光线性化调制器的特性

在１５５０nm波段，调制器的线性化补偿方案有几种，非线性补偿有调制器并联犤１犦犤２犦、多级调制器的串联犤３犦、双调制法犤４犦、预失真法犤５犦犤６犦、前馈补偿犤７犦犤８犦等。其中用得最多的是预失真法。而光线性化调制技术具有线性最佳的特点，因而得到愈来愈多的重视。本文主要是对光线性化调制器的标准进行分析，以求得到重视。１光线性化调制器的结构光线性化调制器的结构如图１所示，它包含有２个调制器、２个定向耦合器、１路光输入、２路光输出。在合理偏置下，每一个调制器仍具有消除CSO的特性。当两个调制器上的射频驱…     

光纤AM—CATV外调制发射机中非线性补偿及受激布里渊散射抑制技术

本文介绍了光纤AM-CATV外调制发射机中光学线性化调制器非线性补偿技术及预失真补偿技术，以及附加相移调制法与激光器高频抖动法等受激布里渊散射（SBS）抑制技术。     

带通∑—Δ调制器的双线性变换设计方法

本文论述了带通式∑-Δ调制器的双线性变换设计方法，通过线性化的插入式网络分析技术，将带通式∑-Δ调制器的设计问题转化耿IIR带阻数字滤波器的设计问题，文章给出了该方法的原理和设计步骤，并对一位∑-Δ代码的产生和检验方法以及调制器的稳定性问题进行了说明了讨论，最后给出了利用Matlab的计算机仿真结果，结果表明，该方法简单可靠，便于计算机仿真和检验，可大大加快带通∑-Δ调制器的设计过程。     

光纤AM—CATV外调制传输系统中的关键技术

介绍了光纤ＡＭ－ＣＡＴＶ外调制传输技术中的关键技术,包括外调制器及其最佳偏置点的稳定控制技术;光学线性化调制器及预失真补偿等非线性补偿技术;以及附加相位调制法与激光器高频抖动法等受激布里渊散射（ＳＢＳ）的抑制技术。     

PIN调制器用于线性脉冲调制的可能性

本文分析了PIN调制器的电流调制特性,对其在线性坐标上呈现的高度非线性作了讨论,并进一步提出了采用对数网络使其线性化的电路补偿方法,这种方法在实验中已获得成功。     

RoF非线性链路对OFDM信号的影响

正交频分复用OFDM（Orthogonal Frequency Division Multiplexing）与光载无线电ROF（Radio OverFiber）技术结合为实现低成本、高速数据传输的无线网络提供了可能。但RoF链路的非线性降低了系统性能。丈中在分析Machzehnder调制器的静态模型基础上,提出用Volterra级数与冲击响应分析模型相结合模型化RoF非线性系统。在此模型基础上分析Mach-Zehnder调制器以及射频放大器非线性对OFDM信号的影响。仿真分析显示非线性会使OFDM信号频谱展宽,降低信号幅度,并且随着光调制指数的增加误差矢量,带外干扰增加。为OFDM-RoF系统的线性化处理以及系统光调制器调制指教的选择提供了理论依据。     

带通Σ-Δ调制器的双线性变换设计方法

本文论述了带通式Σ-Δ调制器的双线性变换设计方法,通过线性化的插入式网络分析技术,将带通式Σ-Δ调制器的设计问题转化为了IIR带阻数字滤波器的设计问题.文章给出了该方法的原理和设计步骤,并对一位Σ-Δ代码的产生和检验方法以及调制器的稳定性问题进行了说明和讨论,最后给出了利用Matlab的计算机仿真结果,结果表明,该方法简单可靠,便于计算机仿真和检验,可大大加快带通Σ-Δ调制器的设计过程.     

（超）高功率线型脉冲调制器技术方案综述

综述了国内外高功率线型脉冲调制器技术现状及所用开关管的水平。给出了开关管电压和电流受限制情况下，实现数百乃至数千兆瓦调制器的方案。提出了采用组合式调制器达到ＰＰＮ低阻抗的优点，对ｄｅ－Ｑ电路设计也提出了改进意见。     

光纤AM—CATV外调制发射机中的关键技术

本文介绍了光纤ＡＭ－ＣＡＴＶ外调制发射机中的关键技术,包括最佳偏置点的稳定控制技术光学线性化调制器及预失真补偿等非线性补偿技术;以及附加相位调制法与激光 高频抖动法等受激布里渊散射的抑制技术。     

单片机技术线性化和扩展线性范围的方法

在检测与转换技术的数据处理过程中，一个重要的方面就是非线性特性的线性化，在很多情况，线性化又是以牺牲线性测量范围及灵敏度为代价的，从而在很多既要求线性化好又要求测量范围大的场合，线性化成为一个棘手的问题。本文提出了一个借助于单片机技术线性化，又能扩展线性范围的方法，该方法改变了传统的线性化方法，可在同一最小二乘线性度指标下对非线性特性实现线性化，同时还可扩展线性测量范围。     

Linearized transmitters: an enabling technology for softwaredefined radio

Power amplifier and transmitter linearization techniques are now a mature technology, with feedforward systems installed in many US base station sites for both TDMA and CDMA systems. Similarly, transmitter linearization techniques, such as Cartesian loop and predistortion, have been employed in mobile and portable equipment, and these have enabled a number of systems (e.g., iDEN in the United States and TETRA in Europe) to be realizable from a power consumption, cost, and size perspective. Such techniques are essential in the realization of an efficient and cost-effective software-defined radio system, whether deployed in a base station or a handset, and are thus a key enabling technology, without which SDR will not succeed. This article examines the current status of power amplifier and transmitter linearization technologies for mobile and base station equipment, and highlights some of the novel base station and network topologies now emerging based on these techniques. In many cases, these new topologies will revolutionize the way a cellular network is constructed and lead to very substantial cost reductions for a network operator     

