A comparative study of CMOS LC VCO topologies for wide-band multi-standard transceivers

In this paper a comparison between two widely used VCO topologies, in standard 0.35 /spl mu/m CMOS technology is presented. The VCOs, based on an NMOS and a complementary structure, are designed to operate in a wide band frequency range suited for future multi-standard WLAN radios. The comparisons are carried out from the perspectives of tuning range, power dissipation and phase noise. The results, which are based on simulations, show that both circuits are applicable for the targeted operation band of 4.5-6.5 GHz, while the complementary VCO shows less power consumption and lower phase noise levels.