In third-generation (3G) mobile communication systems, ultralinear amplification is required for complex modulation formats. Nonlinear amplification yields intermodulation distortion (IMD) products and results in unacceptable spectral regrowth in the adjacent channels. To achieve ultralinear amplification, special linearization techniques are usually employed. Various techniques have been developed to reduce IMD products in high-power amplifiers (HPAs), but generally three main linearization methods are used. They are the predistortion method, the feedback method, and the feedforward method.
AR Worldwide Modular RF designs and manufactures HPAs using traditional backoff plus the linearization techniques mentioned above for different applications in the communications and wireless industry. Furthermore, the company has developed a combination of the Doherty technique with analog predistortion techniques in the traditional feedforward method to further improve the goals of high efficiency and high linearity.
Analog Predistortion Technique
It is well known that analog predistortion is a widely used linearization method in power amplifier (PA) designs. AR Worldwide uses this technique in certain applications in order to improve the linearity to a certain level while increasing the efficiency and yet keeping the build costs low.
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Application Note: PA Linearization For Modern Communication Systems