Power-added efficiency
Power-added efficiency (PAE) is a metric for rating the efficiency of a power amplifier that takes into account the effect of the gain of the amplifier. It is calculated (in percent) as: P A E = 100 × P O U T R F − P I N R F P I N D C {\displaystyle \mathrm {PAE} =100\times {\frac {P_{OUT}^{RF}-P_{IN}^{RF}}{P_{IN}^{DC}}}} It differs from most power efficiency descriptions calculated (in percent) as: η = 100 × P O U T R F / P I N D C {\displaystyle \eta =100\times {P_{OUT}^{RF}}/{P_{IN}^{DC}}} PAE will be very similar to efficiency when the gain of the RF power amplifier is sufficiently high such that a low RF input power causes the RF power amplifier output to reach a certain level.