A predistortion linearization system for high power amplifiers with low frequency envelope memory effects

This paper proposes an RF envelope predistortion linearization system that utilizes a combination of an analog envelope predistortion (APD) working in conjunction with a digital look-up table (LUT) based adaptive envelope predistortion (DPD). The APD system is used as an inner loop to correct slowly varying changes in gain, effectively compensating for long time constant memory effects. The DPD forms the outer loop that corrects the distortion over a wide bandwidth. The APD/DPD combination showed up to 6 dB improvement over the DPD alone for a 90W PEP power amplifier.