help for VCO design at 1.575 GHz using ADS simulator

Hello,
I'm going to design a narrow band VCO at 1.575 GHz for a GPS receiver, already i found NE34018 to use it in design. But it dose'nt exisit in ADS library and i dont know how to add it in ADS.

there is a PLL component option in pallete of ADS. there u can find all the components like VCO and all for designing an PLL..!! I couldn t figure out yet how to design a PLL but u can get ur VCO block there ..@@