This paper investigates the errors that can result when applying two d
ifferent definitions of power-added efficiency to RF power amplifiers.
The first definition is generic to all multiple-port networks and is
simply the ratio of the total output power to total input power. The s
econd definition is specific to RF power amplifiers and widely regarde
d as the industry standard. It has been found that, for power amplifie
r applications, the error can be highly significant.