On the critical issues of DSP/FPGA mixed digital predistorter implementation

This paper describes the hardware platform and the digital signal processing algorithms that form an integrated test bench used for a mixed DSP/FPGA implementation of a digital baseband predistorter for broadband wireless transmitters. In this work, a digital signal processor (DSP) exploits the digital input and output waveforms of the transmitter in order to synthesize the adequate pre-distortion function. This latter, running in real-time on the FPGA, adjusts the baseband signals accordingly in order to insure a transmitter signal output almost free of out-of-band emission along with a low error vector magnitude (EVM). Several critical issues related to the implementation of such digital pre-distorter are reported and discussed.