Research And Implementation Of Power Amplifier Digital Predistortion Technology In Zero Intermediate Frequency Communication System

With the increasing demand for high data rate,portability and low power consumption of wireless communication systems,zero-IF technology directly modulates from baseband signals to RF,reducing the complexity,cost and power consumption of the system.More and more research and applications have been obtained.This paper uses the Virtex-6 FPGA-based digital baseband processor of the laboratory proj ect,cascades with the zero-IF transceiver module of the AD9361,and the ARM-based auxiliary control system to form a zero-IF transceiver system for verification and experimentation.And on it to study and implement digital pre-distortion technology.At the same time,the RF power amplifier is an important device that directly affects the performance of the mobile communication device.In order to improve the working efficiency of the power amplifier,it often works in a nonlinear region,which causes distortion of the in-band signal,spectrum broadening of the out-of-band signal,and an increase in the bit error rate.Digital Pre-Distortion technology is a universal and effective method for dealing with the nonlinearity of power amplifiers.It has the characteristics of good linearization and easy engineering implementation.This paper introduces the commonly used nonlinear model of power amplifier,and introduces the classical adaptive model parameter acquisition algorithm.The performance of these algorithms is simulated and compared.Then the widely used predistortion scheme is introduced and analyzed by simulation.The advantages and disadvantages of the scheme,combined with the respective advantages of the look-up table scheme and the polynomial scheme,propose a joint scheme of polynomial/linear adaptive filter which saves storage resources and has better linearization effect,and simulates to verify its effectiveness.Due to the increasing bandwidth of communication systems,traditional digital pre-distortion technology recquires at least five times the bandwidth of the original signal in order to cope with the spectral broadening effect caused by nonlinearity.This will result in high ADC sampling rate requirements and increased costs.At the same time,the sampling rate of the ADC used in the hardware circuit platform is much lower than 5 times of the system bandwidth.In order to linearize the output of the power amplifier of this hardware platform,This paper proposes a band-limited digital predistortion scheme.The simulation and verification of the scheme demonstrate the effectiveness of these narrow-band feedback path digital predistortion systems.