Method of Determining Delay Dependence of the Memory Effect in Power Amplifiers and Derivation of Inverse to Cancel the Nonlinear Distortions

Eisuke FUKUDA; Yasuyuki OISHI; Takeshi TAKANO; Daisuke TAKAGO; Yoshimasa DAIDO; Hiroyuki MORIKAWA

doi:10.1587/transfun.E97.A.749

Method of Determining Delay Dependence of the Memory Effect in Power Amplifiers and Derivation of Inverse to Cancel the Nonlinear Distortions

Eisuke FUKUDA, Yasuyuki OISHI, Takeshi TAKANO, Daisuke TAKAGO, Yoshimasa DAIDO, Hiroyuki MORIKAWA

Full Text Views

0

Share
Cite this

Summary :

This paper describes the details of the iteration process used to determine the transfer functions of linear time-invariant (LTI) circuits causing the memory effect of power amplifier (PA). An outline of the method is reported in our work presented at ICCS2012. The accuracy of the method is improved by using cross-correlation spectra at three signal levels, and its validity is confirmed by a computer simulation. The method can be applied to online updating of PAs operating in mobile communication systems. The updating is realized separately from the fast varying nonlinear coefficients. The possibility of updating with a short interval is indirectly shown for the nonlinear coefficients using a procedure similar to that of memoryless PAs. For PAs characterized by the method, this paper also describes the inverses that cancel the nonlinear distortion with minimum complexity. The validity of the inverse is confirmed by a computer simulation on the power spectrum of the PA for orthogonal frequency-division multiplexing (OFDM) signals with 500 subcarriers. The simulated spectra show that the fifth order or higher inverses are effective in keeping adjacent channel leakage power ratio (ACLR) lower than -60dB at the practical signal level. Improvements in the error vector magnitude (EVM) due to the inverse were also confirmed by reductions of gain and phase variations under varying envelope conditions.

Publication: IEICE TRANSACTIONS on Fundamentals Vol.E97-A No.3 pp.749-758

Publication Date: 2014/03/01

Publicized

Online ISSN: 1745-1337

DOI: 10.1587/transfun.E97.A.749

Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)

Category

Authors

Eisuke FUKUDA
  Fujitsu Laboratories Ltd.,The University of Tokyo
Yasuyuki OISHI
  Fujitsu Laboratories Ltd.
Takeshi TAKANO
  Fujitsu Laboratories Ltd.
Daisuke TAKAGO
  Kanazawa Institute of Technology
Yoshimasa DAIDO
  Kanazawa Institute of Technology
Hiroyuki MORIKAWA
  The University of Tokyo

Keyword

power amplifier, IMD, LTI, memory effect, predistortion

Cite this

Copy

Eisuke FUKUDA, Yasuyuki OISHI, Takeshi TAKANO, Daisuke TAKAGO, Yoshimasa DAIDO, Hiroyuki MORIKAWA, "Method of Determining Delay Dependence of the Memory Effect in Power Amplifiers and Derivation of Inverse to Cancel the Nonlinear Distortions" in IEICE TRANSACTIONS on Fundamentals, vol. E97-A, no. 3, pp. 749-758, March 2014, doi: 10.1587/transfun.E97.A.749.
Abstract: This paper describes the details of the iteration process used to determine the transfer functions of linear time-invariant (LTI) circuits causing the memory effect of power amplifier (PA). An outline of the method is reported in our work presented at ICCS2012. The accuracy of the method is improved by using cross-correlation spectra at three signal levels, and its validity is confirmed by a computer simulation. The method can be applied to online updating of PAs operating in mobile communication systems. The updating is realized separately from the fast varying nonlinear coefficients. The possibility of updating with a short interval is indirectly shown for the nonlinear coefficients using a procedure similar to that of memoryless PAs. For PAs characterized by the method, this paper also describes the inverses that cancel the nonlinear distortion with minimum complexity. The validity of the inverse is confirmed by a computer simulation on the power spectrum of the PA for orthogonal frequency-division multiplexing (OFDM) signals with 500 subcarriers. The simulated spectra show that the fifth order or higher inverses are effective in keeping adjacent channel leakage power ratio (ACLR) lower than -60dB at the practical signal level. Improvements in the error vector magnitude (EVM) due to the inverse were also confirmed by reductions of gain and phase variations under varying envelope conditions.
URL: https://globals.ieice.org/en_transactions/fundamentals/10.1587/transfun.E97.A.749/_p

