本文關(guān)鍵詞： 非線性 功率放大器 記憶效應 行為模型 徑向基函數(shù)　出處：《寧波大學》2015年碩士論文　論文類型：學位論文

【摘要】：由于其優(yōu)良的逼近能力,神經(jīng)網(wǎng)絡正逐漸成為一種越來越有吸引力的解決功率放大器建模的方案。在不清楚功率放大器內(nèi)部結(jié)構(gòu)的基礎上,人工神經(jīng)網(wǎng)絡也可以根據(jù)采集得到的功放輸入以及輸出數(shù)據(jù),來學習到該電路的內(nèi)部行為。因此,本文首先從單波段射頻功率放大器的非線性特點著手研究,然后介紹了功率放大器的記憶效應,對該效應引起的原由進行了分析,并介紹了幾種常見的功率放大器記憶模型,以及這些模型之間的關(guān)系;隨后介紹了神經(jīng)網(wǎng)絡相關(guān)理論知識,利用神經(jīng)網(wǎng)絡中的徑向基函數(shù)(RBF)神經(jīng)網(wǎng)絡對射頻功放進行行為模型建立;最后對雙波段功率放大器的非線性特性進行理論研究以及相關(guān)的一系列實驗,并對雙波段射頻功放進行建模。主要工作包括:(1)研究單波段射頻功放的非線性特性理論,闡述了給射頻功放帶來這種失真的根源,以及非線性失真對信號放大的一些影響;接著對記憶效應進行分類以及分析其產(chǎn)生的緣由,其中記憶效應與輸入信號的帶寬密不可分,帶寬越寬記憶效應越深越明顯,此時,AM/AM以及AM/PM曲線發(fā)散的越厲害,所以記憶效應對建模精度造成的影響不容小覷。本文后面的建模等相關(guān)工作都是在該理論的指導下所進行的。(2)研究了單波段射頻功放的行為模型,提出了兩種基于神經(jīng)網(wǎng)絡的單波段射頻功放行為模型:第一種是交叉實數(shù)時延徑向基函數(shù)神經(jīng)網(wǎng)絡,第二種是遞歸型徑向基函數(shù)神經(jīng)網(wǎng)絡。第一種模型在傳統(tǒng)RBF神經(jīng)網(wǎng)絡模型基礎上,在輸入端加入了多項式交叉項和延遲項,交叉項用于模擬功放的強非線性,延遲項用于模擬功放的記憶效應。實驗結(jié)果表明:該模型可以適合射頻功率放大器行為模型,并且效果非常好,與反向傳播(back propagation,BP)網(wǎng)絡的實數(shù)延時神經(jīng)網(wǎng)絡相比,收斂速度快,大大縮短了訓練時間。為了進一步提高建模的精度,接著提出了遞歸型徑向基函數(shù)神經(jīng)網(wǎng)絡模型,該模型在前一個模型的基礎上將輸出項反饋到模型的輸入端進行功放建模,實驗證明,對于強非線性的射頻功率放大器的建模,模型效果很好,擬合精度高,且收斂速度更快。(3)研究了雙波段射頻功放的行為模型,首先分析了雙波段的非線性特性,進而闡述了雙波段對于現(xiàn)代通信的重要性,接著闡述了雙波段信號如何同步以及獲取問題,最后提出了基于徑向基函數(shù)網(wǎng)絡的射頻功放雙波段行為模型。
[Abstract]:Because of its excellent approximation ability, neural network is becoming a more and more attractive solution to the modeling of power amplifier. The artificial neural network can also learn the internal behavior of the circuit according to the input and output data of the power amplifier. Therefore, the nonlinear characteristics of the single-band RF power amplifier are studied in this paper. Then, the memory effect of power amplifier is introduced, and the original cause of this effect is analyzed, and several common memory models of power amplifier are introduced, as well as the relationship between these models. Then the related theory knowledge of neural network is introduced and the behavior model of RF power amplifier is established by using the radial basis function (RBF) neural network in the neural network. Finally, the nonlinear characteristics of dual-band power amplifier are studied theoretically and a series of experiments are carried out, and the model of dual-band RF power amplifier is established. The main work includes: 1) studying the theory of nonlinear characteristics of single-band RF power amplifier. The source of this distortion to RF power amplifier and the influence of nonlinear distortion on signal amplification are expounded, and then the memory effect is classified and analyzed, in which the memory effect is closely related to the bandwidth of input signal. The wider the bandwidth, the deeper the memory effect is, and the more the AM / AM and AM/PM curves diverge, Therefore, the effect of memory effect on modeling accuracy is not to be underestimated. In this paper, modeling and other related work are carried out under the guidance of this theory. (2) the behavior model of single band RF power amplifier is studied. Two kinds of radio frequency power amplifier behavior models based on neural network are proposed. The first one is crossover real number delay radial basis function neural network. The second is the recurrent radial basis function neural network. The first model is based on the traditional RBF neural network model, and the polynomial crossover term and the delay term are added to the input end. The crossover term is used to simulate the strong nonlinearity of the power amplifier. The delay term is used to simulate the memory effect of power amplifier. The experimental results show that the model is suitable for the behavior model of RF power amplifier, and the effect is very good. Compared with the real number delay neural network of back-propagation propagation, the convergence speed of the model is faster than that of BPN. In order to further improve the accuracy of modeling, a recurrent radial basis function neural network model is proposed, in which the output term is fed back to the input side of the model for power amplifier modeling. Experimental results show that the model is effective, accurate and convergent, and the behavior model of dual-band RF power amplifier is studied. Firstly, the nonlinear characteristics of dual-band RF power amplifier are analyzed. Then, the importance of dual-band for modern communication is expounded. Then, the synchronization and acquisition of dual-band signals are discussed. Finally, a dual-band behavior model of RF power amplifier based on radial basis function network is proposed.
【學位授予單位】：寧波大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN722.75;TP183

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本文編號：1547030