why power adde efficiency of rf power amplifier decreases when the output power rises

[mohan_ece]

in the design of rf power amplifier,power added efficiency is directly proportional to the ouput power then why power added efficiency decreases when increase in out power magnitude?

 

[johnjoe]

Because with PAE not only the ouput power is considered but also the input power. It means, if you have a quite low gain amplifier, the amplifier is not "producing" the output power. Most of it comes from the input power and PAE drops.

PAE=(Pout-Pin)/Pdc=(Pout-Pout/Gain)/Pdc

Regards

 

[BigBoss]

Because of compression.You see increment in power but it's not linear proportional function of consumed power because of compression.