Copy

@ARTICLE{e97-a_3_749,
author={Eisuke FUKUDA, Yasuyuki OISHI, Takeshi TAKANO, Daisuke TAKAGO, Yoshimasa DAIDO, Hiroyuki MORIKAWA, },
journal={IEICE TRANSACTIONS on Fundamentals},
title={Method of Determining Delay Dependence of the Memory Effect in Power Amplifiers and Derivation of Inverse to Cancel the Nonlinear Distortions},
year={2014},
volume={E97-A},
number={3},
pages={749-758},
abstract={This paper describes the details of the iteration process used to determine the transfer functions of linear time-invariant (LTI) circuits causing the memory effect of power amplifier (PA). An outline of the method is reported in our work presented at ICCS2012. The accuracy of the method is improved by using cross-correlation spectra at three signal levels, and its validity is confirmed by a computer simulation. The method can be applied to online updating of PAs operating in mobile communication systems. The updating is realized separately from the fast varying nonlinear coefficients. The possibility of updating with a short interval is indirectly shown for the nonlinear coefficients using a procedure similar to that of memoryless PAs. For PAs characterized by the method, this paper also describes the inverses that cancel the nonlinear distortion with minimum complexity. The validity of the inverse is confirmed by a computer simulation on the power spectrum of the PA for orthogonal frequency-division multiplexing (OFDM) signals with 500 subcarriers. The simulated spectra show that the fifth order or higher inverses are effective in keeping adjacent channel leakage power ratio (ACLR) lower than -60dB at the practical signal level. Improvements in the error vector magnitude (EVM) due to the inverse were also confirmed by reductions of gain and phase variations under varying envelope conditions.},
keywords={},
doi={10.1587/transfun.E97.A.749},
ISSN={1745-1337},
month={March},}

Copy

TY - JOUR
TI - Method of Determining Delay Dependence of the Memory Effect in Power Amplifiers and Derivation of Inverse to Cancel the Nonlinear Distortions
T2 - IEICE TRANSACTIONS on Fundamentals
SP - 749
EP - 758
AU - Eisuke FUKUDA
AU - Yasuyuki OISHI
AU - Takeshi TAKANO
AU - Daisuke TAKAGO
AU - Yoshimasa DAIDO
AU - Hiroyuki MORIKAWA
PY - 2014
DO - 10.1587/transfun.E97.A.749
JO - IEICE TRANSACTIONS on Fundamentals
SN - 1745-1337
VL - E97-A
IS - 3
JA - IEICE TRANSACTIONS on Fundamentals
Y1 - March 2014
AB - This paper describes the details of the iteration process used to determine the transfer functions of linear time-invariant (LTI) circuits causing the memory effect of power amplifier (PA). An outline of the method is reported in our work presented at ICCS2012. The accuracy of the method is improved by using cross-correlation spectra at three signal levels, and its validity is confirmed by a computer simulation. The method can be applied to online updating of PAs operating in mobile communication systems. The updating is realized separately from the fast varying nonlinear coefficients. The possibility of updating with a short interval is indirectly shown for the nonlinear coefficients using a procedure similar to that of memoryless PAs. For PAs characterized by the method, this paper also describes the inverses that cancel the nonlinear distortion with minimum complexity. The validity of the inverse is confirmed by a computer simulation on the power spectrum of the PA for orthogonal frequency-division multiplexing (OFDM) signals with 500 subcarriers. The simulated spectra show that the fifth order or higher inverses are effective in keeping adjacent channel leakage power ratio (ACLR) lower than -60dB at the practical signal level. Improvements in the error vector magnitude (EVM) due to the inverse were also confirmed by reductions of gain and phase variations under varying envelope conditions.
ER -