Power Added Efficiency (PAE) Calculator Explained

RF power amplifiers typically have an input, output, and power supply rails. These rails can be either positive, negative, or dual positive and negative voltages. The input, output, and power supply rails all have recommended operating ranges of power, voltage, and current. This range is specified to nominal operation in what the manufacturer was able, or willing to test.

There are occasions where an amplifier may work outside of these specifications. Moreover, given a specific setup, it may be desirable to measure the behavior of an amplifier in-situ. In these cases, using directional couplers at the input/output and current/voltage monitoring sensors, a power amplifier’s behavior can be monitored in real time.

Power Added Efficiency Diagram

Pin is input power, Pout is output power, and Padd is DC supply power.

The Power Added Efficiency (PAE) is a key metric for RF amplifiers, specifically, RF power amplifiers. Using the input power, output power, and supply power (DC input power) it is possible to calculate the PAE. The following simple equation provides PAE as a result:

power added efficiency equation

Efficiency(%) is Power Added Efficiency (PAE), Pout is output power, Pin is input power, and PDC is DC supply power.

From the equation it is clear that PAE metric is simply a ratio of the difference between the input and output power and the DC supply power, or DC input power for the amplifier. This is a useful method of comparing the performance of various power amplifiers using standard approaches. In this way, multiple amplifiers can be tested in real or laboratory conditions and their efficiency can be compared. For broadcast communications and other power or cost constrained applications, PAE is a critical metric, and may even exceed other metric in importance.

Given the value of this metric for RF engineers, Pasternack has provided a free, and registration free, RF power amplifier Power Added Efficiency (PAE) calculator available at this link: https://www.pasternack.com/t-calculator-pae.aspx.

Using the Pasternack Power Added Efficiency Calculator is quick and easy. The user just needs to provide the input power in their chosen units (milliwatts, dBW, dBm, or Watts), output power in chosen units, and DC input power in chosen units. After every input is provided, the calculate button can be clicked and the PAE result is presented. Acceptable PAE results are between 0% and 100% with realizable PAEs between several percent and less than 100% for real amplifiers.

power added efficiency tool