS LC-VCO

A fully integrated cross-coupled LC tank voltage-controlled oscillator（LC-VCO） using transformer feedback is proposed to achieve a low phase noise and ultra-low-power design even at a supply below the threshold voltage. The ultra-low-power VCO is implemented in the mixed-signal and RF 1P6M 0.18-μm CMOS technology of SMIC. The measured phase noise is-125.3 dBc/Hz at an offset frequency of 1 MHz from a carrier of 2.433 GHz,while the VCO core circuit draws only 640μW from a 0.4-V supply.The designed VCO can cover a frequency range from 2.28 to 2.48 GHz.The tuning range of the circuit is 200 MHz（8.7%） and the FOM is-195.7 dB,which is suitable for an IEEE 802.11b receiver.