A　design　of　a　integrated　LC-VCO　which　is　used　in　the　phase-locked　loop　frequency　synthesizer　is　presented.　We　reduce　the　phase　noise　effectively　presupposes　the　tuning　range.　The　VCO　is　realized　by　using　the　technology　of　tsmc　CMOS　0.18um.　The　whole　circuit　is　completed　under　the　environment　of　CANDENCE,　the　result　shows　that　the　phase　noise　is　108dbc/Hz　@100KHz　and　-131.9dbc/Hz@1MHz.　The　working　voltage　is　3V,　and　the　working　current　is　5mA.