| With the rapid development of wireless communication, there are more andmore users and the resource of frequency becomes more and more scarcer. To holdmore channels in limited spectrum, it is necessary to use new communication systemsuch as WCDMA, cdma2000 and TD-SCDMA all of which have high spectralefficiency and high chip rate. All of these 3G communication systems have a highercriterion for the linearity of the RF power amplifier. A novel self-adaptive feedforward linearization technology based on DSP ispresented, which is used for WCDMA and 2.1GHz cdma2000 1x basestation. Firstly, both advantages and disadvantages of existing linearization methodswere investigated, especially the feedforward linearization methods. Dual-pilotmethod was used to control the main loop of this new feedforward system. A separateDSP board was designed and implemented to receive the detected data from mainpower amplifier and to process the optimization algorithm and then give out the rightreal-time controlling voltage. Algorithm simulation based on Matlab and systemsimulation based on ADS were both implemented which guaranteed the feasibility ofall the scheme. The TI C5000 series DSP and Maxim A/D and D/A converters wereused to make sure the high precision and high speed. In experimental test, two-tone signal and multi-carrier signal were both used asinput to test the feedforward linearized power amplifier. The IMD3 when usingtwo-tone input and the ACPR when using multi-carrier input were both greatlyimproved. All the results show that this self-adaptive feedforward linearized poweramplifier was effective and practical. The performance of this linearized poweramplifier also meets the requirements of 3GPP.
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