A wideband LC tank voltage-controlled-oscillator(VCO) is proposed.To solve the impacts of wideband operation on VCO gain(K_(VCO)) variation and start-up constraint,a binary-weighted varactor array and a binary-weighted negative resistance array all with optimal unit values are designed.Implemented in a 0.18μm CMOS process,the proposed VCO shows a frequency tuning range from 1.9 to 3.1 GHz,with a current consumption varying accordingly from 14.2 to 4 mA from a 1.8 V supply.With the proposed K_(VCO) suppression technique,the K_(VCO) varies from 50 to 60 MHz/V in the entire frequency range.The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 3 GHz carrier. A wideband LC tank voltage-controlled-oscillator (VCO) is proposed. To solve the impacts of wideband operation on VCO gain (K_ (VCO)) variation and start-up constraint, a binary-weighted varactor array and a binary- weighted negative resistance array all with optimal unit values ​​are designed. Imposed in a 0.18 μm CMOS process, the proposed VCO shows a frequency tuning range from 1.9 to 3.1 GHz, with a current consumption varying from 14.2 to 4 mA from a 1.8 V supply. the proposed K_ (VCO) suppression technique, the K_ (VCO) varies from 50 to 60 MHz / V in the entire frequency range. The measured phase noise is -117 dBc / Hz at a 1 MHz offset from a 3 GHz carrier.