A 2.5-GHz eight-phase VCO in SiGe BiCMOS technology

We present a 2.5-GHz voltage-controlled oscillator (VCO) with eight equally distributed phases derived from a 10-GHz LC VCO. Stochastic and static phase errors were obtained by spectrum analyzer measurements in conjunction with an on-chip single-sideband mixer. From the measured phase noise spectrum, we predict an absolute rms jitter contribution of 130 fs in a 2-MHz bandwidth phase-locked loop. A static phase error of less than 0.7° was deduced from the sideband suppression. The eight-phase VCO is tunable from 2.35 to 2.85 GHz and draws 16 mA from a 2.0-V supply. Possible applications include clock and data recovery of a 10-Gb/s signal in a fiber-optic receiver as well as high-precision image rejection receivers and I/Q direct up-converters for radio-frequency applications.