Lower Bound for the Normalized Mean Square Error in Power Amplifier Linearization

The normalized mean square error (NMSE) is a performance criteria commonly used in power amplifier (PA) linearization to quantify the amount of in-band distortion encountered at the output of a PA. This letter presents a closed-form expression for the minimum NMSE that could be obtained in a linearization scenario. The derived expression is verified through numerical simulations and is used to compare the performance of different digital predistortion linearization schemes proposed in the literature.