Microwave Pre-distortion Linearization Techniques

With the rapid development of wireless communication, the demand to the frequency resources and the efficiency of power amplifier has become more and more important. The power amplifier is the necessary component in radio frequency system and also a main part of nonlinear products. The linearity of PA has been the most crucial factor to restrict the efficiency of PA, so it has the important actual meanings and the topic of the challenge to linearize the power amplifier. Predistortion is a widely used linearization technique for its unique advantage of easily realization and reasonable cost, and the study of pre-distoring linearizer is becoming one of Most popular research field.The main contents of this tractate is as follows:1. In this paper we discuss the necessity of linearization technique. Than review process history of several linearization system using pre- distortion2. Next we study nonlinear characteristic of microwave PA(power amplifier) system and common mathematic models of PA. Introduce the basic principle of several common linearization technique, including feedback, pre-distortion,feed-forward and LINC. Analyse their applied areas, advantages and shortcomings.3. Last we present two new pre-distortion, a pre-distortion using twice mixing operation and linearizer using anti–parallel Schottky diodes which are directly connected with PA. Besides, we mand a improvemert to the second method. From result simulated by ADS, these two linearizers can effectively restrain nonlinear of PA, improve its linearity; Further more, the linearizers wo improved could not only effectively suppress IMD3, but also IMD5.