吳安宇臺灣大學：電子工程學研究所陳圓覺Chen, Yuan-JyueYuan-JyueChen2007-11-272018-07-102007-11-272018-07-102007http://ntur.lib.ntu.edu.tw//handle/246246/57492在現今的無線通訊系統中，功率放大器是最消耗功率的元件。而功率放大器又具有非線性特性，因此要設計高效率又高線性度的無線發射機便成了一個相當困難的挑戰。於是多種不同功率放大器的線性化技術被採用來改善無線發射機的線性度及效率。 在這些線性化的技術中，LINC技術可以使用高效率的非線性功率放大器而且可達成線性放大。除此之外，數位信號處理在CMOS製程下具有相對的低成本及其不易受製程變易影響的特性，因此數位化的LINC架構特別適用於當今的製程。 當LINC提高功率放大器效率的同時，LINC需要一個額外的功率合成器來達成線性放大。然而這個低效率的功率合成器會導致整個無線發射機的效率大幅降低。為了改善功率合成器的效率，且同時達到高效率的功率放大器，我們提出了一個多階級系統。基於這個多階級系統，我們提出兩種不同的線性化架構: 增益調整多階級LINC(Gain-adjusting multilevel LINC, GA-MLINC)及包絡調整多階級LINC(Envelope-adjusting multilevel LINC, EA-MLINC)。在WCDMA系統線性度的要求下，三階的增益調整多階級LINC及三階的包絡調整多階級LINC分別可改善LINC系統的輔助功率從16.5%到23.6%及33.4%。Power amplifiers (PAs) are the most power-hungry devices in modern wireless communication systems. Designing a high linearity and high power efficiency wireless transmitter is a big challenge due to the nonlinear characteristic of the power amplifier. Various PA linearization techniques have been adopted to improve linearity and power efficiency of wireless transmitters. Among them, the linear amplification with nonlinear components (LINC) technique can use high-efficiency nonlinear PAs and achieve a linear amplification. In addition, digital signal processing is widely available at a relatively low cost in nowadays CMOS technology and insensitivity to process variation. Thus, the digital LINC architecture is more suitable for modern process technologies. While LINC increases the efficiency of power amplifiers, LINC requires an extra power combiner to obtain the linearly amplified signal. This low-efficiency power combiner results in low system power efficiency of wireless transmitters. To not only increase power combiner efficiency but also achieve high PA efficiency, we propose a multilevel out-phasing (MOP) scheme and two architectures: gain-adjusting multilevel LINC (GA-MLINC) and envelope-adjusting multilevel LINC (EA-MLINC). Under WCDMA linearity requirements, 3-level GA-MLINC and 3-level EA-MLINC enhance the LINC system power-added efficiency from 16.5% to 23.6% and 33.4%, respectively.Chapter 1 Introduction 1 1.1 Motivation and Goal 1 1.2 Approach 2 1.3 Organization 3 Chapter 2 PA Linearization Techniques Overview 5 2.1 Characteristic of Power amplifier 5 2.1.1 Behavior of an Ideal Linear PA 5 2.1.2 Square Law and Third Order Characteristic of PA 5 2.1.3 Saleh Model 8 2.1.4 Varying Envelope and Constant Envelope Input Signals 9 2.2 Methods of Power Amplifier Linearization 11 2.2.1 Feedback Architecture 11 2.2.2 Feedfordward Architecture 12 2.2.3 Predistortion Architecture 13 2.2.4 Envelope Elimination Restoration 14 2.2.5 Linear Amplification with Nonlinear Components 16 Chapter 3 LINC Transmitter System Overview 19 3.1 LINC Overview 19 3.1.1 Phase Modulation Method 21 3.1.2 I/Q Modulation Method 22 3.2 Review of the system architecture of LINC 22 3.2.1 Conventional Analog LINC Architecture 22 3.2.2 In Phase / Quardrature Method Architecture 24 3.2.3 Digital IF with Image Rejection 25 3.3 System Efficiency of LINC Transmitter 26 2.3.1 LINC System Efficiency 26 3.3.2 LINC System Power Added Efficiency 27 3.4 Power Combiners for LINC Transmitter 27 3.4.1 Lossy Combiners 28 3.4.2 Lossless Combiners 28 Chapter 4 Multilevel Out-Phasing Scheme 29 4.1 Out-phasing Technique 29 4.2 Multilevel Scaling Technique 31 4.2.1 Optimal Scale Factor Determination 32 4.3 Multilevel Linearization Technique 34 Chapter 5 Multilevel LINC Architectures 39 5.1 Multilevel Signal Component Separator 39 5.2 Gain-Adjusting MLINC 39 5.2.1 Gain-Adjusting Technique 39 5.2.2 GA-MLINC Architecture 40 5.3 Envelope-Adjusting MLINC 43 5.3.1 Envelope-Adjusting Technique 43 5.3.2 EA-MLINC Architecture 44 Chapter 6 LINC System Simulations and Comparisons 47 6.1 System Specification of WCDMA Transmitter System 47 6.1.1 Error Vector magnitude 47 6.1.2 Spectrum Emission Mask 48 6.1.3 Adjacent Channel Leakage Power Ratio 49 6.2 Combiner Efficiency 51 6.3 System Simulation Results of LINC 53 6.3.1 System Output Power Comparison 53 6.3.2 System PAE Comparison 53 6.3.3 Linearity Comparison 55 6.3.4 Linear Region Comparison 56 6.3.5 Performance Comparison 58 Chapter 7 Conclusions and Future Work 59 7.1 Conclusions 59 7.2 Future Work 60 References 61 Appendix 641183313 bytesapplication/pdfen-US功率放大器功率線性化LINCPApower efficiencythesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/57492/1/ntu-96-R94943014-1.pdf