Digitally modified filter-less receiver for 2D digital predistortion Of concurrent dual-band power amplifiers

Concurrent dual-band digital predistortion (DPD) is an interesting and popular approach for linearizing power amplifiers (PAs) driven by concurrent dual-band signals in wireless base stations and improving system efficiency. The predistorter kernel extraction requires accurate measurement of the output of PA. In order to observe each band of interest, an RF band-pass filter is placed before the down-converter of each observation receiver. These two filters, centered on each RF band, suppress the concurrent band signal that could fall into the band of interest and corrupt the predistorter extraction process. The use of hardware filter is not preferable in the context of Software Defined Radio (SDR) system which demands flexible topologies with fewer RF components. Therefore, we propose a novel digital modeling based approach to estimate the interfering signal and remove these RF filters. The signal of interest extracted in each band using the proposed method is further used for concurrent dual-band DPD. Performances are reported with an experimental test setup using a 10W power amplifier and 10 MHz LTE and 3-carrier WCDMA signals with 400MHz frequency separation.