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类型 基础研究 预答辩日期 2018-04-04
开始(开题)日期 2013-05-22 论文结束日期 2018-01-04
地点 逸夫科技馆北四楼403室 论文选题来源 非立项    论文字数 5.8 (万字)
题目 基于N型GaAs HBT工艺的1.5-2.7GHz差分推挽功率放大器的研究
主题词 砷化镓异质结双极型晶体管,功率放大器,推挽,差分
摘要 砷化镓异质结双极型晶体管(GaAs HBT)广泛应用于射频功率放大器的设计。功放是射频前端模块中耗能最多的器件之一,因此要求功放具有高效率的特点。推挽放大器的上、下两支路在一个射频信号周期内轮流导通,是一种常用的提高效率的电路结构。但是GaAs HBT互补推挽电路中,将P型和N型晶体管制作在同一个GaAs衬底上,由于最优电流密度的不同,限制了电路的功率处理能力;并且为了得到最佳性能,所需要的外延结构有很大区别,制作工艺复杂,成本很高。在传统的非互补推挽结构中,输入和输出端口均需要变压器或者无源巴伦,输入端是为了形成一对幅度相等、相位相反的输入信号,输出端则是为了反相合成上下支路晶体管集电极的输出信号。但是变压器和巴伦的物理尺寸比较大,不利于片上集成。 本文首先对基于N型GaAs HBT工艺的高效率、单端口输入和输出的非互补推挽射频功放进行了研究;然后基于上述研究结果,从差分电路结构、热分布优化技术、自适应线性化偏置技术、宽带匹配技术以及电路实现等方面对宽带、高效率、高线性的差分推挽射频功放展开研究。论文的主要研究工作和创新如下: (1)基于N型GaAs HBT工艺以及晶体管集电极和发射极输出信号反相的特性,改进了传统非互补推挽电路结构,提出了一种高效率、单端口输入和输出的推挽电路,输入和输出均不需要采用变压器或无源巴伦。仿真结果表明,工作频点为2.1GHz时,电路的功率增益为21dB,输出功率为32dBm,功率附加效率(PAE)为50%。此外,与传统共射极射频功放相比,输出功率相当的情况下,该电路结构的二次谐波分量减少了4.04dB,三次谐波分量减少了9.19dB,明显提高了功放的线性度。 (2)基于差分结构线性度的优势和两组同样的N型非互补推挽电路,提出了一种高线性的差分推挽电路结构,有效地减小了单组N型非互补推挽结构由于上下支路不对称性导致的输出波形正负半周的差异,同时提高了输出信号的摆幅。并且输入端利用HBT晶体管替代无源巴伦以减小版图面积。仿真结果表明:一款工作频段为1.8GHz-2.4GHz的差分推挽功放,单组推挽和差分推挽输出波形正负半周峰值的差异分别为1.49V和1.02V,差异分别占相应输出电压摆幅的15.38%和5.09%,改善了10.29%。 (3)提出了一种新型热分流结构,通过引入集电极金属,新增加一条热源到地的散热路径,改善功放的热分布,同时提高电路的PAE。相较于传统的热分布优化技术,该热分流结构可以针对性的降低基极-集电极结温度。仿真结果表明,功放正常工作时,温度分布达到稳态后,传统版图布局结构中HBT热源处温度最高为163℃,新结构为148℃,较传统结构下降了15℃,改善了9.2%,同时电路PAE提高了2%。 (4)综合上述研究工作,基于N型2μm GaAs HBT工艺设计并实现了一款工作频段为1.5GHz-2.7GHz的宽带、高效率、高线性差分推挽功率放大器:基于自适应线性化偏置技术电路增益提高了1dB;基于阶梯型行波传输匹配技术将电路带宽拓展至1.2GHz;基于差分推挽结构将输出波形差异改善了10.45%。芯片面积为0.9×1.5mm2,测试时在片外利用了一个传输线巴伦对推挽级输出波形进行合成。测试结果表明供电电压12V时,在1.78GHz-2.67GHz的频段内电路输入回波损耗S11低于-15dB;2.1GHz时小信号增益S21为27dB,输出功率P1dB为34dBm,PAE达到45%。 论文基于以上工作,实现的功率放大器在1.5GHz-2.7GHz频段内具有高效率、高线性、高功率的特点,可应用于北斗卫星定位、LTE、WLAN等多种通信系统。
英文题目 RESEARCH OF 1.5GHz -2.7GHz DIFFERENTIAL PUSH-PULL POWER AMPLIFIER BASED ON N-TYPE GaAs HBT
英文主题词 GaAs HBT,Power Amplifier,Push-pull,Differential
英文摘要 Gallium arsenide (GaAs) heterojunction bipolar transistor (HBT) is currently the technology of choice for radio frequency (RF) power amplifier (PA) due to its excellent RF performance. PA is one of the most energy consuming devices in RF front-end modules, and demands high efficiency. The push-pull (PP) configuration, whereby two transistors amplify alternative half cycles of the RF signal, is a basic building block for high efficiency applications. However, the NPN-PNP complementary GaAs HBT PP configuration is rarely employed in PA design. On a same GaAs substrate, the collector currents of the PNP and NPN HBTs are largely different due to the optimum current density differences. And it limited the power handling capability of the circuit. The PNP and NPN HBTs are rarely fabricated on the same chip for the great difference requirement in the epitaxial layer to achieve excellent performance. And it’s complex and expensive to fabricate on the same substrate. In the conventional non-complementary PP configuration, an input anti-phase splitter and output anti-phase combiner are usually required. These are often based on transformers or passive baluns. Both can be physically large, making them unsuitable for miniaturization or IC fabrication. First, a high efficiency N-type non-complementary PP PA based on GaAs HBT with single ended input and output (I/O) ports is studied. Then, based on the above study, a broadband differential-push-pull (DPP) PA with high efficiency and linearity is investigated, including the differential configuration, thermal distribution optimization technique, adaptive linearization bias technique, broadband matching technique and circuit implement methdology. Several creative works have been done in this dissertation: (1) Based on N-type GaAs HBT process and the inverted nature of the collector and emitter output signals of HBT, a non-complementary