共查询到19条相似文献,搜索用时 187 毫秒
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针对纳米光栅微陀螺输出微安甚至皮安级的微弱电流信号,设计微弱电流信号的前置放大电路,研究微弱电流信号检测与电路稳定性的理论,提出一种低成本、低噪声、高信噪比的微弱电流检测方法,即高阻型的I-V转化法,并给出高阻型I-V转化电路的响应带宽计算公式以及电路稳定性的分析方法。通过搭建测试台,对电路性能及功能进行实际测试。实验结果表明:该电路可对皮安级的微弱电流信号进行检测放大,电路灵敏度为10 mV/pA,最大检测误差为1.5%(当输入微弱电流值10 pA时),满足纳米光栅微陀螺的微弱电流检测的需求。 相似文献
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设计了一款基于超导量子干涉仪(SQUID)的直流电阻电桥指零仪电路,该电路可用作高精度电阻电桥中低值电阻(0.1~100Ω)测量的指零仪电路。通过自制SQUID外围电路并优化电路其输入耦合线圈的互感值,实现微弱电桥不平衡电流的精密测量。与传统电阻电桥基于测量不平衡电压的纳伏计指零仪相比,其检测灵敏度在中低值电阻测量范围有数量级的提升。设计的作为指零仪的SQUID磁通锁定环1/f转折频率在2Hz左右,磁通白噪声水平在3.5μΦ0/左右,并且输入线圈与SQUID互感系数高达10nH,其等效的电流白噪声密度0.7pA/。将其用作电阻电桥指零仪测量100Ω标准电阻(工作电流为10mA)的分辨率可达到10-11量级。 相似文献
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《真空科学与技术学报》2019,(4)
针对热阴极电离真空计电参数校准装置中电流源设计的关键技术,本文提出一种用于真空计电参数校准的内置单运放电流源及其非理想化低频等效模型,并通过PSPICE仿真对电路性能进行分析。装置适用于100 MΩ~100 GΩ负载条件,负载为1 GΩ时输出电流相对变化率为0.3×10~(-6)。解决了当前热阴极电离真空计电参数校准装置电流源不适用于低位离子流采样的超高电离真空计的问题,达到校准不同型号热阴极电离真空计离子流放大器的效果,为电参数校准装置的研制提供理论依据及参考。 相似文献
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用XF_1型精密电表校验台对电流表和功率表的检定中,直流电流的供给常用YJ 10A型晶体管稳流器,该稳流器要求在有电流输出的条件下,电流输出端钮不能开路。否则把负载接人电路时,会产生过电压和过电流的现象。为此我们自制了一种直流稳压源附加保护器。 相似文献
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为解决辐射测量传感器输出电流难以准确采集的问题,该文设计并实现一种pA级电流放大器。首先对放大器的低频截止点、高频截止点、噪声特性和漂移等关键指标进行分析,基于电容积分原理设计一种用于pA级电流采集的电荷放大器,并从施加等电位屏蔽、提高绝缘性能、应用相位补偿和抑制噪声四个方面对放大器的性能进行优化,以确保其输出稳定可靠。最后,在多功能校准源Fluke 5720A、标准分压器和标准电阻箱辅助下,将该放大器的输出结果与Keithley 6514的测量结果进行比较,确定该放大器的测量准确度优于1%。并对该放大器的改进方向进行阐述。该放大器已被用于局部放电量在10 pC及其以下的校正脉冲发生器校准中,并取得良好的效果。 相似文献
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相比于传统的串联连接方式,提出了一种基于二进制电抗分流器实现热电转换器共地比较测量的方法,通过串联连接的方式实现交流电流量程扩展。二进制电抗分流器产生两路共地可自校的电流输出,为热电转换器之间进行相互比较提供已知关系的1:1电流比例;该方法可以减少电流泄漏和三通连接器串联连接的影响。基于这种共地测量方法,热电变换器结合100 mA和1 A分流器进行了实验分析,测量频率范围1~200 kHz,同时在串联模式下进行换臂测量。实验结果表明基于二进制电抗分流器和换臂法可以很好地消除泄露电流所引起的测量误差,且两种不同方法在200 kHz频率下一致性优于3 μA/A。3种不同热电变换器和分流器组合在10 mA~1 A测量电流下交流转换误差一致性优于6 μA/A。 相似文献
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The quantization of flux in a closed superconducting circuit is used to provide a stable reference current. A 10-mA current source is coupled through a toroidal transformer to a DC superconducting quantum interference device (SQUID) input, and the resulting signal is fed back as an error current. The result is a net flux linkage that exhibits short-term stability of 1 part in 109/h. The net current is quantized with a step size of 59.4 nA, and it will exhibit the same stability as the flux provided the mutual inductance of the transformer remains constant. This current is passed through a precise 100-Ω resistor and compared against Zener diode references. The observed temperature coefficient for the flux transformer is 28.5±3 ppm/K at 4.2 K. Possible sources for the temperature dependence are discussed 相似文献
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针对传统信号源输出电压较低,负载能力弱且无法闭环稳压、稳频的缺点,研制了一种输出电压有效值为40V,负载电流为1A的高稳定度纯净正弦波功率信号源,以适应陀螺测试等系统的需求.本文对该功率信号源系统结构和电路原理进行了详细的分析.样机实验结果表明:该信号源具有功率大、稳定度高,准确度高和低谐波含量的优点,具有良好的应用前景. 相似文献
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A highly sensitive CMOS chopper amplifier for an oxygen probe is described. It is integrated in a 2-μm double-poly p-well CMOS process. The chip uses only a single 5-V voltage source, and no external components are needed. It is realized by using the current mode chopper technique to overcome the low frequency noise and drift problems. The clock feedthrough generated by the chopper circuit is reduced by using the switched-capacitor-filter technique. The switched-capacitor technique is also used to implement the function of demodulation. The simulated current is converted into an output voltage with a slope of approximately 100 mV/nA. The current signal from 0.2 to 8 nA can be measured with a nonlinearity of 3.5%. Experimental results are given showing the performance of this amplifier 相似文献
