Single-Input Single-Output Digital Predistortion of Power Amplifier Arrays in Millimeter Wave RF Beamforming Transmitters

In this paper, a theoretical basis for a single-input-single-output (SISO) digital predistorter (DPD) for use in large-scale millimeter-wave (mm-wave) analog/RF beamforming antenna arrays is proposed. The proposed DPD is then validated in measurement by linearizing a 64-element array driven by a 320 MHz wide digitally modulated signal centered at 28 GHz. Measurement results using a block-wise SISO DPD, which uses three sets of SISO DPD model coefficients from training at three different steering angles, achieved a reduction of ACPR to −50 dBc and NMSE to 2.5% across the 120° steering range of the antenna array.