Low power class-C VCO using dynamic body biasing

This article proposes a 3 GHz class-C VCO with dynamic body-biased MOSFET. The dynamic biasing circuit is used to reduce power consumption by switching NMOS from initial class-AB to class-C operation in steady state and this is obtained by switching the body bias of switching transistors to control threshold voltage of switching MOSFET. The dynamic body-biased Class-C VCO is implemented in TSMC 0.18 μm BiCMOS process. The measured phase noise of −119.92dBc/Hz at 1MHz offset frequency from 2.65 GHz carrier while power consuming 2.0mW from a 0.8V supply. Tuning range of VCO is 0.75 GHz, from 2.66 GHz to 3.41 GHz, while the control voltage was tuned from 0V to 2V. The VCO occupies a chip area of 941.22×625.2μm2 and calculated a figure of merit of −185.35 dBc/Hz.