| In order to obtain a larger output power of signal,and improve the efficiency,power amplifier will generally work near the saturation point. This will inevitably lead to serious nonlinear distortion. Digital video broadcasting(DVB)uses lots of modern modulation techniques such as orthogonal frequency division multiplexing(OFDM), Its signal have high peak to average power ratio(PAPR)and wide bandwidth, they are very sensitive to the nonlinear distortion of power amplifier(PA). Nonlinear distortion of RF power amplifier will also make spectrum expansion to original input signal, it will result in adjacent-channel interference and affect others users. In order to solve these problems, power amplifier linearization is an effective way. Based on adaptive digital pre-distortion power amplifier linearization technology has so many advantages such as utility, flexible and cost-moderate, it's a very potential and practical power amplifier linearization techniques which general use in communication industry.This issue is pre-distortion processing for digital TV base-band signal based on FPGA platform, achieving digital television transmitter power amplifier linearization. This platform is a common program for power amplifier linearization. Its biggest advantage is that can adaptive pre-distortion process in parts of digital base-band. The core part of base-band software in FPGA is use digital pre-distortion IP core of Xilinx company. It simplify the process of software development, and improve the efficiency of R&D. Around the IP core, digital pre-distortion base-band process hardware platforms mainly make up of FPGA, DAC and ADC, RF uplink and feedback downlink, it plus the clock board and amplifier board to constitute the entire pre-distortion system. There have high data rates and radio-frequency signals in the whole system, so it have a high requirement to the performance of devices.This paper is based on the above-mentioned hardware platform, arounding debug the digital pre-distortion base-band board and its frequency synthesizer board. The propose was used DPD IP core in FPGA to achieve power amplifier linearization.The main works in this paper was done as follow:1. Introduced the characteristics of digital television as well as their signals.Described the research status and development trend of power amplifier linearization techniques in industry at home and abroad. Described the study purpose and significance of this topic.2. Analyzed the impact of power amplifier nonlinearity to the system . Gave a performance scale indicators for power amplifier. In particular the measured indicators of power amplifier in this topic. It also studied several current prevailing power amplifier linearization techniques. 3. Introduced the hardware platform program of digital pre-distortion based on FPGA. A detailed analysis of the run control flow of MircoBlaze processor in DPD V2.0 IP core was done,and the way of storage distribution in Virtex4 FPGA's SBRAM in this IP core, The purpose was did a better prepare for the application of MircoBlaze processor.4. A detailed debugging of the frequency synthesis program of this issue was done. Introduced all the design application of clock chips in this program. The debugging results are given at last.5. Because of the DVB-T digital base-band signal source which planed to used in the beginning of the program design is not able to achieve in time, and the feedback signal indicators of base-band board hardware platform did not meet the requirements, it could not use the IP core to achieve DPD finally. In such a case, in order to debug the next improving board, the top-level module software application of DPD IP core in FPGA was designed as well as some simulation designed. A detailed hardware debugging was done to the digital pre-distortion base-band board and power amplifier board. After that hardware debugging, the problem-solving methods were put out. Tested the measured results and some debugging maps were put out. |
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