工学硕士学位论文
A COMPREHENSIVE ANALYSIS AND SIMULATION OF
IMD IN RF POWER AMPLIFIERS
朱伟
哈尔滨工业大学
2007年7月
国内图书分类号：TN830.6
国际图书分类号：621.38
带写字板的椅子工学硕士学位论文
射频功率放大器互调失真的综合
分析与仿真
硕士研究生：朱伟
导师：林茂六教授
申请学位级别：工学硕士
学科、专业：信息与通信工程
所在单位：电子与信息技术研究院
答辩日期：2007年7月
授予学位单位：哈尔滨工业大学
Classified Index：TN830.6
U.D.C: 621.38
Dissertation for the Maste’s Degree in Engineering
A COMPREHENSIVE ANALYSIS AND
SIMULATION OF
IMD IN RF POWER AMPLIFIERS
殡仪馆焚化炉Candidate：Zhu Wei
Supervisor：Prof. Lin Maoliu
Academic Degree Applied for：Master of Engineering Specialty：Information and Communication
Engineering
Affiliation：School of Electronics and
Information Technology
Date of Defence：July, 2007
Degree-Conferring-Institution：Harbin Institute of Technology
柔性电路哈尔滨工业大学工学硕士学位论文
摘要
随着无线通信技术的飞速发展，人们为了追求更高的频谱利用率和数据传输速率，广泛采用QPSK和QAM等线性调制技术。这些包络变化的线性调制信号经过非线性射频功率放大器后会产生互调失真，造成严重的码间干扰和邻近信道干扰。为了保证通信质量需要使用高线性的功率放大器，而高线性的功率放大器通常效率不高。为了解决这个问题，需要了解射频功率放大器的非线性特性，而不是单纯的通过外加电路牺牲效率来换线性。另一方面为保证通信质量，各种无线系统中对非线性失真都有严格的指标，定量描述这些非线性指标对指导系统设计也具有重要的指导意义。
本文首先从射频功率放大器非线性分析的基础出发，详细讨论了射频功率放大器非线性失真的基本概念以及非线性分析的理论和技术，并对各种非线性技术进行了总结和对比；对其中的谐波平衡分析技术用ADS实例仿真进行了介绍和说明。接着介绍了互调失真表征技术，分析了在单频音和多频音信号激励下的一些非线性失真特性，如AM-AM, AM-PM，谐波失真(HD)，互调失真(IMD)和邻近信号功率比(ACPR)等。其次从MOSFET功率放大器输入电压与输出电流之间的非线性传递函数出发，采用泰勒级数和分段近似相结合的方法，具体推导了双频音激励信号下的三阶互调失真(IMD3)解析表达式，
并将其算法仿真结果与通常的三阶幂级数模型分析结果以及ADS实验仿真结果做了对比，验证其正确性。最后依据CDMA信号经过功率放大器幂级数模型的频谱密度公式，导出了邻近信道功率比(ACPR)和载波互调失真比(IMR)之间的简易关系，并通过实测数据和ADS实验仿真结果进行了验证。
关键词功率放大器；互调失真；邻近信道功率比；双频音测试
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哈尔滨工业大学工学硕士学位论文
原油加热器Abstract
With the rapid development of wireless communication technology, human in order to make more efficient use of frequency spectrum and achieve higher data transmission rate, widely use linear modulation technology, such as QPSK and QAM and so on. These linear modulation signal with changing envelop, through non-linear RF power amplifier will produce intermodulation distortion, causing serious inter-symbol interference and adjacent-channel interference. The high linear power amplifier has to be used to guarantee communication quality. Unfortunately high linear power amplifier usually is inefficient. For solving this problem, we need to understand the non-linear charact
eristics of RF power amplifier, and not simply add external circuit to sacrifice efficiency for linear. On the other side, in order to guarantee the quality of communication, these are stringent figures of non-linear distortion in various wireless systems. Quantitative description of these figures is also very important to guide nonlinear system design.
This paper firstly present the nonlinear analysis basis of RF power amplifier, and detailed discussion the basic concepts ，theory and technology of nonlinear analysis, as well as summarize and compare various nonlinear technique. In order to introduce the harmonic balance technique, we use ADS simulation as an example. Then we introduce the intermodulation distortion characterization technology, and analysis some nonlinear characteristic excited with a one tone or multi-tone, such as AM-AM, harmonic distortion, intermodulation, adjacent-channel power ratio. Secondly, we study the input voltage/output current’s transfer function of MOSFET power amplifier, and adopt Taylor series and piecewise linear function combing method, with which we derive third-order intermodulation distortion’s analytical expression of two-tone signal exciting. In order to verify its correctness, we compare its results with normal third-order power series analysis results and ADS simulation results. Lastly based on spectrum density formula of CDMA signal passing through third-order power series model of power amplifier, we derive simplified relationship between the
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