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介绍了用于提高电压标准源负载能力的外接功率放大电路的设计原理及组成,该电路通过对称式的设计方法和认真筛选器件,使其具有附加误差小、跟踪准确度高等优点,解决了一般电压标准源源电流输出能力不足的问题. 相似文献
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《IEEE transactions on instrumentation and measurement》1973,22(4):391-394
The design of a stable sine-wave source for error determination of ac-measuring instruments is discussed. The electronic amplitude control circuit has been constructed using standard integrated circuits. The fluctuations of its rms output voltage, observed over the period of 1 h, are 1 · 10-6 peak-to-peak. Since the total harmonic distortion is less than 1 · 10-3, its contribution to the error of the rms value may be neglected. 相似文献
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A time-based CMOS integrated potentiostatic control circuit has been designed and fabricated. The design maintains a constant bias potential between the reference and working electrodes for an amperometric chemical sensor. A technique of converting input currents into time for amperometric measurements is proposed. This technique eliminates current amplifying circuitry, reduces matching problems, and increases dynamic range while saving on area and power consumption. Redox currents ranging from 1 pA to 200 nA can be measured with a maximum nonlinearity of /spl plusmn/0.1% over this range. The design can be used to generate cyclic voltammograms for an electrochemical reaction by sweeping the voltages across a range specified by the user. Analog inputs are processed and digital outputs are generated without requiring a power-hungry A/D converter. A prototype chip has been fabricated in the 0.5-/spl mu/m AMI CMOS process. Experimental results are reported showing the performance of the circuit as a chemical sensor. 相似文献
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van den Brom H.E. de la Court P. Rietveld G. 《IEEE transactions on instrumentation and measurement》2005,54(2):554-558
A high accuracy current source has been developed for the generation of very small currents (below 200 pA) based on applying a linear voltage ramp to a capacitor. Using software-controlled compensation for the nonlinearity of the voltage ramp, a stable current can be reached within a few seconds. A voltage ramp within typically 10/spl middot/10/sup -6/ of any desired value between less than 1 mV/s and several hundreds of mV/s can be realized. Using a high quality air-dielectric capacitor, currents below 200 pA can be generated with an uncertainty of 20 /spl mu/A/A (k = 2), with a lower limit of 2.0 aA (k = 2). 相似文献
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Chung W.-S. Kim K.-H. Cha H.-W. 《IEEE transactions on instrumentation and measurement》1992,41(3):441-443
A linear operational transconductance amplifier (OTA) is described that consists of a linear transconductor and a translinear current gain cell followed by three current mirrors. The proposed circuit has superior linearity and temperature characteristic when compared with the commercially available OTA. A prototype circuit with a transconductance of 50 μS has been built with discrete bipolar transistors producing a linearity error of less than ±20% over an input voltage range from -0.8 to 0.8 V. The prototype OTA circuit also exhibits a transconductance that is linearly dependent on a bias current varying over four decades with a sensitivity of 1 S/A 相似文献