On the Power and Beam Dependency of Load Modulation in mmWave Active Antenna Arrays
Paper in proceeding, 2020

Linearization of active antenna arrays is gaining increasing interest due to their wide applicability in 5G New Radio (NR) networks. As direct access to the output ports of the power amplifiers (PAs) in highly integrated millimeter-wave (mmW) active arrays is difficult, different over-the-air (OTA) digital predistortion (DPD) solutions have been recently proposed. Large majority of such solutions build on the assumption that the nonlinear behaviors of the parallel PA units are independent of the beam direction. However, in this paper, we show through comprehensive OTA measurements on a commercial 64-element active array operating at 28 GHz, that the nonlinear distortion characteristics and the involved load modulation phenomenon largely depend on the beam direction as well as on the considered transmit power, and also that the beam-dependence increases with increasing transmit power. The findings of the measurements are also connected to the state-of-the-art PA models, paving the way towards the development of more efficient DPD solutions and the associated parameter learning methods for mmW active antenna array transmitters.


Alberto Brihuega

University of Tampere

Matias Turunen

University of Tampere

Lauri Anttila

University of Tampere

Thomas Eriksson

Chalmers, Electrical Engineering, Communication and Antenna Systems, Communication Systems

Mikko Valkama

University of Tampere


2325-0305 (ISSN)

15th European Microwave Integrated Circuits Conference (EuMIC) / 50th European Microwave Conference (EuMC)
Utrecht, Netherlands,

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

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