A predistortion correction method for quadrature modulation amplitude and phase imbalance of SAR excitation signal

doi:10.7523/j.ucas.2022.079

Abstract

Abstract: Analog I/Q modulation technology is one of the most commonly used and important technical means in broadband synthetic aperture radar (SAR) exciter design. With the increasing instantaneous bandwidth of radar system, the amplitude-phase consistency of analog I/Q modulation can not be completely guaranteed by the symmetrical characteristics of devices, and the spurious distortion caused by the IQ imbalance in broadband radar transmission system will deteriorate progressively. This paper proposes a digital predistortion method which can extract all amplitude-phase errors on the whole transmission channel， mainly including IQ imbalance， by modeling the system error and building a test system, map the amplitude-phase errors to the IQ branch of digital baseband signal output, and compensate the amplitude-phase distortion of the transmission channel. Finally, combined with the actual radar transmitting system, the distortion of the whole transmitting link is corrected by using the predistortion method. The test results before and after correction are given， demonstrating the effectiveness of the method.

Key words: SAR, I/Q modulation, wideband, IQ imbalance, amplitude-phase errors

CLC Number:

TN958

JIA Yingxin, WANG Yanfei. A predistortion correction method for quadrature modulation amplitude and phase imbalance of SAR excitation signal[J]. Journal of University of Chinese Academy of Sciences, 2024, 41(4): 524-532.

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