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自适应数字预失真放大器的算法研究 总被引:1,自引:0,他引:1
由于功率放大器特性随温度,供电电压等因素的变化而改变,为了保证预失真功率放大器稳定工作,预失真系统的自适应性能就显得非常重要.基于查找表的预失真放大器广泛采用最小均方(least-mean-square,LMS)自适应算法.介绍了基于查找表的预失真放大器的基本结构,并根据步长参数和误差之间的非线性关系提出了一个新的变步长LMS算法.最后用MATLAB搭建了一个自适应预失真器的仿真系统.仿真表明,在迭代500次时,该算法对预失真放大器失真效果的改进明显优于以前的算法. 相似文献
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数字基带预失真自适应算法改进与性能分析 总被引:1,自引:0,他引:1
文章首先介绍了数字基带预失真的自适应算法,针对基于多项式的实现方式分析比较了LMS和RLS算法,然后研究基于查找表的各种自适应算法,提出了一种改进的查找表预失真组合算法。仿真结果表明,这种算法可以很好地满足查找表预失真自适应环节的要求。 相似文献
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功率放大器是无线通信系统重要组成部分,目前通信系统中采用具有高效频谱利用率的线性调制技术,要求功率放大器必须具有良好的线性特性。线性化技术成为提高功率放大器效率的关键。文中采用最陡下降法、LMS算法和分段变步长算法三种自适应算法分别对功率放大器预失真方法进行了设计,仿真结果表明,分段变步长算法提高了收敛速度,并保证了稳定性,大大减小了带内和带外失真。 相似文献
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OFDM技术具有频谱利用率较高和抗多径干扰能力强的优点.但OFDM信号较高的峰值平均功率比对功率放大器的线性度提出了更高的要求.针对有记忆功率放大器,提出了一种基于查找表的自适应预失真方案,该方案利用多项式法补偿放大器的非线性特性,并将其应用于OFDM系统中.仿真结果表明,该方案能够很好地改善预失真效果,并且在算法收敛速度和节约硬件资源方面都有所提高. 相似文献
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针对查找表方法的功率放大器自适应数字预失真技术需对全部输入信号进行处理且计算量较大的问题,提出了一种加窗自适应数字预失真算法。只需将窗口范围内的一部分输入信号进行预失真处理,能够有效节省资源,并使预失真表查找表项利用更加合理,加快了运算速度。仿真结果表明,功率放大器的动态范围有所增大。 相似文献
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自适应预失真技术是用于补偿高功率放大器非线性失真的一种有效技术.文中介绍了用LMS算法来实现的自适应预失真,以补偿功率放大器的非线性.计算机仿真结果表明,该自适应预失真技术具有实现复杂度低,收敛速度快的特点. 相似文献
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为了能够对记忆型功率放大器线性化处理,并能一定程度克服其记忆效应,该文介绍一种自适应数字预失真器。该数字预失真器采用查找表与记忆效应补偿技术相结合的方法,并且利用内插值方法有效减小了查找表幅度量化过程产生的误差。相比记忆多项式预失真器,这种预失真器的计算复杂度较小,却能够得到与其相近的线性化效果。基于功率放大器记忆多项式模型,利用OFDM(Orthogonal Frequency Division Multiplexing)宽带信号验证该文提出的预失真器对记忆型非线性功率放大器的良好线性化效果。 相似文献
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Sheng-Lung Cheng Wen-Rong Wu Chun-Hsien Peng Jen-Yang Liu Chen-Jui Hsu Paul Liang 《Analog Integrated Circuits and Signal Processing》2017,90(1):125-136
Digital predistortion has been proved to be an effective remedy for the nonlinear distortion in radio-frequency power amplifier. Unfortunately, conventional digital predistorters (DPDs) developed for single-band transmitters can not be directly applied to concurrent dual-band. To solve the problem, DPDs with two dimensional memory polynomials were then proposed. Although they can provide good performance, its computational complexity is high for the estimation of polynomial coefficients. Look-up-table (LUT) based DPDs, developed for single-band transmitters, can effectively solve the problem. However, there are limited studies about LUT based DPDs for concurrent dual-band transmitters. In this paper, we propose a two-dimensional LUT based Hammerstein DPD to solve the problem. Analyzing the signals on both bands, we propose a new adaptive algorithm with the gradient-descent and recursive-least-squares (RLS) methods to train the DPD iteratively. With the proposed method, the computational complexity in the identification of the DPDs can be significantly reduced. Finally, simulations and experiments are conducted to demonstrate that the performance of the proposed DPD is comparable to that of the polynomial based DPD. 相似文献
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数字预失真功放的输出动态提升技术在现代功率放大器设计和研究中已成为一个重要的课题。本文基于数字预失真功放自身特征以及自适应信号处理技术,提出了一种全新的输出动态提升技术。理论分析和试验结果表明:采用该新型技术的数字预失真功放不仅输出动态得到了大幅度提升,而且线性也有一定程度改善。 相似文献
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基于非迭代算法和非直接学习结构的查询表TWTA预失真器 总被引:1,自引:0,他引:1
提出了一种基于查询表和非直接学习结构的适用于行波管放大器(TWTA)的基带预失真器。通过引入线性增长的周期性训练序列和失真检测算法,实现了预失真器非迭代方法的参数捕获。与普通查询表预失真器相比,该预失真器不但能离线处理失真数据,而且不需要使用基于最小代价函数的迭代算法更新预失真器查询表中的内容,从而能在降低对系统处理速度要求的同时,回避了算法收敛性问题。仿真结果表明,所提预失真器可大大降低由TWTA非线性所引入的带内失真和频谱再生。 相似文献
