HOW I GET MODEL IN ADS2003 for any undefined amp.

HI I HAVE HXTR3675 ,I WRITE ITS S PAR. NOW I ENTER IT IN ADS2003 TO DEFINE S1P,S2P,MY QUESTION IS HOW I MAKE MODEL TO IT TO SIMULATE IT USING S PAR.SIMULATOR AND CALCULATE NOISE AND GAIN CIRCLES
REGARDS

As I understood...simple.

Place a "2-PORT DATA ITEMS" from scrolling menu on the left that will represent your s-parameter data of your amplifier. Then load your s-parameter data file by browsing in this component by double-click.This data file can be either Touchstone , CITI file or ADS natural data format. After that do your s-parameter simulation.

If you didn't supply Noise Figure , Rn ( or normalized rn ) , you can not do noise figure simulation.

I hope , I haven't misunderstood..

if i understand you have a two port S-parameter file for the device ;
If you have created the file by manually entering the data first make sure it is in a proper format for the simulator to understand; you can look at
attached S2p file for a Siemens transistor for the correct format. the lines marked with "!" are comments and those marked with "#" contain the simulator expressions; the usage of the data item in ADS is already specified above by Bigboss;