A Low-Phase Noise and High Output Swing RF LC-VCO in CMOS Technology

This paper presents the design of a 1.8-V, 3.5GHz CMOS complementary cross-coupled LC-VCO designed for WLAN IEEE 802.11a, two step frequency up-conversion applications with integrated stacked planar inductor. The tuning range of the VCO spans from 3.38 GHz to 3.55 GHz achieved through a depletion mode pMOS based varactor and the corresponding core circuit current consumption is 2.5mA. Implemented in a 0.18mum standard CMOS process the VCO is integrated with a high gain cross-coupled open drain buffer and measures a close in 1/f
³
phase noise of -57 dBc/Hz at 10 kHz of offset frequency. The far out phase noise, 1/f
²
is -116 dBc/Hz at 1 MHz of offset frequency