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In this paper, an adaptive digital predistortion based on a memory polynomial model is proposed in order to linearize the power amplifier with memory effect. The coefficients of the power amplifier model have been extracted using a least square method and those of predistortion have been identified by applying an indirect learning structure. Finally, the performance of digital predistortion has been demonstrated using the simulation of the power amplifier and the digital predistortion excited by a modulated 16 QAM signal in Matlab software. According to the simulation results, the criterion of adjacent channel power ratio (ACPR) declined by around 15 dB and the input/output power spectrum density of the power amplifier has quite similar curves. The linearized power amplifier output spectrum demonstrates the superiority of the proposed predistorter in eliminating the spectral regrowth which is caused by the memory effect in comparison to the other linearization methods. 相似文献
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Dynamically optimum lookup-table spacing for power amplifier predistortion linearization 总被引:2,自引:0,他引:2
Chih-Hung Lin Hsin-Hung Chen Yung-Yi Wang Jiunn-Tsair Chen 《Microwave Theory and Techniques》2006,54(5):2118-2127
The lookup-table-based digital adaptive predistortion (DAPD-LUT) approaches are low cost and effective for power amplifier (PA) linearization in wireless applications. However, most existing DAPD-LUT schemes are sub-optimum because they adopt uniformly spaced LUTs regardless of the system state information (SSI), i.e., the PA characteristics and the input signal statistics. Other existing DAPD-LUT schemes assume either full or partial knowledge of the SSI to optimize and then to freeze the LUT spacing. Without prior knowledge of the SSI, we propose an SSI-learning low-complexity procedure to optimize the LUT spacing for a DAPD-LUT scheme. The proposed procedure is capable of online adapting the LUT spacing for PAs with various nonlinear characteristics, for input signals with various statistics, and for wireless environments with various time-varying properties. 相似文献
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Boumaiza S. Jing Li Jaidane-Saidane M. Ghannouchi F.M. 《Microwave Theory and Techniques》2004,52(12):2670-2677
This paper reports on an integrated adaptive digital/RF predistorter using a nonuniform spaced lookup table (LUT) and in-phase/quadrature (I/Q) RF vector multiplier (VM). The LUT contents are directly deduced from the baseband input and output signals of the power amplifier (PA). In addition, a new nonlinear indexing function of the predistortion LUT with built-in dependence on the PA nonlinearity is proposed. This function is made to be robust to the input signal statistics. A comparison of this new indexation method with conventional approaches, namely, power and logarithmic power indexation functions, is carried out. The superiority of the proposed scheme is demonstrated in particular for class-AB amplifiers where the gain of the PA varies over the whole input range of the drive signal. The measured output spectrum of a linearized 90-W peak lateral double-diffused metal-oxide-semiconductor PA reveals a significant reduction of the power emission at the adjacent channels of approximately 15 dB under IS95, single-carrier, and multicarrier wide-band code-division multiple-access signals. The experimental evaluation is carried out using an RF/digital predistorter prototype that mainly includes an envelope detector, a linear I/Q RF VM, field-programmable gate array and digital signal processor, and fast analog/digital and digital/analog converters. 相似文献