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High frequency (HF) transmitter implemented with the multioctave broadband power amplifier (PA) is always faced with the problem of interfering harmonics because of the nonlinearity of the PA. With the harmonic‐cancelation digital predistortion (HC‐DPD) scheme, the harmonics at lower frequencies can be canceled by the injected components and the harmonics at higher frequencies can be filtered out using a low‐pass filter (LPF). However, the HC‐DPD scheme brings the problem of unwanted spurs while lowering the requirements for sampling rate. In this article, a time‐delay neural network (TDNN) model is used to replace the conventional memory polynomial (MP) model in the forward modeling. Theoretical derivation and simulation results validate the effectiveness of the TDNN model in harmonic cancelation and spur suppression. Further, a frequency‐agile neural network (FANN) model is proposed based on the TDNN model. By adding the carrier frequency to the inputs of the network, the trained model can apply to all the trained carrier frequencies and is more friendly to the frequency‐hopping scenarios. Experiments were carried out on a 2–30 MHz HF transmitter testbench. Measurement results show that the harmonic‐to‐fundamental power ratio, the adjacent channel power ratio (ACPR), and the error vector magnitude (EVM) performances were all improved by more than 20 dB. Compared with the MP model, the unwanted spurs can be suppressed by up to 22 dB. In addition, the number of total model coefficients of the proposed FANN model is only 22% of that of the TDNN model under the frequency‐hopping scenario. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper proposes a single and dual‐band compatible digital predistortion (SDBC‐DPD) for broadband transmitters with carrier aggregation. Since complicated spectrum scheduling, the stimuli of the power amplifiers (PAs) can be single‐band and dual‐band. The proposed SDBC‐DPD scheme can well linearize a dual‐band signal in a conventional 1‐D‐DPD way utilizing a spectrum splicing and segmentation method. A series of experiments were carried out on a dual‐band test bench based on a 3.0–4.0 GHz PA. The stimuli with different bandwidths and sampling rates were used in the experiments. Measurement results show that the SDBC‐DPD can well mitigate the nonlinearity in the dual‐band signals and needs a much lower sampling rate for model identification. [ABSTRACT FROM AUTHOR]