功率放大器数字基带自适应预失真技术研究进展

阐述了目前国内外功率放大器（PA）线性化技术的研究状况，重点研究了其中最有应用前景的数字基带自适应预失真技术及其最新研究进展，分析并指出了相关方法的优缺点，并对其发展前景进行了展望。     

高功率放大器线性化技术研究

综述了目前国内外关于高功率线性放大器(High Power Amplifier,HPA)线性化技术的研究状况,分析了HPA非线性对OFDM信号的影响;总结分析了一些常用、典型线性化技术的优、缺点及适用范围;展望了HPA线性化技术的发展前景,系统地指出了关于HPA线性化技术进一步研究应注意的问题。     

Adaptive Digital Feedback Predistortion Technique for Linearizing Power Amplifiers

We have developed a new adaptive digital predistortion (DPD) linearization technique based on analog feedback predistortion (FBPD). The lookup-table-based feedback input can remove the bandwidth limitation of the feedback circuit related to the loop delay, and suppress feedback oscillation by accurate digital control of the feedback signal. Moreover, the predistortion (PD) signal can be extracted very efficiently. By combining the feedback linearization and DPD linearization techniques, the performance of the predistorter is enhanced significantly compared to the conventional DPD. To clearly visualize the characteristics of digital FBPD (DFBPD), we have compared it to the conventional DPD based on the recursive least square algorithm using Matlab simulation. The results clearly show that the new method is a good linearization algorithm, better than a conventional DPD. For the demonstration, a Doherty power amplifier with 180-W peak envelope power is linearized using the proposed DFBPD. For a 2.14-GHz forward-link wideband code-division multiple-access signal, the adjacent channel leakage ratio at 2.5-MHz offset is -58 dBc, which is improved by 15 dB at an average output power of 43 dBm     

A Framework for Spectral Artifact Corrections in X-Ray CT

The spectral artifact problem in X-ray computed tomography (CI) is well known. Many techniques have been suggested to correct for this problem, including linearization methods, iterative methods, and dual spectrum methods.     

射频功放的立方预失真线性化技术

预失真技术是射频功率放大器线性化技术中的一种,与其他线性化技术相比具有电路简单可靠、性能优良、成本低廉等优点。立方预失真技术是其中的一种,该技术易于设计调试,且性能优良。对射频功率放大器的非线性特性进行了深入的理论分析,剖析了非线性失真产生的根源。说明了预失真技术的工作原理和结构,重点讨论了立方预失真器的原理和结构,并且给出了理论和实际系统的仿真结果。     

查找表联合记忆效应补偿技术的宽带自适应预失真算法

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。     

Linearizability of TWTAs using predistortion techniques

Predistortion linearization is a very effective technique for improving the linearity and efficiency of traveling wave tube (TWT) amplifiers. In this paper, we will study the effectiveness of predistortion techniques for TWT linearization using single-tone, two-tone, and quadrature-amplitude-modulation signals. The results from a series of predistortion linearization experiments for five TWTs covering L-, C-, Ku-, and Ka-bands and including both helix- and coupled-cavity TWTs will be presented. We will demonstrate the additional improvement of fifth-order predistortion linearization over the more commonly used third-order predistortion linearization. To circumvent the complexity and limited availability of a pure fifth-order linearizer, a technique for realizing nonlinear functions of order greater than or equal to five using cascaded third-order nonlinear functions is described. The technique can be used to efficiently generate higher order nonlinearities for predistortion linearization applications. We will demonstrate experimentally that the use of two cascaded third-order functions is comparable to a pure fifth-order implementation in performance.     

A New Wideband Adaptive Digital Predistortion Technique Employing Feedback Linearization

We develop a new wideband digital feedback predistortion (WDFBPD) technique for modulated signals with wide bandwidths by combining digital feedback predistortion (DFBPD) linearization and memory-effect compensation techniques. For the experiments, a class-AB amplifier using an LDMOSFET with 90-W peak envelope power is employed. The proposed technique is compared with existing DFBPD and memory polynomial (MP) techniques for a 2.14-GHz forward-link WCDMA 2FA signal with 10-MHz carrier spacing. The experimental results show that the new WDFBPD technique has better linearization performance than conventional DFBPD and lower computational complexity than the MP technique.     

Energy-Efficient Digital Predistortion With Lookup Table Training Using Analog Cartesian Feedback

We demonstrate energy-efficient low-complexity adaptive linearization for wideband handset power amplifiers (PAs). Due to power overhead and complexity, traditional wideband linearization techniques such as adaptive digital predistortion (DPD) thus far have not been used for wideband handset transmitters. Our energy-efficient lookup table training strategy resulted in a training energy of 1.83 nJ/entry for a 5-MHz bandwidth WiMAX orthogonal frequency division multiple access (OFDMA) transmission, which represents more than 40times improvement over state-of-the-art DPD implementations. Our experimental prototype transmitter achieves a maximum of 9.9-dB improvement of adjacent channel leakage power at 5.15-MHz offset with 22.0-dBm channel power in the 5-MHz bandwidth WiMAX-OFDMA transmission. This linearity improvement offers 26.5% savings in PA power consumption by reducing power backoff.