A Mirror Predistortion linear power amplifier

Abstract

We propose a new type of predistortion linearization technique: “Mirror Predistortion”. In a regular predistortion power amplifier (PA), the AM-AM and AM-PM distortion (Or IMD3, Third Order Inter-modulation Distortion, and IMD5) of the PA are not known before measurement. In the Mirror Predistortion technique, we choose a PA with identical design as, but smaller than the main PA, as a Mirror Predistorter (PD). Since this Mirror PD's nonlinear characteristics tracks the main PA, there is no need for nonlinear characterization for the PD or the PA. We have reduced this concept to practice and have built a mirror predistortion linear PA having 23 dB improvement in IMD3, at a 2-tone total output power of 34 dBm, with 7.5 dB back off from P1dB of 41.5dBm.