How should be Pin1dB less or more compared with Pout1dB?
Sorry, what? I am not sure I understand the questions. Ideally input/output compression is infinite I guess. And Pout.dB=Pin.dB+Gain.dB . So same is true for input/output compression points.
P1dB(out)=Power Gain+P1dB(in)
Thanks Correct. So our goal should be to increase Power Gain as much as possible, on the hand can I also say that Pin1dB should be as less as possible?
Oh I didn't think in this direction, so ideally there shouldn't be any compression that means Pout and Pin should have linear relation until infinite. In this sense, Pin1dB (Input 1 dB compression Point) should be as high as possible. correct?
In order to hold the amplifier in linear region with lesser harmonics, input power has to be a bit ( 2-4dB) less than P1dB (in).
Increasing of Power Gain has no sense at all, absolute non-linearity is defined by active device itself even the Power Gain is high or low..
I should say I need at least 20 dBm output power at P1dB(out) that means I can have 20 dBm even before reaching P1dB(out).
Of course you need to consider that. Your measurement equipment can only deliver a maximum amount of power without itself compressing. If you do not have enough gain, then you cascade the stages to increase the gain.