| With the rapid development of wireless communication system, the resource of frequency spectrum becomes more and more scarce. For improving the utilization efficiency of spectrum, we need adopt the linearity modulation technology. These complicated modulation ways requires that RF system has fine linearity character, or it will appear inter-modulation distortion and frequency spectrum expansion witch lead to frequency spectrum utilization efficiency coming down. The power amplifier is one of the most important components in RF system and also a main part of nonlinear products. RF systems have a higher criterion for the linearity of the RF power amplifier module. So researching linearization technology of power amplifier become the topic of important actual meaning and the challenge.In this paper we analyze the nonlinear characters of RF power amplifier and introduce the basic principle of feedback, feedforward and pre-distortion technology of linearization. We analyze the feedforward system especially and discuss the scheme of feedforward amplifier in this task. We have designed tradition feedforward amplifier system combined with ADS simulating and have accomplished debugging and testing of the system.In the two-tone test, it shows more than -17dB improvement in the third-order inter-modulation (IM3), offers approximately -46dBc IM3 output when the amplifier's output is 30dBm. It proves the foundation of the theories and a reference price of the project for getting a greater IMD. |
