Offset phase-locked loop analysis for millimeter-wave local oscillator source

Phase noise estimation of local oscillators using offset phase-locked loops (OPLL) scheme is one of the primary concerns of low-noise millimeter-wave heterodyne receiver design. In this letter, formulations for phase noise model of voltage controlled oscillator (VCO), external signal noise, mixer, and amplifier were derived. OPLLs for two different type of oscillators, one is a GaAs heterojunction bipolar transistor (HBT) single-varactor-tuning voltage-controlled oscillator and the other is a 13-17 GHz YIG-tuned FET oscillators, were characterized and measured to verify the formulation. The measured phase noise and the calculated results based on the derived linear model are well-matched each other, which indicates that the predicted model provides accurate estimation and fast calculation for the OPLL designs.