- Modeling and Digital Predistortion Design of RF Power Amplifier Using Extended Memory Polynomial
- Lee, Young-Sup ; Ku, Hyun-Chul ; Kim, Jeong-Hwi ; Ryoo, Kyoo-Tae ;
- The Journal of Korean Institute of Electromagnetic Engineering and Science, volume 19, issue 11, 2008, Pages 1254~1264
- DOI : 10.5515/KJKIEES.2008.19.11.1254
Abstract
This paper suggests an extended memory polynomial model that improves accuracy in modeling memory effects of RF power amplifiers(PAs), and verifies effectiveness of the suggested method. The extended memory polynomial model includes cross-terms that are products of input terms that have different delay values to improve the limited accuracy of basic memory polynomial model that includes the diagonal terms of Volterra kernels. The complexity of the memoryless model, memory polynomial model, and the suggested model are compared. The extended memory polynomial model is represented with a matrix equation, and the Volterra kernels are extracted using least square method. In addition, the structure of digital predistorter and digital signal processing(DSP) algorithm based on the suggested model and indirect learning method are proposed to implement a digital predistortion linearization. To verify the suggested model, the predicted output of the model is compared with the measured output for a 10W GaN HEMT RF PA and 30 W LDMOS RF PA using 2.3 GHz WiBro input signal, and adjacent-channel power ratio(ACPR) performance with the proposed digital predistortion is measured. The proposed model increases model accuracy for the PAs, and improves the linearization performance by reducing ACPR.