A power-optimized CMOS LC VCO with wide tuning range in 0.5-V supply

A power-optimized low-voltage VCO with wide tuning range is proposed. The VCO achieves low power by optimum selection of inductance in the L-C tank. Despite the low power supply near threshold voltage, the VCO achieves wide tuning range by using a voltage-boosted digital tuning technique. It is shown that the power consumption of VCO with a required output swing and phase noise can be minimized if the inductance is chosen such that it's LQ and Q/L is maximized. To increase the tuning range, a digital tuning method is used where the output voltage of the VCO is exploited to generate a high voltage for the switches in the digital tuning scheme. The proposed VCO achieves phase noise of -120 dBc/Hz at 1-MHz offset and 18 % tuning range while consuming 660 /spl mu/A in 0.5-V supply. Figure-of-merit with tuning range of the proposed VCO is -197.1 dB, which is the lowest among the recent state-of-the-art low-voltage VCOs.