Distributed MOS varactor biasing for VCO gain equalization in 0.13 /spl mu/m CMOS technology

The paper describes work done on a LC-VCO to linearize its frequency-voltage (Kvco) characteristic in order to extend its versatility. The technology used is a standard 0.13 /spl mu/m CMOS supplied by 1.2 V. The optimization is made on the varactor stage of the resonator and gives a nearly constant Kvco (140/spl plusmn/10 MHz/V from 2.36 GHz to 2.44 GHz), in spite of the MOS varactor non-linear characteristic, with still a good pushing (9 MHz/V) and constant phase noise (-126 dBc/Hz at 3 MHz offset).