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 vara ctor, respectively. Both VCO's show a lower power consumption and a lower p hase noise than a reference VCO tuned by a more commonly used diode varacto r. The best overall performance is displayed by the accumulation-mode MOS v aractor VCO. The VCO's were implemented in a standard 0.6-mu m CMOS process.