Design and Simulation of PVDF‐MOSFET Based MEMS Hydrophone

Abstract

Modeling has become a vital tool of investigation in all fields, since experimenting with real systems is not only costly, but also time‐consuming and even impossible in some situations. This work presents the design and simulation of an integrated PVDF‐based MEMS hydrophone with improved sensitivity, which contains a MOSFET sense amplifier. The piezoelectric polymer, polyvinylidene fluoride (PVDF), senses the input acoustic signal. As hydrophone size decreases, it becomes necessary to provide an amplifier or buffer in close proximity to avoid sensitivity loss due to interconnect capacitance. This suggests the concept of hydrophones merged with electronics in an integrated circuit environment. So, the integration of PVDF with an on‐chip MOSFET is implemented. The extended gate electrode of the MOSFET is placed over an epitaxial layer isolated from the silicon substrate and is padded with a dielectric layer, SU‐8, which significantly reduces the extended gate capacitance and, therefore, increases the sensor sensitivity. The variation of the transducer output when the input acoustic signal is applied is studied. The simulation is done using the MEMS simulation software, Coventorware.     

电容层析成像系统中径向电极的研究

由于电容层析成像系统中电容测量非常困难,常采用在相邻电极间嵌入径向电极的方法来改善电容敏感场的分布.文中对8电极电容层析成像系统进行了具体的仿真实验和理论分析,并对径向电极及其嵌入尺寸对电容传感器的电容值及敏感场分布的影响进行了研究,根据各项参数对电容传感器性能的影响以及传感器结构参数的优化目标函数,确定了径向电极的最优嵌入尺寸.实验结果表明:采用径向电极最优嵌入尺寸的电容层析成像系统,能够缩小测量电容值的动态变化范围,降低数据采集电路的设计难度,同时还能够提高电容响应的灵敏度,改善电容传感器敏感场的分布,提高电容层析成像系统的性能.     

基于CAV424的电容式压力传感器测量电路设计

随着差动式硅电容传感器广泛应用于各行各业中,对差动电容信号的检测至关重要.文中提出基于CAV424电容检测芯片作为前置检测单元,实现了电容压力传感器测量电路.该电路具有稳定性好,抗干扰性强,且通过非线性补偿有良好的线性.实验结果表明,实际电路与理论分析具有良好的一致性.     

基于CAV424的电容式液位检测系统

介绍一种基于CAV424的电容式液位检测系统。根据电容式液位传感器的工作原理,传感器两个极板间的电容值会随液位的改变而改变,系统利用电容/电压转换芯片CAV424将电容值转化为电压值输出,然后使用16位高精度∑-△模数转换器AD7705再将电压值转换为数字信号,交由单片机对数据做进一步的处理,如数码管显示及电流输出。电流输出部分由12位串行数模转换器AD7943和4~20mA的电压/电流转换器组成。系统具有RS-485远传接口。     

电容式压力传感器的厚膜集成化研究

采用厚膜传感技术研制电容式感压元件,并通过厚膜混合集成技术将信号处理电路集成在感压元件上成为一体,进行电容式压力传感器的厚膜集成化研究。结果表明：研制成的新型厚膜电容式集成压力传感器,线性达到0．5％,迟滞小于0．5％,具有重复性好,受分布电容,寄生电容影响小,精度高,抗过载,耐腐蚀等特点,对厚膜感压元件,信号处理电路的设计与平面化加工以及集成化等进行了介绍,并对集成化中相关工艺,兼容性及性能进行了讨论。     

Capacitance Transducers with a Thermistor Bridge in the Measurement Circuit that Are Based on Self-Excited Oscillators

The main relationships describing a steady-state operating mode of self-excited-generator transducers with a self-balanced thermistor bridge, in which the transduced capacitance is connected in parallel with the thermistor, are presented. The results of tests of the transducer at frequencies of 2 and 3 MHz show that its sensitivity (200 kHz/pF) may be several hundreds of times higher than the sensitivity of self-excited-generator transducers in which the transduced capacitance is included into the frequency-setting measuring LC circuit.     

