Rf Power Amplifier Linearization

With the rapid development of wireless communication the linear modulation methods are widely used. Since the envelope of modulated signal fluctuates, these methods generate unwanted intermodulation distortion (IMD) products in a nonlinear Radio Frequency (RF) Power Amplifer (PA) . So it is necessary to use linearization technique to reduce the adjacent channel interference (ACI). Predistortion is a widely used linearization technique because of its unique advantage of easily realization and reasonable cost,and the research of predistoring linearizer is becoming the hot research field. The principle of power amplifier is introduced at first in this paper, The nonlinear influence, such as AM/AM and AM/PM conversion, has also been analyzed in this paper. Some common linearization techniques, such as feedback, feed-forward and pre-distortion, have been introduced and predistortion has been especially described. At last, the scheme of subject and the principle of this linearizer is represented and analyzed in detail, and the results for the amplifier with and without linearizer are given. The results show that distortion reduction could be achieved.