A comparative study on digital predistortion techniques for Doherty amplifier for LTE applications

This paper investigates and presents comparative performance of three different digital predistortion techniques for GaN-HEMT based Doherty power amplifier (DPA). Look-Up-Table (LUT), Memory polynomial (MP) and Volterra series based (VB) digital predistortion techniques are examined for the linearization of the DPA in LTE uplink applications. Experimental results demonstrate that for the same level of average power in the channel, LUT based DPD approach provides better linearization capability, in terms of both error vector magnitude (EVM) and adjacent channel power ratio (ACPR), with respect to the Memory polynomial and Volterra series based algorithms.