A wideband fractional-N frequency synthesizer with novel self-calibration technique

In this paper, a programmable phase-locked-loop (PLL)-based fractional-N frequency synthesizer, with the capacity of automatically adjusting the nominal frequency of voltage-controlled oscillator (VCO) is presented. The monolithic wideband VCO, with digital and analog control, is capable of operating from 1.6GHz to 2.5GHz. Analog control voltage is only varied from 0.8V to 1.2 V to improve the linearity of varactors in submicron process. The synthesizer is, designed in UMC 0.18um RF process, consumes 30.8mW.