基于扇形MAGFET同步取样模式的CMOS磁敏传感器集成电路

研究了基于扇形MAGFET同步取样模式的CMOS磁敏传感器集成电路,并由0.6μm CMOS工艺实现.该CMOS磁敏传感器集成电路以共源极的扇形分裂漏磁敏MOS管作为磁敏传感单元,使磁敏传感器在参考工作模式和测量工作模式下实现同步取样,测量垂直磁场的同时,实现了在屏蔽磁场的参考工作模式下对磁敏传感信号进行噪声校正的功能.经过集成电路芯片的测试验证,同步取样模式具有较好的噪声校正功能,工作频率为20 kHz时,磁敏传感器的灵敏度为2.62 V/T.     

“磁传感器及其应用技术”讲座 第五讲 磁敏电阻传感器(二)

上一讲介绍了半导体磁敏电阻及强磁性金属薄膜磁敏电阻的结构、工作原理和特性。本讲将着重介绍这两种器件组成的各类磁传感器的具体应用。一、位移测量 1.半导体磁敏电阻构成的位移传感器利用磁场外磁敏电阻的相对位移所引起磁敏电阻值的变化可精确地检测位移。图1所示的磁变阻器是由磁钢和半导体磁敏电阻构成的一种结构简单的位移传感器。图中所用的半导体磁敏电阻具有带狭缝的匚型结构。并将其固定,磁钢采用等强度的均匀磁钢,当磁钢如图向右移动X时,由于半导体磁敏电阻感受到感应强度增大,其阻值也会相应的增加。此种磁变阻器具有位移传感器的特性,即R(X)/R(l)和X=b/l的关系如图1所示。这     

应用磁敏Z元件直流无刷电机电子换相电路的研究

对磁敏Z元件的基本伏安特性、磁敏特性进行了实验测试,给出了实验结果,从内在微观结构和导电机理上对磁敏Z元件的特殊性质进行了分析.利用磁敏Z元件的特性,设计了用磁敏Z元件作位置传感器的直流无刷电机的电子换相电路,实现了在磁敏Z元件采集到的正弦信号驱动下对四个绕组有序选通的控制,并针对Z元件输出信号随温度漂移的现象进行了测试分析.     

强磁性金属薄膜磁敏电阻的特点与应用

一、前言强磁性金属薄膜磁敏电阻是一种磁敏传感元件.该元件不仅对磁场强度敏感,而且对磁场方向也非常敏感.这种磁敏传感元件具有灵敏度高、温度特性好、坚固耐用、应用范围广等优点.强磁性金属薄膜磁敏电阻,在国际上还是70年代中期刚刚问世的     

YBa_2Cu_3O_(7-y)的磁敏特性

本文使用YBa_2Cu_3O_(7-y)块试制了高T_c超导磁敏元件.研究了电极对磁敏元件输出的影响,及液氮温区磁敏元件的输出电压与磁场的关系.研究结果表明高T_c超导磁敏元件在弱磁场下有较高的灵敏度,有可能在弱磁场检测方面得到应用.     

InSb-In共晶体薄膜磁阻式齿轮转速传感器

介绍一种用锑化铟—铟 (InSb In)共晶体薄膜磁敏电阻 (MR)制成的齿轮转速传感器 (GVS) ,它由磁敏电阻器和信号处理电路两部分构成。磁敏电阻器的噪声约为 95 μV ,磁敏电阻器与齿轮的距离为5mm时 ,输出信号约为 3mV ,信噪比约 30dB ,测量的准确性可与国外同类产品相媲美。     

三轴磁敏传感器误差分析与校正研究

三轴磁敏传感器被广泛应用于空间磁场测量。但由于非正交性、各通道定标比例系数的不一致性以及各通道零点偏置,三轴磁敏传感器不同的姿态会导致测量结果上的差异,即存在转向误差。首先对三轴磁敏传感器转向误差进行了细致的分析与计算,提出了一种轴间正交化、调整灵敏度和减小零点漂移的转向误差模型。然后,建立了与之对应的神经网络结构以实现对转向误差模型参数的智能辨识。最后,通过建立的误差模型实现了对转向误差的自校正。实验结果表明,所提的自校正方法能有效改善三轴磁敏传感器的性能。     

三漏CMOS磁敏器件

采用矩形结构的霍尔元件作为磁敏电路中敏感部分的硅霍尔磁敏器件已相当成熟,但磁灵敏度不大,仅约10~2V/AT.因此探讨具有高灵敏度的磁敏器件,对于工艺相当成熟的硅材料来说仍然很有意义.从硅的MOS器件来看,早先由Gallagher和Corak提出用MOS表面的反型导电层做MOS霍尔元件,曾达到10~3V/AT的灵敏度.而后由Fry和Hoey提出用双漏MOS场效应晶体管做成灵敏度达10~4V/AT的磁敏元件.由于负载电阻大,稳定性较差,Popovic和Baltes又进一步用这种晶体管做成CMOS差分放大器结构形式,得到了有同样灵敏度且较稳定的磁敏器件.     