顺序控制技术在X(S)M系列密炼机中的应用

密炼机是橡胶加工设备,其卸料装置、锁紧装置均由液压回路来实现其工作要求。对于卸料装置和锁紧装置,其动作次序为:卸料门锁松、卸料门开、卸料门关、卸料门锁紧。这四个动作分别由四个液压缸执行。为了让四个液压缸按设定的先后次序动作,液压回路方案中需设计顺序控制回路。通过对行程控制和压力控制两大类四种实现顺序动作的回路进行比较,重点说明压力继电器在X(S)M系列密炼机中的应用。介绍X(S)M系列密炼机液压传动系统的技术参数,总结密炼机顺序动作回路故障并提出维护方法,对密炼机的正确使用具有指导意义。     

扩散硅压力传感器特性分析及其应用举例

扩散硅压力传感器具有良好的性能和稳定性。本文说明了扩散硅压力传感器的工作原理,详细分析了对其进行温度综合补偿的电路,然后结合实例,介绍了压力传感器的接口电路和对其进行非线性校正的方法。     

DIUS-1.15M Mobile Hardware–Software Structuroscopy System

It is shown that by measuring the magnetic field in a specially shaped hole made in the magnetic circuit of a measuring transducer and the tangential component of the magnetic field in the transducer’s interpolar space near the surface of an object being magnetized, it is possible to locally determine the relative values of the magnetic properties of the test-object substance. The physical rationale is provided for a technique that makes it possible to determine the entirety of hysteresis characteristics and significantly expand the ranges of measurement of magnetic properties. The difference is established between the structural sensitivities of magnetic properties locally determined in terms of “flux–internal field” (the properties of matter) and “flux in the product–current in the windings” (the properties of “body”) coordinates. It is shown that it is possible and expedient to simultaneously measure and jointly analyze the magnetic characteristics of matter and “body”. Information is provided on the DIUS-1.15M mobile hardware–software system, intended for implementing single- and multiparameter techniques of monitoring the structure–phase and stress–strain states of ferromagnetic materials and objects based on the proposed measurement procedures.     

新型运载火箭中电容式液位传感器接口专用集成电路

为了提高新型航天运载火箭中电容式液位传感器系统的电容检测性能,设计了一款适用于航天运载火箭中电容式液位传感器的接口专用集成电路(Application Specitic Integrated Circuit,ASIC)芯片。首先,完成了整体电路的系统级设计,实现了对电容式液位传感器输出电容的线性检测,将传感器输出电容量转化为与之呈线性关系的电压量输出。然后,对接口ASIC芯片的线性度、噪声特性和温度环境适应性进行了理论分析与研究。最后,采用0.5μm CMOS工艺完成接口ASIC的流片,并进行了芯片的性能测试。实际测试结果显示,芯片电容检测非线性为0.005%,输出噪声密度3.7aF/Hz~(1/2)(待测电容40pF),电容测量稳定性7.4×10-5 pF(参考电容40pF,待测电容40pF,1σ,1h),输出零位温度系数4.5μV/℃。测试结果证明,该接口ASIC的电容检测性能已经达到国外最高性能的电容式液位传感器液位测量芯片的水准,可以广泛应用到多种电容式检测传感器中。     

厚膜电容式集成压力传感器压元件研究

采用厚膜技术研制新型电容式集成压力传感器用感压元件。具有抗干扰能力,灵敏度高,受分布电容、寄生电容影响小、耐腐蚀,耐高温的特点。文中主要介绍其电容式感压元件的原理、设计,并对非线性等相关技术及工艺问题进行了探讨。     

采用锁相技术的微小电容检测电路

】描述了一种应用于电容式传感器的微小电容检测电路,此电路采用锁相技术的原理,成本较低,具有较好的线性度和较高的灵敏度。     

Model Based Tuning of Controller for Non‐Linear Hemispherical Tank Processes

Abstract

A non linear liquid level process represented by a 5 liter hemispherical tank was subjected to dynamic analysis using a step response technique. The data fitted a first order plus dead time model with an error of less than 3 percent. The level was measured using an on‐line Honeywell capacitance sensor. From the model parameters, PI and fuzzy tuned PI controllers were designed using MATLAB. The closed loop performance was studied for both the servo and regulator problems. Based on the overshoot, rise time, settling time, and ISE, it is found that the Fuzzy tuned PI controller is better suited for this process.     

