Design of a 30 GHz rotary traveling wave oscillator with improved frequency tuning range in 0.18 μm CMOS technology

In this paper, the operation of rotary traveling wave oscillators is analyzed, the general oscillation condition is derived, and analytical formula for the oscillator loss is presented. Based on this analysis, switched transmission line is employed to extend the output frequency tuning range. Post-layout simulation shows a frequency tuning range of 3.1 GHz in the vicinity of 30 GHz. The proposed half-quadrature VCO exhibits a phase noise better than −102.2 dBc/Hz at 1 MHz offset frequency. The VCO provides an output power level ranging from −6 to −2.5 dBm with drawing 15.2 mA of dc current from a 1.8 V power supply.