臺灣博碩士論文加值系統

本論文針對寬頻功率放大器造成之非線性問題進行數位預失真技術研究。在無線通訊系統中，傳送端皆需要藉由功率放大器提升發射之功率，但功率放大器存在著線性度之問題，此問題將導致鄰近通道之干擾及信號失真…等問題。通常採用倒退(Back-off)法避免非線性之問題，然而此方法將降低功率放大器之頻譜使用效能，為了提升頻譜使用效能，本論文將採用基頻數位預失真之方式抑制非線性問題。其數位預失真之架構為間接學習之方式，利用功率放大器產生之非線性訊號與記憶多項式之模型求其反函數參數，再利用此參數將原始訊號進行數位預失真動作，可明顯抑制鄰近通道之干擾。本論文亦針對真實之功率放大器(如:SKYWORKS SKY66293與ITRI Small Cell PA)搭配寬頻模組(如:AD9375、ADRV9009)與寬頻儀器(NI PXIe-5646R)進行實測驗證。最後，結合發射端射頻不完美因子(如:頻率獨立之I/Q不平衡、頻率相依之I/Q不平衡與直流偏移等)與功率放大器非線性因子進行聯合調校技術之實測驗證，其調校程序為「先調校寬頻射頻不完美因子，再調校功率放大器非線性因子」，完成全系統之理論、模擬、儀器、模組、實務測試，達成高品質之通訊需求。

This thesis aims to study the digital predistortion techniques for the nonlinear problems caused by the broadband power amplifier. In the wireless communication system, the transmitter needs to increase the transmitting power by the power amplifier, but the power amplifier has a linearity problem, which creates some issues including the interference of adjacent channels and signal distortion. The back-off method is usually used to avoid the nonlinear problem. However, this method will reduce the spectral efficiency of the power amplifier. In order to improve the spectral efficiency, this thesis will use the digital predistortion (DPD) algorithm to solve the nonlinear problem. The DPD architecture is an indirect learning architecture, which uses the nonlinear signal of the power amplifier and the memory polynomial model to find the inverse function. Then, using this DPD parameters to predistort the original signal can significantly reduce the interference of adjacent channel. This thesis also performs experimental verification to real power amplifiers, e.g., SKYWORKS SKY66293 and ITRI Small Cell PA, which is integrated by broadband RF modules, e.g., AD9375, ADRV9009 and broadband instruments platform, e.g., NI PXIe-5646R. Finally, the joint calibration technology is proposed to overcome the PA nonlinear and RF impairment effects, e.g., frequency independent, dependent I/Q imbalances, and DC offset. For the calibration procedures, the procedure is the transmitter RF calibration being processed before the nonlinearity calibration of the power amplifier. To sum up, the thesis combines the theory, simulation, instrument, RF module, and the practical measurements to achieve the requirement of the wideband high equality communications.

摘要 i
ABSTRACT ii
致謝 iv
目錄 v
圖目錄 vii
表目錄 xi
第一章 緒論 1
1.1 研究動機與背景 1
1.2 論文章節架構 1
第二章 功率放大器之特性 2
2.1 前言 2
2.2 功率放大器之非線性特性 2
2.2.1 增益壓縮 2
2.2.2 鄰近通道功率比例 3
2.3 功率放大器之模型 5
2.3.1 Wiener Model 5
2.3.2 Hammerstein Model 6
2.3.3 Wiener Hammerstein Model 7
2.3.4 Memory Polynomial Model 7
2.4 間接學習架構之數位預失真技術 8
第三章 數位預失真技術研究 9
3.1 前言 9
3.2 記憶多項式建置功率放大器模型 10
3.2.1 原理介紹 10
3.2.2 利用MATLAB模擬結果 11
3.3 數位預失真技術介紹 13
3.3.1 最小平方法之原理介紹 13
3.3.2 最小平方法之MATLAB模擬結果 14
3.3.3 遞迴最小平方法之原理介紹 15
3.3.4 遞迴最小平方法之MATLAB模擬結果 16
3.3.5 最小平方法結合查表法之原理介紹 17
3.3.6 最小平方法結合查表法之MATLAB模擬結果 18
3.4 利用AD9375實測驗證數位預失真技術 20
3.4.1利用截去法改善PAPR 20
3.4.2針對SKYWORKS SKY66293功率放大器之實測驗證 22
3.4.3 針對ITRI Small Cell功率放大器之實測驗證 29
3.5 利用ADRV9009實測驗證ITRI Small Cell功率放大器數位預失真技術 33
第四章 整合發射端射頻不完美因子之調校與功率放大器非線性因子之數位預失真技術實測驗證 36
4.1 前言 36
4.2 實數平行濾波器估測發射端寬頻射頻不完美因子及預補償調校之介紹 38
4.3 利用NI儀器平台整合發射端射頻不完美因子之調校與功率放大器非線性因子之數位預失真技術實測驗證 42
4.3.1 結合發射端射頻不完美因子與SKYWORKS SKY66293功率放大器之實測驗證 44
4.3.2結合發射端射頻不完美因子與ITRI Small Cell功率放大器之實測驗證 50
4.4 多階係數之直流偏移估測與補償 56
4.4.1前言 56
4.4.2多階係數之直流偏移估計法 57
4.4.3利用AD9375實測多階係數之直流偏移估計法 58
第五章 結論 61
參考文獻 62

