FPGA-based system for effective IQ imbalance mitigation of RF power amplifiers

Jose Cruz Nuñez Perez, Sergio Alberto Juarez Cazares, Jose Alejandro Galaviz Aguilar, Yuma Sandoval Ibarra, Francisco Javier Perez Pinal, Esteban Tlelo Cuautle

    Research output: Contribution to journalArticle


    To provide an adequate signal integrity to a power amplifier (PA), we propose a digital system for the degradation at the transmitter path, and it is implemented on a field-programmable gate array (FPGA) board. The proposed system offers the following features: A M-ary quadrature amplitude modulation (QAM) digital signal generation and in-phase/quadrature (IQ) imbalance mitigation, and by default, it performs as a predistortion model extraction from PA-measured data. The simulations and tests provided are performed to effectively verify the PA linearity by using 256-QAM signals. The nonlinearities are predicted as a reliable solution for linearizing the PA from measurements of AM/AM and AM/PM conversion curves. The performance is evaluated in terms of linearity, computation complexity, and FPGA hardware synthesis according to a dependability compliance of digital signal processing. Finally, the model is validated with input/output data observations to linearize the model with a fitting normalized mean squared error (NMSE) of around -35 dB, a spurious free dynamic range of 40 dBm, and an adjacent channel power ratio reduction by -20 dBm, for a class-AB broadband radio frequency PA GaN HEMT of 10 W working at 2.34 GHz.

    Original languageEnglish
    JournalInternational Journal of Circuit Theory and Applications
    StateAccepted/In press - 1 Jan 2020



    • digital predistortion
    • FPGA
    • IQ imbalance estimation
    • power amplifiers
    • quadrature modulation
    • RF circuits

    Cite this

    Nuñez Perez, J. C., Juarez Cazares, S. A., Galaviz Aguilar, J. A., Sandoval Ibarra, Y., Perez Pinal, F. J., & Tlelo Cuautle, E. (Accepted/In press). FPGA-based system for effective IQ imbalance mitigation of RF power amplifiers. International Journal of Circuit Theory and Applications. https://doi.org/10.1002/cta.2746