共查询到20条相似文献,搜索用时 137 毫秒
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YJZV-1型直流标准电流电压源在检定精密直流电工仪表过程中作为一种电源被使用,其组成部分主要包括:基准源、保护电路、稳压电源及输出显示等。但在该设备使用过程中也往往会出现一些问题或故障,给检定工作带来麻烦。笔者通过多年工作经验现就该设备经常出现的一些故障和调修方法总结如下,以供参考。 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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研制了8mm波段(26.5~40.0GHz)精密功率测量系统,它既可用作校准终端型功率计的小功率传递标准,又可用于稳定8mm波段信号源的输出功率,为各种精密测量提供稳定的低输出反射系数信号源。 测量系统由高方向性3dB定向耦合器及其旁臂精密功率计和稳幅环路组成。3dB耦合器采用宽壁Tchebycheff耦合孔阵设计,方向性达40dB;精密功率计由恒温热敏电阻座和高精确度四端电阻自平衡电桥组成;稳幅环路包括一台多用稳幅器和PIN电调衰减器。恒温热敏电阻座的温度漂移小于±1μW/℃·h;直流替代功率测量准确度为±(0.1%+0.2μW);稳幅后,信号源输出功率稳定度优于±0.02%/30min,此时毋需调配,测量系统等效信号源的输出VSWR小于1.05(反射系数模值小于0.025)。 文中给出了该测量系统的测量数据和用作小功率传递标准时的误差分析。 相似文献
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设计一种基于斜波式发生器原理可编程数字控制精密延时电路,用恒流源电路充放电和18位的DA转换器分别接入高速比较器的两端,DA转换器预先设定一电压基准,恒流源充电电容达到电压基准,高速比较器开始反转,形成一个触发脉冲信号,然后充电电容通过高速二极管快速放电重新计时。设计成18bit数字控制可编程动态范围2ps的采集时间间隔,提高采集信号的精度和频率。 相似文献
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Callegaro L. D'Elia V. Trinchera B. 《IEEE transactions on instrumentation and measurement》2007,56(4):1198-1201
A current source, which is to be employed in the calibration of low-current meters (picoammeters and electrometers), is presented here. The output current range is 100 fA to 100 pA and is directly traceable to calibrated standards of dc voltage, capacitance, and time period. The source is based on a low- frequency (ap1 mHz) trapezoidal signal generator, which charges and discharges a gas-dielectric capacitor; the voltage is monitored with a voltmeter that is triggered by a precision time base. The source has been employed during March 2006 for the Italian participation to the supplementary comparison EUROMET.EM-S24 and will be part of an extension of the Italian national standard of dc current. However, being composed of low-cost electronics and common commercial instrumentation, the source can also find useful application in secondary calibration laboratories. 相似文献
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A micromachined electrometer, based on the concept of a variable capacitor, has been designed, modeled, fabricated, and tested. The device presented in this paper functions as a modulated variable capacitor, wherein a dc charge to be measured is up-modulated and converted to an ac voltage output, thus improving the signal-to-noise ratio. The device was fabricated in a commercial standard SOI micromachining process without the need for any additional processing steps. The electrometer was tested in both air and vacuum at room temperature. In air, it has a charge-to-voltage conversion gain of 2.06 nV/e, and a measured charge noise floor of 52.4 e/rtHz. To reduce the effects of input leakage current, an electrically isolated capacitor has been introduced between the variable capacitor and input to sensor electronics. Methods to improve the sensitivity and resolution are suggested while the long-term stability of these sensors is modeled and discussed. 相似文献
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Measuring the Electron’s Charge and the Fine-Structure Constant by Counting Electrons on a Capacitor
E. R. Williams Ruby N. Ghosh John M. Martinis 《Journal of research of the National Institute of Standards and Technology》1992,97(2):299-304
The charge of the electron can be determined by simply placing a known number of electrons on one electrode of a capacitor and measuring the voltage, Vs, across the capacitor. If Vs is measured in terms of the Josephson volt and the capacitor is measured in SI units then the fine-structure constant is the quantity determined. Recent developments involving single electron tunneling, SET, have shown bow to count the electrons as well as how to make an electrometer with sufficient sensitivity to measure the charge. 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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为了实现对微弱测量仪器进行测试与校准,根据恒流源电路的思想,研制了一种由运算放大器构成的微弱电流源。在微弱电流产生中,利用恒压源和高精度标准电阻,通过V-I变换来实现微弱电流的输出;设计反馈调节网络,来解决普通电流源实现微弱电流输出易受负载影响的缺点,消除负载对输出电流的影响,同时,实现100pA~1μA量程的微弱电流输出。为提高电流源的性能,电路中采取了屏蔽和滤波处理,来解决噪声的影响。经过测试,结果表明该电路的电流范围在100pA~1 μA之间,电流源稳定可靠。在1nA时,误差不超过0.08nA。 相似文献