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类型 基础研究 预答辩日期 2018-05-04
开始(开题)日期 2015-12-21 论文结束日期 2018-01-22
地点 李文正楼北412 论文选题来源 省(自治区、直辖市)项目    论文字数 5.03 (万字)
题目 基于深亚微米CMOS工艺 射频光传输系统的研究
主题词 ROF,激光器,预失真技术,光电探测器,PGA
摘要 随着人类对信息传输速率的要求越来越高,现有的频段已经不能满足人们的需求,因此研究者将目光开始放到了更高的频段。但是,高频信号因为高损耗的问题很难实现长距离传输。为了解决这个问题,结合了光纤通信与无线通信两者优势的射频光传输即ROF(Radio over Fiber)技术获得了广泛的关注。ROF系统是未来高速宽带无线通信中一个重要的组成部分,具有广阔的应用前景。 本文针对ROF系统的各个模块进行了分析和研究,主要的工作如下: 1) 对ROF系统的增益特性、噪声特性与非线性特性进行了系统的理论研究。研究表明,可通过无耗匹配网络、减小驱动源输出阻抗;可选用小寄生电阻的激光二极管(LD)减小发送端匹配损耗;可通过无耗匹配网络、增大前置接收放大电路输入阻抗;并可选用小导纳PD减小接收端匹配损耗。另外,射频信号损耗与光传输链路损耗的平方成正比,即光路1dB损耗将产生2dB射频损耗。因此,光路损耗需要仔细设计。(2)通过研究ROF系统的噪声特性,导出了在PD输出端噪声电流及系统噪声指数理论表达式,分析了ROF系统噪声指数与发送端匹配、LD直流偏置、光路损耗、接收端匹配、前置接收放大电路噪声特性的关系。实验研究了系统信噪比随LD直流偏置的变化曲线。研究表明,可通过无耗匹配网络、减小射频调制驱动器的输出阻抗、选用低阻值的LD可减小发送端匹配噪声;系统噪声指数随LD直流偏置的二次方增长。在满足其它条件的情况下,尽可能降低LD的直流偏置点;在接收端可通过采用无耗匹配网络、选用小跨导及小暗电流的PD、设计或选用低噪声前置放大器来改善接收端噪声性能。 2) 采用ADS(Advanced Designed Systems)软件里的SDD(Symbolic Defined Device)器件对激光器的物理模型进行了建模。激光器的模型对于设计ROF链路有着非常重要的意义。此外,根据激光器的速率方程,对激光器的大信号和小信号模型进行了分析。利用Volterra级数建立了激光器的数学模型,并进行了相关非线性公式的推导。 3) 独创地提出了一种全新的预失真电路,并通过TSMC 0.18?m CMOS工艺流片进行了验证。虽然针对ROF激光器的预失真技术已经有很多报道,但是最近30年,采用CMOS工艺设计的模拟预失真的电路却非常少。因为如果采用CMOS工艺,并按照传统的预失真结构来设计预失真电路,整体电路的结构是非常复杂的,而且需要占用很大的芯片面积,消耗更大的功率。这对于系统集成以及设计成本来说,是难以接受的。而本文提出的这个预失真电路具有结构简单、功耗低以及芯片面积小的优势,并且解决了预失真电路不能实现宽带工作的问题,实现了CMOS模拟预失真技术的突破。测量的结果表明IMD3在1~2.5GHz的工作带宽下,IMD3有3~16dBc的下降。 4) 提出了DNW-strip-SMPD和Psub-strip-SMPD两种结构的光电探测器。基于对光电探测器的工作原理以及性能指标的研究,对SMPD结构的光电探测器建立了数学模型分析,并用Matlab软件对3dB带宽与PN结之间距离的关系进行了仿真。通过SILVACO软件对两种能够有效提高光电探测器带宽的结构进行了器件仿真,为CMOS光电探测器的设计提供了依据。本次设计的光电探测器的测试结果显示DNW-strip-SMPD的工作带宽为2.9GHz,而Psub-strip-SMPD的工作带宽为1.8GHz。此外,DNW-strip-SMPD和Psub-strip-SMPD的寄生电容的值大约为820fF和440fF。Psub-strip-SMPD 在响应度和寄生电容方面具有优势,而DNW-strip-SMPD 则是在带宽方面具有优势。 5) 提出了一种应用于射频光传输链路的宽带可编程增益放大器(PGA),通过数字控制晶体管的有效宽长比来实现增益的可变。测试结果表明宽带PGA的3dB带宽为0.9~5GHz,实际测试的增益步长接近3dB。在最高增益的工作状态,测得最小噪声系数为4.7dB,而在最低增益工作状态,最小噪声系数为8.5dB。在最大增益模式下的IIP3大小为-9.6dBm。
英文题目 Research of Radio over Fiber Systems in Deep Submicron CMOS Technology
英文主题词 ROF,laser,predistortion technology,photodetector,PGA
英文摘要 With the increasing demand for high information transmission rates, the existing frequency bands can no longer meet people’s needs, so researchers are starting to put the vision in the higher frequency band. However, a high frequency signal is difficult to achieve long distance transmission because of the high medium loss. In order to solve this problem, ROF (Radio over Fiber) technology, which combines the advantages of optical fiber communication and wireless communication, has attracted wide attention. ROF will be an important technique of high speed broadband wireless communication in the future, and has a broad application prospect. Therefore, each module of the ROF system is analyzed and studied in this dissertation. The main works are as follows: 1) The gain, noise and nonlinearity of ROF systems are analytically studied. The results show that using lossless matching network and reducing output resistor of the driver and the resistance of the laser diode can reduce the match loss of the transmitter. For the receiver, using a lossless match network, increasing the input resistor of the preamplifier can decrease the matching loss. In addition, the RF loss increases with the square of the optical loss, that is, 1dB of optical loss deduces 2dB RF loss. Second, the noise current and noise figure theoretical expression of the ROF and the relationship of the matching of the transmitter, laser bias current, optical loss, the matching of receiver, the noise properties of the preamplifier and the system noise figure are obtained. The curve of system SNR (signal to noise ratio) vs laser bias current is experimentally studied. The results show that by using lossless match network and reducing the output resistance of the driver and the series resistance of the laser, matching noise of the transmitter can be decreased, because the NF (noise figure) increases with the laser bias current, system noise can be decreased with the laser bias current reduction. For the receiver, the matching noise of receiver can be decreased by using a lossless match network, increasing the input resistor of preamplifier, reducing the conductance of the photon diode, and designing a low-noise preamplifier. 