Design of Ultra-Low-Power Low Phase Noise CMOS LC-VCO with Transformer Feedback

A fully integrated cross-coupled LC tank voltage-controlled oscillator （LC-VCO） using transformer feed- back is proposed to achieve an ultra-low-power and low phase noise design even at a supply below the threshold voltage. The ultra-low-power VCO is implemented in mixed-signal and RF 1P6M O. 18~m CMOS technology of SMIC. The measured phase noise is - 125.3dBc/Hz at offset frequency 1MHz from the carrier of 2. 433GHz while the VCO core circuit draws only 720txW from a 0.4V supply. The designed VCO can cover the frequency range from 2.28 to 2.48GHz. The tuning range of the circuit is 200MHz（ 8.7% ）, the FOM is - 193.7dB and the output power is about ldBm which is suitable for IEEE 802. 11 b receiver.