On the Use of MOS Varactors in RF VCO's

This paper presents two 1.8-GHz CMOS voltage-controlled oscillators (VCO's), tuned by an inversion-mode MOS varactor and an accumulation-mode MOS varactor, respectively. Both VCO-s show a lower power consumption and a lower phase noise than a reference VCO tuned by a more commonly used diode varactor. The best overall performance is displayed by the accumulation- mode MOS varactor VCO. The VCO's were implemented in a standard O.6-??m CMOS process.