Linearizing Active Antenna Arrays: Method and Measurements

TL;DR

This paper introduces a new digital predistortion method for linearizing active antenna arrays with diverse nonlinear power amplifiers, validated through extensive over-the-air RF measurements at 28 GHz.

Contribution

A novel framework for efficient DPD-based linearization of active antenna arrays with different nonlinear amplifiers, using a combined feedback signal for observable nonlinear distortion.

Findings

Excellent linearization capabilities demonstrated

Validated with 64-element array at 28 GHz

Efficient implementation in practical systems

Abstract

In this paper, we provide a novel framework for efficient digital predistortion (DPD) based linearization of active antenna arrays with multiple and mutually different nonlinear power amplifiers. The proposed method builds on the use of a combined feedback signal essentially characterizing the observable nonlinear distortion at the receiving end. The proposed method is validated with extensive over-the-air RF measurements on a 64-element active antenna array transmitter operating at 28 GHz carrier frequency and transmitting a 200 MHz wide 5G New Radio (NR) waveform. The obtained results demonstrate the excellent linearization capabilities of the proposed solution, which allows for a very efficient implementation in practical systems.