Communication Rf Power Amplifiers In Digital Pre-distortion Study

Modern wireless communication systems employ spectrally efficient, digitallymodulated signals with bandwiths and time-varying envelopes, and which is very sensitive to power amplifier non-linearity. Amplifier distortion produces a dilation of the spectrum of the input signal ("spectral regrowth") which causes interference to communications in adjacent channels. In addtiion to spectral regrowth, amplifier non-linearities produce in-band distortion which deteriorates the integrity of the transmitted signal and results in high bit error rate (BER) at the receiver end.Linearizeation technology is now widely used in order to reduce the power amplifier nonlinear distortion without loss of efficiency. In all linearization techniques, digital pre-distortion is very effective method. For the power amplifier without memory effect, such as look-up table based predistortion linearizeation can compensate for power amplifier non-linearity and was studied extensively. However, not all power amplifiers can be treated as non-memory effect, especially for broadband applications, such as WCDMA, TD-SCDMA is now widely used in a wide range of communications systems, power amplifier's memory effect can not be ignored. In order to solve the linearity of power amplifier with memory effect, this article uses memory polynomial (MP) digital pre-distortion, MP is a special case of Volterra polynomial, easy to extract pre-distortion parameters and good performance characteristics.In the past 20 years, programmable device technology (FPGA) has been developing rapidly. Fast, high-integration, a large number of support tools and easy using IP core make it preferred choice for a lot of high-speed digital signal processing algorithms.Firstly, the article analyzes the RF power amplifier with memory effect, and then establish RF power amplifier power amplifier memory polynomial pre-distortion models and study of the associated algorithm; finally introduced the FPGA implementation of memory polynomial digital pre-distortion, and then build a complete test environment, and the effectiveness of the predistortion linearizers are demonstrated by experimental results obtained.