ANEWCMOSVCO TOPOLOGY WITHCAPACITIVE DEGENERATIONAND TRANSFORMERFEEDBACK

du.tw. Abstract: Thispaperpresents a new voltage controlled cell. Forsustained oscillations, themagnitude oftheeffective oscillator (VCO)topology forradio frequency operation. The negative resistance IREql hastobesmaller thanRP lowphasenoisedifferential CMOS VCO usescapacitive degeneration andtransformer coupling between thegate and _RonoTik AigeIsn C sourceofthenegative conductance transistor. An on chip r_ transformer inpositive feedback isusedtoincrease the voltage swinginresonator andtoimprove thephase noise. TheVCO istunable from2.85GHzto3.35GHzwith16% I Lp p Cp P C L tuning range, andhasbeenfabricated with0.18umCMOS IP _ _ )I I - technology. Themeasured phase noise at1MHz offset is-119 dBc/Hzattheoperation frequency of3 GHz.Thecircuit draws10mA froma1.8Vsupply. ~~~~~~~by (2), anditshows anegative resistance characteristic.