Adaptive Digital Predistortion Technology For RF Power Amplifiers

Power amplifiers are essential components in communication systems and are inherently nonlinear. The nonlinearity creates spectral growth beyond the signal bandwidth, which interferes with adjacent channels. It also causes distortions within the signal bandwidth, which decreases the bit error rate at the receiver. To improve the power amplifier efficiency without compromising its linearity, power amplifier linearization is essential. Among all linearization techniques, digital predistortion is one of the most cost effective. With the development of the digital technology, digital predistortion technology become to the most potential technology for RF PA linearization. Digital predistortion implementations in the current literature mostly focus on the power amplifier that has a memoryless nonlinearity. As the signal bandwidth gets wider, such as in WCDMA, power amplifiers begin to exhibit memory effects. This is especially true for those high power amplifiers used in wireless base stations. As a result, the current output of the power amplifier depends not only on the current input, but also on past input values. In other words, the power amplifier becomes a nonlinear system with memory. For such a power amplifier, memoryless predistortion can achieve only very limited linearization performance. Therefore, digital predistorters also need to have memory structures.This dissertation investigates robust predistorter models that are capable of...