HPA need help

I want to design HPA(1GHz to 1.2GHz,P-1>40W).I use the mrf9045,mrf9060 and mrf286,but the result is bad(I found the power gain flatness is very bad,the output P1dB is less 40w from 1GHz to 1.2GHz ).who can tell me the reason.
thanks!

impedence match should be good

Find the optimum load for max output power then match the output to 50 ohms
D.J

MRF9045 is an internal pre-matched transistor designed for 930MHz to 960MHz band.
This is the reason that you get poor gain flatness at 1.2GHz.
It is a chance to improve the gain flatness using multiple poles for the external input and output match.

Good luck