An under-Sampling Restoration Digital Predistortion Technique Based on Landweber Iteration Algorithm
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摘要: 传统宽带数字预失真(DPD)为了更好地矫正功率放大器(PA)非线性特性，通常要求反馈通道带宽达到发送信号带宽的5倍，相应地要求更高采样率的模数转换器(ADC)，这将导致数字预失真系统面临着硬件成本和能耗问题。针对这一问题，该文提出一种基于Landweber迭代算法的欠采样恢复(USR)数字预失真(Landweber-USR DPD)技术。这种以内外循环的方式进行处理，可将反馈通道带宽从理论要求的5倍降低至2倍，以良好的质量从欠采样的功放输出信号中恢复全频带的输出信号，使还原出的数据更接近真实的功放输出信号，以实现更好的预失真效果。实验选用基于单管氮化镓(GaN)器件的宽带F类功率放大器，在1.8 GHz工作频点下用5 MHz的长期演进(LTE)信号激励，反馈ADC速率分别设置为全采样速率(40 Msps)和欠采样速率(10 Msps)。实验结果充分证明了Landweber迭代算法恢复功放数据的可靠性以及Landweber-USR DPD技术的有效性，为宽带通信系统中数字预失真技术的工程实现提供了有效降低ADC采样率的思路和方法。
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关键词:
- 数字预失真 /
- 欠采样 /
- 内外循环 /
- Landweber迭代
Abstract: In order to better correct the nonlinear characteristics of Power Amplifier (PA), conventional broadband Digital PreDistortion (DPD) requires usually the feedback channel bandwidth to be 5 times of the transmitting signal bandwidth, and Analog to Digital Converter (ADC) with higher sampling rate is required accordingly, which will lead to the hardware cost and energy consumption problems of digital predistortion system. To solve this problem, an Landweber iterative algorithm-based UnderSampled Restoration (USR) Digital PreDistortion method (Landweber-USR DPD) is propsed. It is processed in an internal and external loop, which can recover the full-band output signals from the undersampled PA output signals under the requirements that the sampling rate requirement of ADC is reduced from 5 times to twice. And the restored data is closer to the real PA output signals to achieve better pre-distortion effect. In experiment, a single-device Gallium Nitride (GaN) broadband class-F PA is excited by 5 MHz-LTE signal in 1.8 GHz frequency. The feedback ADC rate is set as full sampling rate (40 Msps) and undersampling rate (10 Msps), respectively. The experimental results fully demonstrate the reliability of Landweber iterative algorithm and the effectiveness of Landweber-USR DPD technology, which can provide an idea and method for effectively reducing ADC sampling rate in the engineering implementation of digital predistortion technology in broadband communication systems. -
表 1 USR和Landweber-USR实验结果优缺点比较
算法名称 迭代次数 还原效果NRMSE(%) 线性化效果ACPR(dB) USR 6 3.29 –47.23 Landweber-USR 外循环6 2.04 –48.92 内循环50 
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[1] ONOE S. 1.3 Evolution of 5G mobile technology toward 1 2020 and beyond[C]. 2016 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, USA, 2016: 23–28. doi: 10.1109/ISSCC.2016.7417891. [2] SHAFI M, MOLISCH A F, SMITH P J, et al. 5G: A tutorial overview of standards, trials, challenges, deployment, and practice[J]. IEEE Journal on Selected Areas in Communications, 2017, 35(6): 1201–1221. doi: 10.1109/JSAC.2017.2692307 [3] NEININGER P, FRIESICKE C, KRAUSE S, et al. A sequential power amplifier at 3.5 GHz for 5G applications[C]. 2017 47th European Microwave Conference (EuMC), Nuremberg, Germany, 2017: 284–287. doi: 10.23919/EuMC.2017.8230855. [4] RANGAN S, RAPPAPORT T S, and ERKIP E. Millimeter-wave cellular wireless networks: Potentials and challenges[J]. Proceedings of the IEEE, 2014, 102(3): 366–385. doi: 10.1109/JPROC.2014.2299397 [5] KIM J and KONSTANTINOU K. Digital predistortion of wideband signals based on power amplifier model with memory[J]. Electronics Letters, 2001, 37(23): 1417–1418. doi: 10.1049/el:20010940 [6] WOOD J. System-level design considerations for digital pre-distortion of wireless base station transmitters[J]. IEEE Transactions on Microwave Theory and Techniques, 2017, 65(5): 1880–1890. doi: 10.1109/TMTT.2017.2659738 [7] GILABERT P L, VEGAS D, REN Zhixiong, et al. Design and digital predistortion linearization of a wideband outphasing amplifier supporting 200 MHz bandwidth[C]. 