【作者】 阮颖；

【导师】 赖宗声；

【作者基本信息】 华东师范大学 ， 微电子学与固体电子学， 2012， 博士

【摘要】 功率放大器是无线发射机重要的射频前端模块,也是消耗能量最大的部件。现代无线通信系统通常需要采用高峰均值的调制信号提高信道容量和传输速率,同时电池寿命是影响移动便携式设备使用的关键因素之一。在无线通信设备低成本、小体积、低功耗的需求推动下,单芯片全集成的功率放大器应运而生。在早期射频集成功率放大器(RFIC PA)中,以GaAs/InP基片材料为代表的Ⅲ-Ⅴ族功率放大器完全处于统治地位,但该类功放难以与基带等其它电路集成。近年来,随着CMOS工艺的日益成熟和SiGe外延技术水平的不断提高,SiGe BiCMOS器件的截止频率、工作电压和功率密度等均得到了显著改善。而为了进一步提高射频通信系统芯片的兼容性、降低系统成本,满足多模式多频段应用需求,更使SiGe BiCMOS RFIC PA技术得到业界的广泛关注而成为研究热点。本文的研究工作是基于国内某新建的0.18umSiGe BiCMOS工艺线开展的。首先对工艺线进行了功率器件开发和建模,完善该工艺的功率单元模型和PDK数据包；以此为基础,对可用于无线局域网的功率放大器进行了关键技术研究和流片验证。本文取得的主要成果如下：1)针对无线局域网功放的应用要求,提出了四种不同结构的功率单元(Power Cell)设计。基于Volterra级数分析了主要功率器件SiGe HBT的非线性等效电路和功率单元的热平衡布局,对在大信号条件下各种高频谐波非线性参数对功放的影响进行比较和评估,对不同结构的功率单元进行DC和RF测试,提供了Power Cell模型库的关键数据,为无线局域网的功放设计奠定了技术基础。2)基于SiGe HBT器件的自加热效应分析和比较基极镇流和射极镇流这两种功放热稳定性设计,提出了一种在基极偏置中实现温度稳定性的电路结构,其特点是在功率晶体管基极的DC通路中采用电阻和电容并联,从而降低基极镇流电阻对功率增益的影响,以较小的直流功耗和射频损耗而有效的防止热击穿。3)研究功放中重要结构单元—键合线的射频特性对于功放性能的影响。针对键合互联线不同的结构参数,用高频三维电磁仿真软件HFSS构建三维物理模型,采用有限元方法进行全波分析。建立键合线的π型等效电路,提取在不同物理模型下金丝键合线的R、C、L等效参数,PCB键合测试获得了多种结构金线的射频插损。4)针对无线局域网802.1lb/g协议的要求,采用集成二极管负反馈动态偏置技术,设计了PA线性化和温度稳定的偏置电路,实现了一种包括了匹配电路、放大电路和偏置电路的单芯片全集成2.4GHz功放。测试结果表明,其功率增益为22dB,输出1dB点功率为19.6dBm,功率附加效率为20%。5)针对WLAN2.4GHz/5GHz双频段应用要求,实现了一种单端共射极三级级联双频段功放。设计了一种对功放偏置静态电流进行调控和阻抗可变的变容二极管自适应偏置电路,降低了PA的直流功耗,提高了输出1dB压缩点功率。测试结果表明,在2.4GHz频率下,其功率增益达27.1dB,OP1dB达25.5dBm, PAE达26.1%；在5.25GHz频率下,功率增益为22dB, OP1dB为21.1dBm, PAE为20.2%。本文受核高基国家重大专项《嵌入式多模、多频收发器关键IP硬核研究》(编号：2009ZX01034-002-002-001)和上海市国际科技合作基金项目《锗硅BiCMOS射频前端关键集成电路设计技术研究》(编号：09700713800)资助。更多还原

【Abstract】 PA is the most important RF front-end module and the largest energy consumer among all the components in wireless communication systems.High peak-to-average ratio(PAR) complex modulation signal is usually demanded in modern wireless communication systems to improve the channel capacity and transmission rate. Also battery life is a key factor for the utility of portable devices. Driven by the demands of lower cost, smaller size and lower power consumption, the fully integrated PA emerges.In the initial years for radio frequency power amplifier (RPIC PA), PAs based on GaAs/Inp III-V material are completely dominant. But these PAs are hard to be integrated with other circuit in a single chip. In recent years, SiGe BiCMOS technology has got gradual improvement in device’s cutoff frequency, working voltage and power density, because the CMOS process has been more mature and SiGe epitaxy technology has improved greatly. To reduce RF system cost, improve its compatibility for the demanding of multi-mode and multi-band applications, SiGe BiCMOS RFIC PA achieves more and more attention and becomes a hot pot.The research work is based on the newly-built0.18um SiGe BiCMOS process in China. In this dissertation, the modeling of power cell and the PDK data are improved firstly. Then two samples of2.4GHz and5GHz PAs for Wireless-LAN application are studied and verified in the domestic SiGe BiCMOS process. The main work attributions of this thesis are as follows:1) Four kinds of power cell are proposed for the demanding of PAs for Wireless-LAN applications. SiGe HBT nonlinear equivalent circuit is analyzed according to Volterra series and power cell layout are thermally optimized. The effects of harmonic nonlinearity parameter are evaluated. Also the power cells are tested under both DC and RF condition, The measurement results also provide the critical data of the power cell library and lay the technical foundation for PA design.2) A new temperature stabilization design is proposed in the PA’s base biasing path based on the comparison of base-ballasting and emitter-ballasting methods. The design is comprised of parallel resistor and capacitor, preventing thermal runaway effectively and almost causing no insert loss or RF power penalty.3) The effect of bondwire upon PA is assessed.Three-dimensional physical models of bondwire are built in HFSS and analyzed by the finite element method. Equivalent circuit is established and parameter is extracted in different physical models. The insert loss of serveral bondwire is evaluated by testing on PCB.4) A fully-integrated2.4GHz PA is implemented which includes all the matching, biasing and power circuits for the demanding of Wireless-LAN802.11b/g protocol. With the diode-based negative feedback dynamic biasing technique, a linearization and temperature-stable bias circuit is proposed. The measurement results show that the PA has a power gain of22dB, OP,dB of19.6dBm and PAE of20%.5) A dual-band PA with3-stage single-ended common-emitter topology is designed for supporting both2.4GHz and5GHz WLAN applications. A varactor-based adaptive biasing circuit with regulating bias current function is designed, which reduces the average DC power consumption of PA and improves its output1dB power. The test results indicate that the PA achieves a power gain of27.2dB, OP1dB of25.5dBm and PAE of26.1%in the2.4GHz band and a power gain of22dB, OP1dB of21.1dBm and PAE of20.2%in the5GHz band.This dissertation work is supported by the National key project "Core Electronic Devices, High-end General Chips and Basic Software", subtitle of,"Embedded Multi-mode, Multi-band Transceiver Hard Core of Key IP"(No.2009ZX01034-002-002-001) and Shanghai International Cooperation Foundation,"SiGe BiCMOS RF front-end Design of Key Integrated Circuits"(No.09700713800)更多还原