A 1.8-GHz CMOS VCO tuned by an accumulation-mode MOS varactor

This work presents a 1.8-GHz VCO tuned by a pMOS capacitor working exclusively in the accumulation and depletion regions. The VCO has been fabricated in a standard 0.6 /spl mu/m CMOS process. It shows a tuning range of about 11% and a phase noise of -137 dBc/Hz at 3 MHz offset from the carrier, for a current consumption of 2.7 mA. The VCO compares favorably with a CMOS VCO tuned by a reverse biased diode varactor.

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