Novel Predistortion Techniques for RF Power Amplifiers

As the mobile phone is an essential accessory for everyone nowadays, predistortion for the RF power amplifiers in mobile phone systems becomes more and more popular. Especially, new predistortions for power amplifiers with both nonlinearities and memory effects interest the researchers. In our thesis, novel predistortion techniques are presented for this purpose. Firstly, we improve the digital injection predistortion in the frequency domain. Secondly, we are the first authors to propose a novel predistortion, which combines digital LUT (Look-up Table) and injection. These techniques are applied to both two-tone tests and 16 QAM (Quadrature Amplitude Modulation) signals. The test power amplifiers vary from class A, inverse class E, to cascaded amplifier systems. Our experiments have demonstrated that these new predistortion techniques can reduce the upper and lower sideband third order intermodulation products in a two-tone test by 60 dB, or suppress the spectral regrowth by 40 dB and reduce the EVM (Error Vector Magnitude) down to 0.7% rms in 16 QAM signals, disregarding whether the tested power amplifiers or cascade amplifier systems exhibit significant nonlinearities and memory effects.