Nonlinear modeling and digital predistortion for HF transmitters with harmonic cancelation

Abstract

High frequency (HF) transmitters implemented with the multi-octave power amplifier (PA) are always faced with the problem of interfering harmonics because of the nonlinearity of the PA. In this paper, the harmonic cancelation digital predistortion (HC-DPD) scheme is proposed and well discussed to cancel the in-band intermodulation distortion (IMD) as well as out-of-band harmonics at the same time. With the digital filter-less scheme, the bulky and lossy filter banks can be removed. Nonlinear models are first utilized to approximate the nonlinear behavior of the HF PA and compared in terms of the model accuracy. Then, the learning architecture, model identification, and feedback compensation of the HC-DPD scheme are detailed discussed. Finally, a series of simulations and experiments demonstrated the effectiveness of the proposed nonlinear models and linearization algorithms.

A Digitally assisted nonlinearity suppression architecture using over‐the‐air beam cancelation

“…The power amplifier (PA) is a crucial and energy‐intensive constituent of the RF chain 2 . A PA typically operates with a nonlinear dynamic range, resulting in in‐band and out‐of‐band nonlinear distortion.…”

“…The power amplifier (PA) is a crucial and energy-intensive constituent of the RF chain. 2 A PA typically operates with a nonlinear dynamic range, resulting in in-band and out-of-band nonlinear distortion. The in-band distortion reduces the error vector magnitude (EVM) and degrades the link performance, while the out-of-band distortion breaks the spectral masks and interferes with other users of adjacent channels.…”