PP PA with single ended I/O ports and high efficiency is proposed. There are no needs of baluns at I/O port. The simulation results show that 32dBm P1dB (output power at 1dB compression point), 21dB power gain and 50% PAE (power added efficiency) are achieved at 2.1GHz. In addition, the second and third harmonic component of the proposed PA reduces 4.04dB and 9.19dB, respectively, compared with the traditional common emitter PA in the case of same level of Pout. (2) Based on the configuration of differential structure and two same PP stages, a DPP PA with high linearity is proposed to improve the swing and the symmetry of the output waveform of the non-complementary PP PA. To save the area of the layout, the input stage employs an active HBT instead of the passive balun. The simulation results show that, with the operating frequency of 1.8GHz to 2.4GHz, the differences between peak values of the positive and negative half cycle of the output are 1.02V and 1.49V, respectively, for the proposed DPP PA and the PP PA when working at 2.1GHz. The difference values account for 5.09% and 15.38% of the output voltage swing, respectively, with an improvement of 10.29%. (3) A novel type of thermal shunt structure in layout design is proposed to optimize the thermal distribution and improve PAE of PA. The proposed thermal shunt structure introduces collector metal to provide a new heat dissipation path from the power cells of the chip to the ground. It is specially designed to improve the thermal distribution of the base-collector (BC) junction. The simulation results show that, by adding this cooling path, the maximum temperature of the power cells is effectively reduced from 163°C to 148°C when the circuit is working normally, with an improvement of 9.2%. And the PAE is enhanced by 2%. (4) Based on the above methodologies and techniques, a 1.5GHz -2.7GHz DPP PA is implemented using 2μm N-type GaAs HBT process with broadband, high efficiency and linearity. The gain is improved by 1dB based on adaptive linearization bias technique. The bandwidth is expanded to 1.2GHz based on patered travelling wave input matching technique. The difference between peak values of output is improved by 10.45% based on the DPP strcture. The chip size is 0.9×1.5mm2. An off-chip transmission line Balun is used to combine the output signals of the two push-pull stages for measurment. The measurement results show the input return loss is better than 15dB from 1.78GHz to 2.67GHz. 34dBm P1dB, 27dB power gain and 45% PAE are achieved at 2.1GHz. Consequently, based on above works of this dissertation, high efficiency, high linearity and high power in 1.5GHz-2.7GHz broad operation frequcncy for DPP PA is realized. The proposed broadband PA can be applied in Beidou satellite, LTE and WLAN communication systems.
学术讨论
主办单位时间地点报告人报告主题
高频高功率实验室 2011.04.25 东南大学苏州研究院三江院一楼会议室 陈涛 射极电感对功放性能影响及应用
高频高功率实验室 2011.12.07 东南大学苏州研究院三江院一楼会议室 陈涛 功率放大器线性化方法
高频高功率实验室 2012.03.24 东南大学苏州研究院三江院一楼会议室 孙晓红 HBT建模及结温的计算
高频高功率实验室 2013.04.12 东南大学苏州研究院三江院一楼会议室 田婷 N型非互补推挽放大器设计
高频高功率实验室 2013.04.17 东南大学苏州研究院三江院一楼会议室 孙晓红 射频HBT功率放大器热效应研究
高频高功率实验室 2015.11.27 东南大学苏州研究院三江院一楼会议室 田婷 N型非互补差分-推挽放大器设计
高频高功率实验室 2016.11.17 东南大学苏州研究院三江院一楼会议室 田婷 New Thermal Shunt Structure
高频高功率实验室 2017.05.26 东南大学苏州研究院三江院一楼会议室 田婷 1.5GHz-2.7GHz N型GaAs HBT差分-推挽放大器设计
     
学术会议
会议名称时间地点本人报告本人报告题目
第八届中国微纳电子技术交流与学术研讨会 2015.07.29 成都,四川 一款采用热分流技术的30W大功率北斗功放模组
IEEE IAEAC 2017, Chongqing 2017.03.25 重庆 Thermal Design of Microwave Power Amplifiers Based on GaAs HBTs
     
代表作
论文名称
Thermal Design of Microwave Power Amplifiers Based on GaAs HBTs
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
陈军宁 正高 教授 博导 安徽大学 主任委员
吴宁 正高 教授 博导 南京航空航天大学
廖小平 正高 教授 博导 东南大学
吴建辉 正高 教授 博导 东南大学
张萌 副高 副教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
李红 其他 讲师 东南大学 秘书