What is Power Added Efficiency?

Power Added Efficiency or PAE of an amplifier is the ratio of effective output power and the DC input power. The effective output power is measured by calculating the difference between the output power and input power. Effective output power = Pout – Pin, where Pout stands for the output power delivered by the amplifier and Pin is the input power that can be handled by the amplifier. This is then divided by the DC power supplied to the amplifier. It is expressed as a percentage value.

The ratio between the output power delivered by the amplifier to the DC input power is called drain efficiency. However, this type of efficiency can be misleading to RF Engineers as it does not consider how much power is utilized by the amplifier. An amplifier can have a high drain efficiency and at the same time have a very low gain. 

Power Added Efficiency is a convenient parameter that is used to determine how much the DC input power contributes to the amplification of an input signal. If an amplifier has an efficiency of 100% this means that all its input power is converted into output power. Practically, such amplifiers don’t exist and a certain amount of DC power is lost in the conversion process as dissipated heat. 

An amplifier can amplify an input signal because of the added power by its DC source. Hence power-added efficiency is preferred mostly over drain efficiency. 

PAE is generally taken into account during the development phase, troubleshooting, quality assurance validation, and production test of integrated circuits (IC’s).

Click here to use the Power Added Efficiency Calculator on everything RF.