Understanding gain vs Pout plot

Hi All,

I was reading a datasheet and came across to see a plot about Gain vs Pout.Normally we see plot gain vs frequency and pot vs pin to see the behaviour, so why do we need gain vs pout plot and what to understand from it since it is not telling about input power.

http://www.skyworksinc.com/uploads/d...11_203225L.pdf

Gain is Pout/Pin. So it can tell about input power. 1dB compression point is coming from the gain vs. Pin or Pout curves. Where the gain drops, the distortion increases and harmonics appear in the spectrum. I think this is the reason why it is useful.

thanks for the reply, one reason is to tell the amplifier class as well. http://k9la.us/Characterizing_an_RF_..._Pout_Data.pdf
However what i am struggling is to understand is the behaviour for a particular power level.

suppose i am giving pin = -8dbm, now how to tell the gain change between high and low power mode, do i need to do pin = pout - gain just to see for same pin how much output power as changed.

Gain v.s. Pout is for estimation of deviation from linear operation, e.g. BackOff.

Pin has not much meaning in power amplifier, since we can measure only Pout.