Digital Predistorter Design Using a Reduced Volterra Model to Linearize GaN RF Power Amplifiers

Abstract

In this paper, a novel method for reducing a Simplified Volterra Series (SVS) model size is proposed for GaN RF Power Amplifier (PA) Digital Predistorter (DPD) design. Using the SVS-modified model, the number of coefficients needed for the PA behavioral modeling and predistortion can be reduced by 60% while maintaining acceptable performances. Simulation and implementation tests are performed for a Class AB GaN PA and Doherty GaN PA using a 20-MHz Long Term Evolution-Advanced (LTE-A) signal. The Adjacent Channel Power Ratio (ACPR) attains-40 dB and-41 dB for the Doherty and Class AB GaN PAs, respectively. The implementation complexity is also studied and the obtained results prove the capability of the proposed model to linearize PA using 3% of the Slice LUTs and 87% of the DSP48E1 available in the Xilinx Zynq-7000 FPGA.

Innovative Technique for HPA Characteristics Extraction and Accurate Predistorsion Function Modeling

“…To determine predistortion and/or HPA transfer characteristics, several techniques are found in the literature, such as look-up tables (LUT) [10][11][12], or various mathematical [13], polynomial with or without memory [14], [15], Volterra [16], Hammerstein and Wiener [17], [18], Neural Networks [19]).…”

Behavioral Modeling of a Multimode Power Amplifier Using Perceptrons with AM-AM and AM-PM Complex-Valued Activation Function

“…The DPD system is designed at baseband level to profit from the benefits of digital signal processing, especially the reduced cost and the capability to generate arbitrary nonlinear mappings with high accuracy [1]. The design of a DPD system requires an accurate and low-complexity nonlinear model for the RF PA [2][3][4]. The choice of the PA behavioral model is a crucial step in the design of a DPD system.…”