Identifying Quasi-Identical Power Amplifiers through EVM and NMSE Measurements of Output Data using Digital Post Distortion

Quasi-identical power amplifiers can be differentiated through the unique non-linearities that are inherent to each individual power amplifier (PA). The use of error vector magnitude (EVM) and/or normalized mean squared error (NMSE) metrics relative to the reference input signal has been recently proposed as a metric. In this paper it is experimentally verified that first linearizing the PA outputs using the same digital post distortion (DPoD) technique to correct for the non-linearities of the reference PA, magnifies the differences observed in the EVM and NMSE metrics. As the signal-to-noise ratio (SNR) of the distorted signal output increases, the differences between the EVM/NMSE measurements of the two Pas also increases. At a high enough SNR, two quasi-identical Pas can be reliably differentiated using the EVM/NMSE metrics once DPoD has been applied.