Design On MEMS Fluxgate Sensor Circuit And FPGA Signal Process

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.