A very low phase noise fully integrated CMOS quadrature LC oscillator for 2.4 GHz bluetooth/WLAN applications

This paper presents a quadrature voltage-controlled oscillator (QVCO) based on the coupling of two LC-tank VCOs. The QVCO could be tuned between 2.41 and 2.64 GHz, and showed a phase noise of -139 dBc/Hz at 1 MHz offset frequency from the carrier across the whole tuning range, for a current consumption of 20 mA with 2.5-V power supply. A figure-of-merit of -190 dBc/Hz is observed.