Self-IQ-demodulation based compensation scheme of frequency-dependent IQ imbalance for wideband direct-conversion transmitters
Affiliation
Cobham WirelessUniversity of Bedfordshire
Brunel University
University of Warwick
Shanghai Jiao Tong University
Issue Date
2015-09-25Subjects
direct conversion transmittersimage-frequency interference
RF
IQ imbalance
automatic calibration
LO
Metadata
Show full item recordAbstract
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.Citation
Li W, Zhang Y, Huang L, Cosmas J, Maple C, Xiong J (2015) 'Self-IQ-demodulation based compensation scheme of frequency-dependent IQ imbalance for wideband direct-conversion transmitters', IEEE Transactions on Broadcasting, 61 (4), pp.666-673.Additional Links
https://ieeexplore.ieee.org/document/7277012Type
ArticleLanguage
enISSN
0018-9316ae974a485f413a2113503eed53cd6c53
10.1109/TBC.2015.2465138