The Linearization Of RF Amplifier In The Architecture Of Software Radio

By the rapid development of wireless communication the linear modulation methods are widely used. Sinece the envelope of modulated signal fluctuates, these methods generate unwanted intermodulation distortion (IMD) products in a nonlinear Radio Frequency Power Amplifier. So it is necessary to use linearization technique to reduce the adjacent channel interference (ACI). This paper mainly discuss the linearization of RF power amplifier.At first, the nonlinear characteristic of RF power amplification is discussed in this paper, Several typical mathematical model of RF power amplifier is presented in this paper, we analyzed the principle of baseband adaptive predistorter and some typical predistorter architectures; Second introduced several methods of the implementation of adaptive predistorter and compared the polynominal and rational function. Finally, considering the two methods, this paper presents a novel implementation of adaptive predistorter. Through simulation, it is proved that the linearization technique can imporove the linearity of the power amplifier, Aslo a modified version of polymominal predistorter lineariser is presented which has a fast rate of converence by an order of magnitude, Adaptiveity of the proposed lineariser with change in the power amplifer is tested. Results show that the lineariser can adapt to these change.