UC Irvine

A highly efficient push-push voltage-controlled oscillator (VCO) with a new inductive frequency tuning topology for (sub) terahertz frequencies is presented. The tuning technique is based on a variable inductance seen at the emitter node of a base-degenerated transistor. The variable inductor exhibits high quality factor and high tuning range due to the tunable transistor transconductance via bias current. Fabricated in a 0.13-$\mu\hbox{m} $ SiGe BiCMOS process, the VCO achieves a tuning range of 3.5% and an output power of $-$7.2 dBm at 201.5 GHz. The dc power consumption of the VCO is 30 mW, resulting in a high dc to RF power efficiency of 0.6% and a figure of merit $({\rm FoM}-{T})$ of $-$ 165, which is the highest FoM for any silicon-based VCO reported to date at this frequency range. To demonstrate the functionality of the tuning technique, three VCO prototypes at different oscillation frequencies, including one operating in the 222.7-229-GHz range, are implemented and measured. © 1963-2012 IEEE.