[1] L. Ding, G. T. Zhou, D. R. Morgan, Z. Ma, J. S. Kenney, J. Kim, C. R. Giardina, "A robust digital baseband predistorter constructed using memory polynomials", IEEE Trans. Commun., vol. 52, no. 1, pp. 159-165, Jan. 2004.
[2] L. Ding, "Digital Predistortion of Power Amplifiers for Wireless Applications", GA, Atlanta: Georgia Inst. Technol., 2004.
[3] Khaled M. Gharaibeh, Nonlinear Distortion in Wireless Systems: Modeling and Simulation with MATLAB, Hoboken, NJ, USA:Wiley, 2011.
[4] F. M. Ghannouchi, O. Hammi, M. Helaoui, Behavioral Modeling and Predistortion of Wideband Wireless Transmitters, Hoboken, NJ, USA:Wiley, 2015.
[5] D. R. Morgan, Z. Ma, J. Kim, M. G. Zierdt, J. Pastalan, "A generalized memory polynomial model for digital predistortion of RF power amplifiers", IEEE Trans. Signal Process., vol. 54, no. 10, pp. 3852-3860, Oct. 2006.
[6] https://www.mathworks.com/company/newsletters/articles/adaptive-dpd-design-a-top-down-workflow.html
[7] F. Li, B. Feuvrie, Y. Wang, W. C hen, "MP/LUT baseband digital predistorter for wideband linearization", Electron. Lett., vol. 47, no. 19, pp. 1096-1098, Sept. 2011.
[8] Y. S. Cho, J. Kim, W. Y. Yang, C.-G Kang, MIMO-OFDM Wireless Communications With MATLAB, Singapore: Wiley (Asia) Pte. Ltd., 2010.
[9] 李佳芳, " 寬頻射頻不完美校正技術研究與實測驗證 ",元智碩士論文,July 2018.
[10] C.-J. Hsu, W.-H. Sheen, "Joint calibration of transmitter and receiver impairments in direct-conversion radio architecture", IEEE Trans. Wireless Commun., vol. 11, no. 2, pp. 832-841, Feb. 2012.
[11] L. Ding, Z. Ma, D. R. Morgan, M. Zierdt, G. T. Zhou, "Frequency-dependent modulator imbalance in predistortion linearization systems: Modeling and compensation", Proc. Asilomar Conf. Signals Syst. Comp., pp. 688-692, Nov. 2003.
[12] L. Anttila, P. Handel, and M. Valkama, "Joint mitigation of power amplifier and I/Q modulator impairments in broadband direct-conversion transmitters," IEEE Transactions on Microwave Theory and Techniques, vol. 58, no. 4, pp. 730-739, 2010.
[13] https://www.analog.com/media/en/technical-documentation/data-sheets/AD9375.pdf
[14] http://www.analog.com/en/design-center/landing-pages/001/transceiver-evaluation-software.html
[15] https://www.analog.com/media/en/technical-documentation/data-sheets/ADRV9009.pdf
[16] http://www.ni.com/datasheet/pdf/en/ds-422