2) The SDD (Symbolic Defined Device) in ADS (Advanced Designed Systems) software is used to form the physical model of the laser. The model of lasers is very important for the design of a RoF link. By using the rate equation of lasers, the large signal and small signal models are analyzed. The mathematical model of the laser is established by using the Volterra series, and the derivation of the related nonlinear formula is also carried out. 3) A novel CMOS analogue broadband pre-distortion circuit fabricated in a 0.18-μm CMOS technology is firstly presented. Although there have been many reports about the predistortion technology for ROF lasers, but in recent 30 years, the analog predistortion circuit designed by CMOS technology is very few. If the predistortion circuit is designed in CMOS technology, and in accordance with the traditional predistortion structure, the whole circuit structure will be very complex, and it also needs a large chip area and consumes a large power. It cannot be tolerated with the system integration and the cost. The pre-distortion circuit proposed has the advantages of a simple structure, a low power consumption, and a small chip area. The problem that the predistortion circuit can not operate in broadband is solved. It realizes the breakthrough of CMOS analog predistortion technology for ROF systems. The measured results suggest that IMD3 has 3~16 dBc reduction over 1~2.5 GHz. 4) DNW-strip-SMPD and Psub-strip-SMPD are proposed. With the research of the photodetector’s working principle and performance index, a mathematical model analysis for the photodetector of the SMPD structure is established. Matlab is used to simulate the relationship between the 3-dB bandwidth and the PN junction distance. Two kinds of structure which can effectively improve the bandwidth of the photodetector are simulated by SILVACO software, which provides a basis for the design of CMOS photodetectors. The test results show that the working frequency of the DNW-strip-SMPD is 2.9 GHz while the Psub-strip-SMPD’s is 1.8 GHz. In addition, the parasitic capacitances of the DNW-strip-SMPD and Psub-strip-SMPD are around 820 fF and 440 fF, respectively. Psub-strip-SMPD has an advantage over the responsivity and parasitic capacitance, while DNW-strip-SMPD has better performance in 3-dB bandwidth. 5) A broadband programmable gain amplifier (PGA) for ROF links is proposed. The gain is variable by digital controlling the effective width and length ratio of the transistor. The test result shows that the 3-dB bandwidth of the broadband PGA is 0.9~5 GHz. The gain step is nearly 3 dB. At the highest gain, the minimum NF is 4.7 dB, while the minimum NF is 8.5 dB in the low gain mode. The IIP3 in the maximum gain mode is -9.6 dBm.
学术讨论
主办单位时间地点报告人报告主题
东南大学射光所 2017.11.20 射光所会议室 范忱 半导体激光器模拟预失真电路流片报告
东南大学射光所 2015.6.18 射光所会议室 范忱 光电探测器与TIA的设计与实现
东南大学射光所 2015.6.18 射光所会议室 范忱 3-9GHz低噪声放大器设计
东南大学射光所 2015.6.18 射光所会议室 范忱 TIA的设计与实现
东南大学射光所 2015.3.8 射光所会议室 马力 AGC电路设计
东南大学射光所 2014.12.29 射光所会议室 王俊椋 压控振荡器流片报告
东南大学射光所 2014.12.29 射光所会议室 王俊椋 正交分频器流片报告
东南大学射光所 2015.3.8 射光所会议室 马力 WBMIXER电路设计
东南大学射光所 2015.4.22 射光所会议室 吴毅强 DRM/DAB项目总结报告
     
学术会议
会议名称时间地点本人报告本人报告题目
Progress in Electromagnetic Research Symposium 2017.5.25 Park Inn by Radisson Pribaltiyskaya hotel,Saint Petersburg ,Russia Design of a Wideband CMOS Variable-Gain Low Noise Amplifier
Progress in Electromagnetic Research Symposium 2016.8.8 Shanghai International Convention Center,China A Novel Analog Broadband RF Predistortion Circuit in Directly Modulated Laser
     
代表作
论文名称
Acompactlowpowerconsumption 5Gbps OEIC receiver without equalizer fabricated in0.18μmCMOS technology
A Novel Pre-Distortion Circuit of Lasers Fabricated in 0.18-μm CMOS Technology
A Novel Analog Broadband RF Predistortion Circuit in Directly Modulated Lasers for Radio-over-fiber
 
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
陈鹤鸣 正高 教授 博导 南京邮电大学
乔庐峰 正高 教授 博导 南京解放军理工大学
胡庆生 正高 教授 博导 东南大学
李智群 正高 博导 东南大学
李文渊 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
王蓉 副高 副教授 东南大学