Research On Key Technology Of Predistortion Of High Efficiency Power Amplifier

With the rapid development of modern wireless communication systems,variousnon-constant envelope modulation schemes and multi-carrier techniques are widelyapplied.These modulation signals posses the characteristics of high spectral efficiency,high peak to average power ratio (PAPR) and wide band.The RF power amplifier hasmemory and nonlinear characteristics,after the signal amplified by RF power amplifierwill produce nonlinear distortion,manifest as in-band distortion and out-of-bandspectrum extention. In order to ensure the amplified signal accurately, RF poweramplifier needs to back-off to work in the linear region.However,back-off work willreduce its efficiency.The RF power amplifier adopted back-off to increase linearity isjust10%efficiency.There are many kinds of RF power amplifier linearization techniques are putforward to overcome the contradiction between linearity and efficiency.Because of thehighly digitalization,flexible algorithm,reliable performance,many researchers choosedigital predistortion to realize its linearization.First of all,this article reviews the development process of the power amplifierlinearization techniques and compares the advantages and disadvantages of theselinearization techniques.Then we study the nonlinear characteristic and memory effectof power amplifier,and its influence on the system,analyses and compares the variousmodels of power amplifier on the base of before study.Secondly,in this article,we explore and research the key technology of digitalpredistortion,the characteristic and model of RF power amplifier, analyze and simulatethe key technology of digital predistortion,determine the algorithm and memorypolynomial model of digital predistortion.Then, on the basic of above analysis,realizethe digital predistortion algorithm on a hardware platform.Finally,build the digital predistortion algorithm testing platform to test andanalyze its performance. The results show the signal processed by digital predistortionhas more than20dB improvement, the ACLR of left adjacent channel is-46.8dBc,theright adjacent channel is-47.4dBc.The efficiency of power amplifier is up to41%. These results prove that the digital predistortion technology can effectivelyimprove the RF power amplifier’s linearity, and has a very good feasibility. It ismeaningful to develop and research high efficiency power amplifier and valuable toaccelerate its commercial application of next generation base station.