A differentially tuned 1.73GHz-1.99GHz quadrature CMOS VCO for DECT, DCS1800 and GSM900 with a phasenoise over tuning range between -128dBc/Hz and -137dBc/Hz at 600 kHz offset

A fully integrated VCO with quadrature outputs for Zero- or Low-IF DCS1800, DECT or GSM receivers is presented. At 2.5V supply voltage and a power dissipation of 20mW, the VCO features a very low phase noise of -128dBc/Hz or better at 600kHz frequency offset over the tuning range, thus fulfilling more than the tough GSM-specifications. The oscillator is tunable from 1.71GHz to 1.99GHz and has a differential tuning input through a novel combination of NMOS- and PMOS-varactors.