磁敏生物传感器及其在生物检测中的应用

磁敏生物传感器是一种利用磁与电之间的关系对磁标记待测生物分子敏感,并将其磁信号转换为可用输出信号实现生物分子检测的新型传感器.对磁敏生物传感器及其在生物检测中的应用进行了综述,并对该领域的发展方向进行了展望.     

“磁传感器及其应用技术”讲座：第八讲 磁敏晶体管传感器（二）

二、磁敏三极管磁敏三极管是继磁敏二极管后出现的一种新型的三端结型元件。它分为PNP型和NPN型两种。所用符号同晶体三极管只在旁边加一磁场符号×以示磁敏三极管。目前国内已有这种器件的生产,其中3CCM型硅磁敏三极管的主要参数见表3。3BCM型锗磁敏三极管的主要参数见表4,把两只3CCM型磁敏三极     

Ferroelectric neuron circuits with adaptive-learning function

A neon circuit which consists of nonvolatile metal-ferroelectric-semiconductor field effect transistors (MFSFETs) and a uni-junction transistor (UJT) has been proposed. In the proposed circuit MFSFETs act as analog memories to store the synaptic weights which can be changed by the adaptive-learning process during the operations. In this paper, we first simulate the operation of the ferroelectric neuron circuit using a circuit simulator, SPICE. It is shown that the output frequency of the proposed neuron circuit can be changed after it processes a certain number of input pulses. Then, we report the fabrication of UJTs and UJT pulse oscillation circuits using silicon-on-insulator (SOI) substrates. It is found that the output frequency increases with decreasing the charging time of the capacitor in the circuit and that the operation at higher frequencies is possible for integrated UJT oscillation circuits. Finally, we demonstrate the memory and learning properties of n-channel ferroelectric-gate FETs using (Pb,La)(Zr,Ti)O₃ (PLZT) films. It is shown that the drain current of the PLZT/SrTiO₃/Si FETs can be controlled by a “write” pulse before the measurements.     

The effect of temperature and magnetic field on a quantum rod qubit

The Hamiltonian of a quantum rod (QR) with an ellipsoidal boundary is given after a coordinate transformation, which changes the ellipsoidal boundary into a spherical one. We obtain the eigenenergies and eigenfunctions of the ground and the first excited states of an electron, which is strongly coupled to the LO-phonon in a QR under an applied magnetic field by using the Pekar variational method. This system in QR may be employed as a two-level qubit. When the electron is in the superposition state of the ground and the first-excited states, we study the time evolution of the electron probability density. The relations of the probability density of electron on the temperature and the relations of the period of oscillation on the temperature and the cyclotron frequency of magnetic field are taken into consideration. The results show that the probability density of the electron oscillates in the QR with a oscillation period. It is found that the electron probability density and the oscillation period increase (decrease) with increasing temperature in lower (higher) temperature regime. The electron probability density increases (decreases) with increasing cyclotron frequency when the temperature is lower (higher). The oscillation period decreases with the increase of the cyclotron frequency.     

Dynamic behaviour of a magnetically actuated floating liquid marble

This paper reports the dynamic behaviour of a magnetically actuated floating liquid marble by analysing the oscillation of the marble. A liquid marble is a liquid droplet coated with hydrophobic powder. Magnetite particles inside the marble make it magnetic. The marble floats on a carrier liquid that contains aqueous glycerol of various concentrations. A permanent magnet located under the carrier liquid drives the floating marble with the initial velocity. Stopping the magnet abruptly causes the marble to oscillate around its final position for a few seconds. The oscillation was recorded and analysed using customised image processing and evaluation software. The damped harmonic motion model was then applied to the data and tested. Subsequently, critical parameters of the system such as the initial displacement, friction correction factor, the apparent frequency and the spring constant were determined and discussed. The simple experimental set-up and convenient theoretical approach allow us to characterise the marble motion under the influence of a magnet with good accuracy.     

Analysis of parasitic feed-through capacitance effect in closed-loop drive circuit design for capacitive micro-gyroscope

The drive axis of a capacitive micro-gyroscope sensor forms an ‘electrical-mechanical’ resonator with closed-loop drive circuits when the gyro is in full operation. The parasitic feed-through capacitance, which exists between the driving and sensing electrodes of the sensor, induces two main negative effects: preventing the expected ‘electrical-mechanical’ oscillation and introducing an undesired high frequency ‘electrical’ oscillation. In this paper, mathematical expression of the critical parasitic feed-through capacitance allowing the occurrence of ‘electrical-mechanical’ oscillation is derived for the first time. Based on the derived expression, a conclusion that increasing the polarization voltage on the sensor mass be the only electrical way to increase the critical value of parasitic feed-through capacitance is revealed. Then with an implemented silicon chip for the drive circuit, the reason of occurring electrical oscillation is analyzed, and an effective solution to avoid the electrical oscillation referred as increasing the polarization voltage is proposed. Experiments on a capacitive micro-gyroscope prototype show that when the polarization voltage is increased from 10 to 18 V, the closed-loop drive circuit eliminates possibility of the electrical oscillation effectively. As a result, the proposed electrical oscillation solution has been verified.     

