Design And Implementation Of Broadband Transmitter Linearization Technology

Today is in an era of explosive information,and the amount of information that people communicated has reached an unprecedented level.With the continuous evolution of wireless communication,the amount of information transmitted,including text,voice,video,and the like,is growing.As the amount of data increases,the requirements of communication systems for communication technologies are also increasing.In order to meet these requirements,the academic community has proposed more and more different types of communication systems.However,the modulation methods of different communication systems and the communication bands are different,making it difficult to design broadband wireless transmitters.In order to support broadband and multi-signal communication systems,software radios have emerged.The main idea of software radio is to put communication protocols such as encryption modulation and demodulation on the software side,while other hardware functions only need to build a general hardware platform to complete the design of the whole system.The power amplifier is one of the most power-consuming parts of the communication system.By improving the linearity of the power amplifier and improving the efficiency of the power amplifier,the power consumption in the communication process can be greatly saved.Moreover,it is very meaningful to improve signal quality,communication stability,and utilization of broadband resources.In this thesis,the nonlinear suppression of RF power amplifier in multifrequency multi-mode broadband wireless transmitter in software radio is studied,and the nonlinearity of RF power amplifier is effectively suppressed.Predistortion processing and harmonic elimination processing are performed by intermodulation distortion falling within the frequency band and harmonic distortion falling outside the frequency band,respectively.By constructing a predistortion and harmonic suppression system,the signal can be eliminated from the nonlinear distortion generated after entering the RF power amplifier.Finally,the harmonic suppression memory polynomial is improved,and a simplified generalized memory polynomial model based on generalized memory polynomial is proposed to eliminate harmonics.After Matlab simulation verification,do floating point to fixed point processing.Finally verified on the experimental platform to achieve the desired results.The simulation results show that digital predistortion can reduce ACPR by 22 dB,and the harmonic elimination scheme can also reduce harmonics by about 20 dB.The simulation results show that the proposed scheme can greatly suppress the nonlinearity of RF power amplifier and verify the effectiveness of the proposed scheme.After that,the hardware experiment platform was built,and the actual signal verification showed that the digital pre-distortion technology can reduce the ACPR by about 20 dB.The hardware experiment platform built by Matlab also proves that the proposed harmonic suppression system can reduce the harmonic interference by about 14 dB and achieve the expected goal,which indicates the correctness of the improved harmonic generalized memory polynomial model proposed in this thesis.