A General Adaptive Digital Predistortion Architecture for Stand-Alone RF Power Amplifiers

This paper presents a general architecture of adaptive digital predistorter (DPD) for stand-alone radio frequency (RF) power amplifiers (PAs). The input and output of the proposed architecture are both RF signals, which is compatible with a stand-alone PA. This DPD system consists of three parts: the RF PA for linearization, RF front-ends with two down-conversion paths and one up-conversion path, and a field-programmable gate array (FPGA) board with ADC/DACs. This architecture enjoys the cost and performance advantages of the adaptive digital baseband predistortion while extending the DPD coverage to the general PA applications with direct RF input and output. A DPD prototype for stand-alone PAs is implemented. Performance improvement of the proposed architecture is validated by measurement results on a typical base-station PA. Experimental results demonstrate the generality of the proposed DPD architecture by comparing the performance with the conventional DPD system.