Linearizing E- Class Power Amplifier by Using Memoryless Pre-Distortion
thesisposted on 16.01.2020, 19:03 authored by Tunir DeyTunir Dey
Radio Frequency Power Amplifiers (PA) are essential components of wireless systems and nonlinear in a permanent way. So, high efficiency and linearity at a time are imperative for power amplifiers. However, it is hard to obtain because high efficiency Power Amplifiers are nonlinear and linear Power Amplifiers have poor efficiency. To meet both linearity and efficiency, the linearization techniques such as Digital Predistortion (DPD) has arrested the most attention in industrial and academic sectors due to provide a compromising data between efficiency and linearity. This thesis proposed on digital predistortion techniques to control nonlinear distortion in radio frequency transmitters.
By using predistortion technique, both linearity and efficiency can obtain. In this thesis a new generic Saleh model for use in memoryless nonlinear power amplifier (PA) behavioral modelling is used. The results are obtained by simulations through MATLAB and experiments. We explore the baseband 13.56 MHz Power Amplifier input and output relationships and reveal that they apparent differently when the Power Amplifier shows long-term, short-term or memory less effects. We derive a SIMULINK based static DPD design depend on a memory polynomial. A polynomial improves both the non-linearity and memory effects in the Power Amplifier. As PA characteristics differs from time to time and operating conditions, we developed a model to calculate the effectiveness of DPD. We extended our static DPD design model into an adaptive DPD test bench using Indirect Learning Architecture (ILA) to implement adaptive DPD which composed of DPD subsystem and DPD coefficient calculation. By this technique, the output of PA achieves linear, amplitude and phase distortions are eliminated, and spectral regrowth is prevented.
The advanced linearity performance executed through the strategies and methods evolved on this thesis can allow a higher usage of the capability overall performance of existing and emerging exceptionally performance PAs, and therefore an anticipated to have an effect in future wireless communication systems.