reduce the bandwidth for the gain

I need a gain from 4-6GHz. Out of the band, I would like to the gain fall down.

But from the simulation, the 2-stages PA has a flat gain at 1-4GHz range.

How can I have a gain like the the bellowing figure? Thanks.

By adding high- and low-pass filters. The shown stop band slope is rather steep, requiring high filter order of 5 to 6.

In top of this, should be mentioned that usually the high pass filter is placed at the input, and the low pass filter should be placed at the output of the amplifier.

Thanks you.

The original input compensation network has one compensation stage. Now I change to two compensation stage, which greatly reduce the low frequency gain.