| With the rapid development of the information technique, people has more and more dependence on the computer, at the same time, the user need larger and larger quantity of internected computers and complexity of the types. The traditional wirelined networks can not meet the need because of constriction of design environment, and so on. Therefore, wireless networks appear, which can realize the communication between two or more persons at anytime and anywhere.Due to increasing requirement of digitalization, bandwidth, personalization and mobilization in communication networks, the disadvantage of the traditional transform method has become serious, so OFDM has been in consideration broadly, because of it's advantage of high spectrum efficiency, effective checking multipath interference, lower cost.Now various linearized amplifier techniques are adopted because the signal of OFDM has higher requirement for the linearity of transmitter, and most power amplifiers of transmitter are non-linear such as active biasing, feed-forward, negative feedback, predistortion etc, which can solve the distortion of amplifier well. However, many environment factors including the variation of temperature, main voltage fluctuation, and ageing transmitter affect the stability of the system, thus the technique of the adaptive predistortion becomes very important.In this paper, Linearization of RF power amplifier for OFDM WLAN and the algorithm of adaptive predistortion are mainly researched. Based on the discussion about constitution of RF system and main technique of linearized power amplifier in the system, this paper mainly introduced the requirement of RF system for linearized PA, the PA model and its distortion, the theory and method of predistortion to reduce the distortion of HPA. Presenting an new digital adaptive predistorting design method based on HPA nonlinear fitting. Also the experimental results demonstrated that this method satisfied the requirement of design. |
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