A 2-GHz low-phase-noise integrated LC-VCO set with flicker-noise upconversion minimization

A fully integrated 2-GHz very low-phase-noise LC-tank voltage-controlled oscillator (VCO) set with flicker noise upconversion minimization is presented. Using only integrated planar inductors, the measured phase noise is as low as -125.1 dBc/Hz at 600-kHz offset and -138 dBc/Hz at 3 MHz, The excellent phase-noise performance is achieved by means of an in-house-developed integrated inductor simulator-optimizer, To minimize the upconversion of flicker noise to 1/f(3) phase noise, a flicker-noise upconversion factor is defined, which can easily be extracted from circuit simulation, The technique is applied to demonstrate the relationship between the flicker-noise upconversion and the overdrive level of the oscillators' MOS cross-coupled pair and to develop circuit balancing techniques to even further reduce the flicker-noise upconversion. The 1/f(3) phase-noise corner is minimized to be less than 15 kHz. The VCO's are implemented in a three-metal layer, 0.65-mu m BiCMOS process, using only MOS active devices.