2020 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR), San Antonio, USA, 2020: 46–49. doi: 10.1109/PAWR46754.2020.9035997. [8] SHI Bo. Digital Predistortion linearization of wideband transmitter for high data rate satellite communications[C]. 2019 IEEE Asia-Pacific Microwave Conference (APMC), Singapore, 2019: 1589–1591. doi: 10.1109/APMC46564.2019.9038220. [9] 曹韬, 刘友江, 杨春, 等. 高效宽带包络跟踪系统电路性能优化及非线性行为校正[J]. 电子与信息学报, 2020, 42(3): 787–794. doi: 10.11999/JEIT190275CAO Tao, LIU Youjiang, YANG Chun, et al. Circuits optimization and system linearization for high efficiency and wideband envelope tracking architecture[J]. Journal of Electronics &Information Technology, 2020, 42(3): 787–794. doi: 10.11999/JEIT190275 [10] FRANK W A. Sampling requirements for Volterra system identification[J]. IEEE Signal Processing Letters, 1996, 3(9): 266–268. doi: 10.1109/97.536597 [11] 兰榕, 胡欣, 邹峰, 等. 基于循环平稳特性的欠采样宽带数字预失真研究[J]. 电子与信息学报, 2020, 42(5): 1274–1280. doi: 10.11999/JEIT190105LAN Rong, HU Xin, ZOU Feng, et al. Research of low sampling frequency broadband digital predistortion with cyclostationary characteristics[J]. Journal of Electronics &Information Technology, 2020, 42(5): 1274–1280. doi: 10.11999/JEIT190105 [12] KOEPPL H and SINGERL P. An efficient scheme for nonlinear modeling and predistortion in mixed-signal systems[J]. IEEE Transactions on Circuits and Systems II: Express Briefs, 2006, 53(12): 1368–1372. doi: 10.1109/TCSII.2006.882232 [13] ZHU Anding, DRAXLER P J, YAN J J, et al. Open-loop digital predistorter for RF power amplifiers using dynamic deviation reduction-based volterra series[J]. IEEE Transactions on Microwave Theory and Techniques, 2008, 56(7): 1524–1534. doi: 10.1109/TMTT.2008.925211 [14] CAO Wenhui, LI Yue, and ZHU Anding. Digital suppression of transmitter leakage in FDD RF transceivers: aliasing elimination and model selection[J]. IEEE Transactions on Microwave Theory and Techniques, 2018, 66(3): 1500–1511. doi: 10.1109/TMTT.2017.2772789 [15] YU Chao, GUAN Lei, ZHU Erni, et al. Band-limited volterra series-based digital predistortion for wideband RF power amplifiers[J]. IEEE Transactions on Microwave Theory and Techniques, 2012, 60(12): 4198–4208. doi: 10.1109/TMTT.2012.2222658 [16] MA Yuelin, YAMAO Y, AKAIWA Y, et al. Wideband digital predistortion using spectral extrapolation of band-limited feedback signal[J]. IEEE Transactions on Circuits and Systems I: Regular Papers, 2014, 61(7): 2088–2097. doi: 10.1109/TCSI.2013.2295897 [17] WANG Haoyu, LIU Falin, and TAO Wei. Robust and fast iterative algorithm based on Levenberg-Marquardt and spectral extrapolation for wideband digital predistortion of RF power amplifiers[C]. 2015 IEEE International Wireless Symposium (IWS 2015), Shenzhen, China, 2015: 1–4. doi: 10.1109/IEEE-IWS.2015.7164579. [18] LIU Youjiang, YAN J J, DABAG H T, et al. Novel technique for wideband digital predistortion of power amplifiers with an under-sampling ADC[J]. IEEE Transactions on Microwave Theory and Techniques, 2014, 62(11): 2604–2617. doi: 10.1109/TMTT.2014.2360398 [19] YU Chao, LU Qianyun, YIN Hang, et al. Linear-decomposition digital predistortion of power amplifiers for 5g ultrabroadband applications[J]. IEEE Transactions on Microwave Theory and Techniques, 2020, 68(7): 2833–2844. doi: 10.1109/TMTT.2020.2975637 [20] LI Yue, WANG Xiaoyu, and ZHU Anding. Sampling rate reduction for digital predistortion of broadband RF power amplifiers[J]. IEEE Transactions on Microwave Theory and Techniques, 2020, 68(3): 1054–1064. doi: 10.1109/TMTT.2019.2944813 [21] WANG Peiyuan and ZHOU Haiyun. Adaptive Landweber image reconstruction with an optimal presetting method[C]. 2013 Ninth International Conference on Natural Computation (ICNC), Shenyang, China, 2013: 1289–1293. doi: 10.1109/ICNC.2013.6818177. -
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