【作者】 刘岩；

【导师】 周勇；

【作者基本信息】 上海交通大学 ， 电子科学与技术， 2016， 硕士

【摘要】 随着电子技术的发展,人们的生活中已经离不开各种电子设备,其中传感器是必不可少的组件。磁场在空间中无处不在,利用磁传感器可以实现航空航天、航海或是车载的导航,可以使用在工程材料的探伤,也可使用与医疗或是其他的科研方面。目前测量磁场的传感器主要有SQUID、霍尔传感器、GMR、核磁共振磁强计、磁通门传感器等,其中磁通门传感器作为pT级的室温高精度矢量磁传感器,已经在性能和体积方面有了巨大提升,在国防、社会和经济领域有着广泛的应用。近年来,磁通门传感器的小型化,尤其是利用MEMS技术的微型化集成磁通门传感器是磁通门传感器的主要研究方向。它的出现,解决了传统工艺制作的传感器笨重,使用困难,不方便携带等诸多缺点,并且能够与CMOS电路相集成。由于MEMS磁通门传感器由于工艺问题,感应线圈的多层紧密缠绕很难实现,但是相比于传统磁通门传感器,MEMS磁通门传感器的磁芯可以做的更薄,使用磁导率较高的非晶纳米晶软磁薄膜磁芯可以将激励频率做到数百千赫兹或上兆赫兹,可以有效的提高微型化磁通门传感器的性能。所以本文基于这个特点,设计了一种基于FPGA的高频率、微小信号测量的磁通门工作电路。本文首先列举了磁场的检测方法,对磁通门传感器的历史,工作原理和检测微弱信号的方法做了论述,其后论述电路的设计思路,在信号激励方面,选用合适的芯片,制作了信号发生器,缓冲器,功率放大电路,并对前端激励末尾部分的隔直流模块的优点通过测量数据进行说明。在感应信号处理方面,论述了信号放大器,AD转换电路的实现,并针对基于FPGA的正交矢量锁相放大电路的设计思路和每步设计步骤进行说明。在上述设计中利用Multisim,Quartus II,Modelsim软件对波形和信号处理进行了仿真,并测试了部分电路使用过程中的实际波形。最后,本文基于这套电路和所制作的磁屏蔽装置和磁场产生装置,对一种MEMS磁通门传感器的测量范围,灵敏度,线性度和精度进行了测量,对整体测量性能进行评价,验证了整个系统的可行性。本文设计的测量系统与其他测量系统相比:(1)相对于传统磁通门传感器的模拟电路信号处理,使用FPGA数字信号处理抗干扰能力更强。(2)通过一片FPGA实现数字信号处理,较一般的电路中使用FPGA和ARM配合处理的成本更低,提高电路的集成度。(3)使用方便,方便携带及改进。基于MEMS磁通门传感器的工作特点,本文设计了一种传感器工作电路,相对于传统磁通门传感器更加微型化、数字化,系统使用性能较好,可以用于一般情况下的磁场测试。更多还原

【Abstract】 With the development of electronic technology,human have been inseparable from a variety of electronic devices.Sensors are essential components in these devices.Magnetic field is existing in everywhere,so the detection of magnetic field have a wide application in various aspects such as navigation of aerospace,marine and automotive,engineering materials testing,medical and other scientific research.Currently,there are many magnetic sensors such as SQUID,Hall,GMR,nuclear magnetic resonance,fluxgate.As a pT level high-precision vector magnetic sensor,fluxgate has triggered numerous promising in fields of national defense,society and economic due to their improved performance and volume.In recent years,fluxgate miniaturization is becoming the main research hot-spots,especially miniaturizing by micro electro mechanical system technology.Miniaturization of fluxgate can overcome the defect such as bulky in use,difficult in carry of the conventional fluxgate.Moreover,the miniaturized fluxgate can be integrated with the circuits.Due to the micro-fabrication limits,it is hard to realize more than 2 layer 3D coils of MEMS fluxgate.However,comparing with conventional fluxgate sensor,magnetic core of MEMS fluxgate can be miniaturized and more thinner by micro fabrication technology.when the fluxgate core make use of amorphous and nanocrystalline soft magnetic thin film,the frequency of excitation current was enhanced,the non-ideal effects was reduced.In consideration of these challenges,designing a circuit based on analog circuit and FPGA for MEMS fluxgate using in weak signal measurement is great needed.Firstly,we enumerate the present detection methods of magnetic field,and then elaborate the history,working principle,and weak signal measuring method of fluxgate sensor.Next,we will discuss the design of MEMS fluxgate circuit including signal generator,buffer,power amplifier and DC blocking.And we also investigate the characters of using DC blocking by analyzing the measurement data.In signal processing,we discuss signal amplifier,AD converter,and FPGA circuit which is used as the orthogonal vector phase-locked amplifier.Multisim,Quartus II,Modelsim are employed in simulating the waveforms and comparing to the actual waveforms.Finally,we test a MEMS fluxgate and evaluate the feasibility of the entire system.Comparing with other measurement circuits:(1)Digital signal processing based on FPGA has better antijamming capability than analog signal.(2)Lower cost and higher integration than other circuits based on FPGA and ARM.(3)Convenient to use and carry.Based on the working characteristics of MEMS fluxgate sensor,the operating circuit was designed.Comparing with conventional fluxgate sensor,MEMS fluxgate is more miniaturization,digitization and possess better measuring performance.So,it can be used in general magnetic measurement.更多还原