Implementation of Digital Pre-Distortion for power amplifier linearisation in Software Defined Radio

This paper discusses the design and implementation of a Digital Pre-Distortion (DPD) system for RF power amplifier (PA) linearisation in an in-house designed Software Defined Radio (SDR) platform. An indirect learning approach using orthogonal memory polynomial model is adopted for the DPD design. Important aspects of the SDR architecture relevant to DPD implementation are outlined. Several techniques used for efficient real-time implementation are presented. Detailed performance evaluation of the implemented DPD using in-house developed high power amplifiers is also reported. Spectral regrowth suppression of 15dB to 20dB is observed. Memory effect compensation can be inferred from the spectral characteristics of the PA output with and without DPD in the transmit chain.