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Self-IQ-demodulation based compensation scheme of frequency-dependent IQ imbalance for wideband direct-conversion transmitters

  • Wei Li
    ,
  • Yue Zhang
    ,
  • Li-Ke Huang
    ,
  • John Cosmas
    ,
  • Carsten Maple
    ,
  • Jian Xiong
  • Cobham Group
    ,
  • Brunel University London
    ,
  • University of Warwick
    ,
  • Shanghai Jiao Tong University
Research Output: Contribution to journal Article Peer-review

Open access

Abstract

A low cost frequency-dependent (FD) I/Q imbalance self-compensation scheme is investigated in this paper. The direct conversion transmitters are widely used in wireless systems. However, the unwanted image-frequencies and distortions are inevitably introduced into the direct conversion system. This problem is even severer in wideband systems. Therefore, the accurate estimation and compensation of I/Q imbalance is crucial. The current compensation method is based on external instruments or internal feedback path which introduces additional impairments and is expensive. This paper proposes a low cost FD I/Q imbalance self-IQ-demodulation based compensation scheme without using external calibration instruments. First, the impairments of baseband and RF components are investigated. Further, I/Q imbalance model is developed. Then, the proposed two-step self-IQ-demodulation based compensation scheme is investigated. In the first step of the scheme, the local oscillator (LO) related I/Q impairments parameters are estimated. Then in the second step, the overall FD I/Q imbalance parameters are estimated by utilizing the transmitter LO. To realize this self-IQ-demodulation algorithm, this paper introduces minor modifications to the current power detector circuit. Afterwards, the estimated parameters are applied to the baseband equivalent compensator. This sophisticated algorithm guarantees low computation complexity and low cost. The compensation performance is evaluated in laboratory measurement.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 666-673

Journal (Volume, Issue Number)

IEEE Transactions on Broadcasting (Volume 61, Issue 4)

Publication milestones

  • Published - 25/09/2015

Publication status

Published - 25/09/2015

ISSN

0018-9316

External Publication IDs

  • handle.net: 10547/624301
  • Scopus: 84960315280

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