基于MEMS传感器的无线传感网络节点的硬件设计

为了解决对建筑物的结构健康安全监测进行在线监测的问题,采用微机电系统(MEMS)技术和无线传感器网络技术相结合的方法,提出了一种基于磁驱动增大检测电流的新型电容式加速度传感器结构,介绍了其工作原理,并设计了该传感器的电容检测电路,在ANSYS仿真软件上对传感器性能进行了评价,在Multisim上对检测电路进行了模拟仿真;仿真结果表明,该传感器可以检测三维加速度信号,静态灵敏度可达0.558μm/g,动态测量范围为10 g,电路实际输出与仿真结果相符,符合要求;在节点整体方案设计中以低功耗的MSP430F1611作为控制MCU,以CC2430芯片实现无线收发,配合周围接口电路实现了位移信号的监测功能;采用片内温度传感器对节点进行了测试。测试结果表明,该节点能够完成监测,满足设计要求。     

A novel capacitive system for the concentration measurement of pneumatically conveyed pulverized fuel at power stations

A novel capacitive system for the concentration measurement of gas–solid flow in pneumatically conveyed pulverized fuel at power stations has been developed. The capacitance sensor for measuring the concentration uses source-grid sensing electrodes. An active sensor and a dummy sensor are used to form a differential configuration. In order to eliminate baseline drift, to be immune to stray capacitance, and to ensure accurate measurement under very low solids/air mass flux ratio conditions, a correlated double sample (CDS) technique and lock-in detector with closed loop are used in the interface circuit. A laboratory scale pneumatically conveyed pulverized fuel loop system incorporating facilities for calibration has been fabricated for this purpose. The test section is a vertical ceramic tube of diameter 100 mm with an upward flow direction and pulverized fuel has been used as the solid phase. Results demonstrate that the system is capable of achieving linearity within ±5% at different temperatures or moisture content.     

Extension of the Acceptable Active-Loss Range of a Transducer in a Capacitance-to-Frequency Conversion

The main factors affecting the accuracy of the conversion of transducer capacitance into a frequency in a self-excited oscillator with a thermistor bridge are considered. It is shown that introducing a correction into the feedback circuit extends the range of acceptable active-conductance values by approximately two orders of magnitude with an unaltered accuracy of transducer capacitance measurements based on determining the frequency of self-excited oscillations.     

基于加权SVD截断共轭梯度的ECT图像重建算法

针对电容层析成像技术中的“软场”效应和病态问题,基于灵敏度矩阵的奇异值分解理论,提出了一种加权SVD截断共轭梯度的ECT图像重建算法,给出了算法的数学模型,完成了算法的收敛性分析和证明,并将其应用在电容层析成像系统的图像重建中。仿真和实验结果表明,同LBP算法和CG算法相比,该算法有成像效果好,成像速度快,易于实现等特点。     

高线性非接触式电容位移传感器

设计一种新型电容式微位移传感器,给出了检测电路.原理为20 kHz的正弦信号加在传感器上,传感器产生的交流电压与电容电极之间的距离成正比.电路包括正弦信号发生电路、精密全波整流电路、滤波电路和信号放大电路.实验证明：该传感器线性度小于3%,分辨率优于0.01 μm.     

摩擦焊模块化测控系统实现

设计基于P89C51RD2单片机的摩擦焊机压力及转速两个测控电路模块,实现对惯性摩擦焊过程关键参数压力及转速的闭环控制.摩擦焊机液压系统控制阀采用可控性较好的电液比例溢流阀,由压力传感器对实际压力进行检测,检测信号进入压力测控电路模块,经A/D转换、运算处理及D/A转换后输入电液比例溢流阀,以实现对摩擦焊接过程压力的连续调节.焊机主轴电动机驱动器采用调速性能较好的变频器,主轴转速由光电旋转编码器进行检测,其脉冲信号直接进入转速测控电路模块,经运算处理及D/A转换后输入变频器,实现调速控制,使焊机主轴电动机可按照焊接工艺的要求得到稳定、准确的转速.实际生产应用表明,压力及转速控制系统工作稳定、操作方便、运行效果良好.     

激光主动探测电路系统设计与实验研究

雪崩光电二极管(APD)因其具有很高的内部增益,被广泛应用于光电探测中.根据雪崩光电二极管的雪崩效应及工作原理,采用APD作为激光回波接收单元来探测“猫眼”目标,设计了接收放大电路,并进行了实验研究.结果表明:此探测电路可探测到“猫眼”目标回波且回波信号包含时间与目标距离信息,可保证后续目标的定位,为激光主动探测系统的...