Research On Band-limited Digital Predistortion Technique For 100-MHz Signal B Andwidth Power Amplifier

Power Amplifier(PA)is a critical physical component in wireless transmitters,improving the signal-to-noise ratio and increasing the received signal’s accuracy at the receiver.The PA efficiency is seriously degraded,and its output signal will also produce spectrum leakage under the PA’s nonlinear characteristics in the communication scenario of 100MHz signal bandwidth.The digital predistortion(DPD)technique,which is one of the linearization methods of power amplifier,considers high efficiency and linearization.The bandwidth of wireless signals has reached the level of 100-MHz with the development of the wireless communication technique.DPD technique faces severe challenges at the influence of the precise sampling of the large-bandwidth signal.Therefore,the bottleneck problem of broadband signal sampling faced by the conventional DPD method in the communication scenario of 100-MHz signal bandwidth can be effectively resolved by the proposal of the band-limited DPD method.Too large predistorted signal processing bandwidth is required by the existing bandlimited DPD method.It will lead to an increased transmission bandwidth with the increase of the modulation signal bandwidth.At the same time,the band-limited DPD model complexity increases due to the rise in the memory depth of the model when the feedback pass-band filter is introduced.How to further reduce the system bandwidth and model complexity is a new challenge for band-limited digital predistortion.To address this problem,a band-limited DPD method with an adjustable signal sampling rate is proposed in this paper,which attempts to remove the feedback bandpass filter and comprehensively considers the requirements of the predistorted signal processing bandwidth and feedback sampling bandwidth.It can realize the DPD parameter’s estimation and correction through the low sampling rate signals.Theoretical analysis and experimental verification show that the reduced requirements of the predistorted signal bandwidth,the feedback bandwidth and the transmission bandwidth will be required by the proposed method without sacrificing linearization performance.Compared with the existing bandlimited DPD methods,the proposed method can effectively avoid the memory depth disaster caused by the feedback pass-band filter and reduce the model complexity.