Digital Pre-distortion Technology And Its Wcdma Power Amplifier

The linearity and efficiency of the power amplifier are the focus of pow-er amplifier design. In the industry, digital pre-distortion is considered as a p-ower amplifiers linearization direction. Digital baseband pre-distortion (DPD) t-echnology does not include the handling of the RF signal processing, which is the difficult portion. It is only for the LF signal pre-distortion processing, w-hich make its nonlinear characteristics contrary to power amplifier nonlinear c-haracteristics, which compensated to achieve the purpose of power amplifier li-nearization. Combined with modern digital signal processing technology we caneffectively achieve the digital pre-distortion (DPD) function.This paper studies the characteristics of the nonlinear system, learns, and compares the various power amplifier linearization algorithms, select the appro-priate pre-distortion algorithm as the subject algorithm and combine the adapti-ve algorithm based on look-up table, use the digital signal processing technol-ogy, focus on the comparison with traditional DSP processing and realize the DSP-FPGA design flow; digital processing focuses on the process of floating and fixed point processing; using MATLAB Simulink to complete the system'smain function and complex matrix operations. In this paper, a systematic desi-gn(System Generator) is used to complete the system design and implement t-he FPGA-based DSP processing, which greatly simplifies the hardware realizat-ion flow, has greatly shortened the development cycle, which is the applicatio-n of this technology innovation. With WCDMA downlink test signal go throu- gh the digital pre-distortion system, the paper study the corresponding relation-ship between the LUT address and signal amplitude during a software simulat-ion, which brings 15dB to 25dB improvement for the WCDMA adjacent chan-nel power. Tests have shown power amplifier efficiency can also be from 6 % to 34%. Results showed that the DPD system is feasible.First, in terms of DPD hardware implementation of the WCDMA standard RF system, based on the actual requirements of WCDMA transmission system, the paper sets the system bandwidth, frequencies of DUC block and DDC bl-ock, this determined the test program of the digital IF board clock manageme-nt, the VCO frequency of the main channel and detection channel, and the ty-pes of chips, ultimately the paper completed the realization of the digital base-band predistortion system by FPGA. The results show that FPGA-based DSP design represents a significant advantage in terms of resources and the develo-pment cycle.