Research On Linearization Techniques Of Power Amplifier

Linearity of transmits channel is endued with new requirements in the second and the third generation communication system. And power amplifier is the leading factor of the nonlinearity of transmits channel. The linearization of power amplifier has been the hot spot for current mobile communication research. Beasuse of this, this thesis mainly disc- usses the linearization of power amplifier.Based on the comprehensive study of radio power, this dissertation focuses on feed- forward and predistortion, which are most cost effective ways among all linearization technique. This thesis summarizes the domestic and foreign development of linear power amplifier systemically, analyzes the non-linear characteristic of power amplifier,introduces and compares linear technologies used widely, such as feedback, pre-distortion, feed- forward and LINC. In the segment of the linearization of power amplifier, firstly introduces the project about adaptive feed-forward power, gives an adaptivefeed-forward power amplifier scheme,design,simulation and test. The result shows that:The kill of error signal is obvious in adaptive feed-forward power amplifier from test result. Then it also researches the analog predistortion technique and the digital predistortion technique. In the segment of analog predistortion, it introduces some design and research work about third-order distortion generator model, illustrates the feasibility in theory. The analysis of the simulation indicates the design improves intermodulation distortion obviously. The segment of digital predistortion respectively researches the simple model of adaptive pre-distortion based on Look-Up Table and polynomial. The method of steepest descent are applied to update the content in the Look-Up Table. and the nonlinearity of power amplifier is compensated by using polynomial technique. Two predistortion designs show that predistortion technique improves the nonlinearity of the power amplifier, and it is cost effective linearization technique.This article aims to research the main design and simulation of the common linear technologies of power amplifier, and the research shows they have some effect to improve the capability of power amplifier.