A 0.5V LC-VCO implemented in 0.18μm CMOS with a novel switched varactor technique is described in this paper. This novel switched varactor technique can increase the varactor control voltage variation range and increase Q of LC tank; also it can reduce phase noise and power consumption of VCO. Forward-body bias technique is used to reduce the threshold voltage and improve gm of transistor. The measured operating current is 4.4mA and the tuning range is 4.6∼5.2GHz. The phase noise is -114dBc/Hz at 1MHz from carrier frequency 4.8GHz.
