Integrated 22 GHz low-phase-noise VCO with digital tuning in SiGe BiCMOS technology

A fully integrated voltage-controlled oscillator (VCO) with a 17% tuning range and a low phase noise fabricated in a 0.25 mum SiGe BiCMOS technology is presented. To achieve a wide tuning range while keeping a low gain (K_VCO), the VCO has 16 bands selectable by a 4-bit digital control. Coarse tuning is achieved using MOSFET varactors in a digital manner, which reduces the loss in the resonator. The measured phase noise is -111 dBc/Hz at 1 MHz offset from a 22 GHz carrier. This phase noise level is believed to be the lowest reported so far for an integrated silicon-based VCO in the 20-30 GHz frequency band.