Design of high performance and wide-band VCO with transformer feedback

This paper presents a very low supply voltage, low phase noise and wide tuning range CMOS LC voltage-controlled oscillator with a transformer feedback for a wide-band front-end receiver by a standard 0.18-mum CMOS process. The VCO take an optimum differential transformer to achieve maximize quality factor and minimize the chip area and switching capacitor module are used to maintain a large tuning range. The VCO core power consumption is 6.9 mW from 0.6 V supply and operates with a wide-band from 4.16-5.47 GHz. The measured phase noise is -111.5 dBc/Hz at 1 MHz offset from the carrier frequency at 5.45 GHz.