simply , use Sparamter simulation engine in ADS , with it u can get the input impedance of the amp , by ploting S11 on smith chart , and then with the marker go to the frequency u wnat to measure the input impedance in
then take the impedance , and open the smith chart utility in ADS , and then make the load impedance is ur input impedance , then the source is 50 Ohm
and begin to match using L C network , donot forget in smith chart utility to define the frequency to get the correct values of L C
khouly