并列双导体在交变磁场中的电磁效应探讨

该文针对并列双导体在交变磁场交变作用下的电磁效应进行了探讨。在建立并列双导体交变 磁场中的基本电磁模型和等效分布参数网络模型的基础上,深入分析了并列双导体在交变磁场激励下的电磁效应和电流行为机理。实验结果显示,所提出的电流行为模型很好地解释了并列双导体在发电运行时出现的电流高频振荡现象。     

Resonant Magnetic Field Sensor With Frequency Output

This paper presents a novel type of resonant magnetic field sensor exploiting the Lorentz force and providing a frequency output. The mechanical resonator, a cantilever structure, is embedded as the frequency-determining element in an electrical oscillator. By generating an electrical current proportional to the position of the cantilever, a Lorentz force acting like an additional equivalent spring is exerted on the cantilever in the presence of a magnetic field. Thus, the oscillation frequency of the system, which is a function of the resonator's equivalent spring constant, is modulated by the magnetic field to be measured. The resonant magnetic field sensor is fabricated using an industrial CMOS process, followed by a two-mask micromachining sequence to release the cantilever structure. The characterized devices show a sensitivity of 60 kHz/Tesla at their resonance frequency$f_0= 175~ kHz$and a short-term frequency stability of 0.025 Hz, which corresponds to a resolution below 1$~mu T$. The devices can thus be used for Earth magnetic field applications, such as an electronic compass. The novel resonant magnetic field sensor benefits from an efficient continuous offset cancellation technique, which consist in evaluating the frequency difference measured with and without excitation current as output signal. 1676     

Evolution of long-span bridge response to wind-numerical simulation and discussion

Flutter and buffeting are two important phenomena of long-span bridges susceptible to wind actions. When the wind velocity increases to the bridge flutter velocity, an initial or self-excited multi-frequency vibration in laminar flow becomes single-frequency flutter instability. Similarly, in turbulent flow, the multi-frequency buffeting vibration develops into a single-frequency dominated divergent vibration that can also be interpreted as flutter instability. Even though this transition from buffeting to flutter was observed in wind tunnel tests, the mechanism of transition from multi-frequency type of buffeting to single-frequency type of flutter has not been well demonstrated numerically. Some existent explanations on the occurrence of flutter are very generic and even somewhat confusing. An attempt to reinvestigate numerically the transition of these two phenomena was made in the present study. The established procedure demonstrates numerically how a pre-flutter multi-frequency free vibration and a multi-frequency buffeting vibration merge into a single-frequency dominated flutter at the flutter critical wind velocity. It is concluded that the modal coupling effect forces all modes to vibrate mainly in a frequency close to the oscillation frequency of the critical flutter mode. The oscillation frequency of each mode itself does not merge to that of the critical mode. As a result, some confusing concepts in flutter vibrations are clarified and the mechanisms of the vibration transition process are better understood. Numerical analyses of the Humen suspension bridge with a main span of 888 m were conducted to facilitate the discussions.     

Frequency Domain Analysis of Oscillatory Modes in Decentralized Control Systems

A frequency domain technique for analysis of oscillations in decentralized control systems is proposed. Controllability and observability of an oscillatory mode are evaluated by using computer graphics. Coupling functions are used in the modal analysis of decentralized control. Remote signals are analyzed for possible applications where a critical oscillation mode is controllable in a station but observable in another station.     

硅微振动陀螺仪驱动器自激驱动研究

为了提高硅微机械陀螺仪的检测精度,稳定驱动振动速度的幅度和频率,采用了硅微机械陀螺仪自激驱动方式.该方式能够使驱动振动自动稳定在陀螺仪驱动模态的谐振频率上.同时,采用自动增益控制(AGC)保持恒定的驱动振动幅度.根据自激驱动电路原理和现有的陀螺样品,建立了陀螺仪驱动动力学方程的等效电路模型.设计、制作了自激驱动电路,仿真和实验结果表明该方法切实可行.     

静电刚度式谐振微加速度计闭环驱动控制

分析了谐振微加速度计闭环驱动控制的要求,并根据要求建立了幅度和频率自适应控制的双闭环驱动分析模型．鉴于系统的高阶非线性,采用近似平均法分析了系统的稳态平衡点和稳定条件．对基于锁相技术的频率跟踪环,得到了环路频率稳定跟踪的积分控制器临界条件．对基于自动增益的幅度控制环,分析表明在没有PI控制器时不能实现恒幅振动,在引入PI控制器后,振动幅度与品质因数和频率无关;同时,较小的直流参考电压能实现同样大的振幅．仿真结果有效的验证了上述结论,理论分析和仿真有助于驱动电路的设计和调试．