An extremely low power 2 GHz CMOS LC VCO for wireless communication applications

An extremely low power low phase noise CMOS LC voltage controlled oscillator (VCO) has been fully integrated in a commercial 0.18 mum CMOS process. To achieve low power and low phase noise, a complementary NMOS and PMOS cross-coupled differential LC structure is used. The LC tank is composed of octagonal-shaped inductors with 2 mum Al metal and standard NMOS varactors. The measured phase noise is -111 dBc/Hz at 1 MHz offset from a 1.87 GHz carrier when the VCO core consumes only a 0.5 mW power from 0.9 V supply. The power consumption of 0.5 mW is the lowest reported in the literature for LC VCOs. This VCO has a figure of merit of -180 dBc/Hz and achieves a 7 % tuning range with a control voltage ranging from 0 ~ 1.4 V, while maintaining a tuning sensitivity of 93 MHz/V over its entire frequency range