x band amplifier

I want todesign x band amplifier having gain 12 dB but not finding out the appropriate transistor.Is there any Agilent pHEMT which can be used in order to design the amplifier of required gain and frequency. We have tried many transistor but S21 parameter do not increase above 2 dB at 8 Ghz. Can we place inductor at gate in biasing circuit?it seems to help us.

ATF-36163 has 11dB gain at 12GHz.
http://www.home.agilent.com/USeng/na...886043/pd.html
If you cannot get the spec gain above 8GHz, probably you have a layout or matching problem.
Placing a lumped inductor at the gate (with all parasitics) seems that you have an S11 problem to fix. At these frequencies I would recommend to use only microstrip components.