Nonlinear Modeling and Analysis on Concurrent Amplification of Dual-Band Gaussian Signals

Ikuma ANDO  GiaKhanh TRAN  Kiyomichi ARAKI  Takayuki YAMADA  Takana KAHO  Yo YAMAGUCHI  Kazuhiro UEHARA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E96-C   No.10   pp.1254-1262
Publication Date: 2013/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E96.C.1254
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Emerging Technologies and Applications for Microwave and Millimeter-Wave Systems)
Category: 
Keyword: 
nonlinear power amplifier,  spectral regrowth,  ACPR,  EVM,  OFDM,  complex Gaussian distribution,  Flexible Wireless System,  Volterra series expansion,  general Wiener model,  

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Summary: 
In the recently developed Flexible Wireless System (FWS), the same platform needs to deal with different wireless systems. This increases nonlinear distortion in its wideband power amplifier (PA) because the PA needs to concurrently amplify multi-band signals. By taking higher harmonics as well as inter- and cross-modulation distortion into consideration, we have developed a method to analytically evaluate the adjacent channel leakage power ratio (ACPR) and error vector magnitude (EVM) on the basis of the PA's nonlinear characteristics. We devise a novel method for modeling the PA amplifying dual-band signals. The method makes it possible to model it merely by performing a one-tone test, making use of the Volterra series expansion and the general Wiener model. We then use the Mehler formula to derive the closed-form expressions of the PA's output power spectral density (PSD), ACPR, and EVM. The derivations are based on the assumption that the transmitted signals are complex Gaussian distributed in orthogonal frequency division multiplexing (OFDM) transmission systems. We validate the method by comparing measurement and simulation results and confirm it can appropriately predict the ACPR and EVM performance of the nonlinear PA output with OFDM inputs. In short, the method enables correct modeling of a wideband PA that amplifies dual-band signals merely by conducting a one-tone test.