PA output spectrum with and without LimeADPD

We’re excited to announce that Lime Micro have open sourced their implementation of adaptive digital predistortion (ADPD) for PA linearisation. This can be used with the LimeNET Base Station and other platforms based around the 4x4 MIMO LimeSDR-QPCIe board, to help meet wireless regulatory specifications, while also improving power efficiency and reducing running costs.

The approach taken uses an indirect learning architecture and an algorithm that is based on modelling a nonlinear system by complex valued memory polynomials. Detailed information on the structure and associated equations can be found over on the Myriad-RF wiki. The implementation for LimeSDR-QPCIe is also covered there, along with measured results for two test cases. The source code has also been published to GitHub under the Apache 2.0 licence.

Andrew and the LimeNET Team