Design And Implementation Of Digital Predistortion System On A Programmable Chip

Power amplifier is an important device in wireless communication system, which is used to magnify the power of the signal. Its working characteristic has a significant effect on the performance of the communication system. Its nonlinear characteristic can cause spectrum extension out of band. In order to reduce the distortion characteristics of the power amplifier, a variety of solutions are put forward. Because of its simple structure and good linear ability, the digital pre-distortion technology is widely used.In this paper, the key technology of digital pre-distortion is analyzed and discussed, a low cost solution of good linear degree is given. This paper uses MicroBlaze on the FPGA chip as the implementation platform for the pre-distortion algorithm, realizing the digital pre-distortion system on a programmable chip. The main contents are as follows.Firstly, this paper discusses the relevant characteristics of the power amplifier and its behavior model, studies the key technologies of digital pre-distortion, determines the overall design of the digital pre-distortion scheme. The digital pre-distortion algorithm parameters are determined by the simulation analysis, and the easy engineering implementation method of indirect inverse matrix is also given. The model parameters of the pre-distortion device and the length of the lookup table are determined by the simulation analysis.Secondly, this paper uses MicroBlaze as the implementation platform for the digital pre-distortion algorithm to implement the overall scheme of the system on a programmable chip. The implementation of the total scheme is given first, the data interaction process of MicroBlaze and FPGA is emphasized. The FPGA implementation of the scheme is given in details. The software work process for completing the pre-distortion parameter calculation is also given in details. The use of FPGA resources is analyzed.Thirdly, this paper completes the testing and analysis for the design scheme. Results show that the designing scheme can perfect the power amplifier output signal to the requirements.This paper realized the digital pre-distortion system on a programmable chip. It can perfect the power amplifier distortion characteristics and lower the implementation cost at the same time. so it has a certain engineering value.