新品展示

莱姆电子推出CTSR系列电流传感器最近,莱姆电子推出了集安全和高性能于一体的CTSR系列电流传感器,适用于包括太阳能系统在内的各种安全关键场合。新系列中的两款传感器可对额定值低至300和600mARMS且频率高达9.5kHz的交流或直流漏电流进行测量。在许多工业或发电场合的故障状态下,CTSR系列传感器设计测量的残余电流或漏电流值会     

莱姆电子推出CTSR系列电流传感器

最近。莱姆电子推出了集安全和高性能于一体的CTSR系列电流传感器,适用于包括太阳能系统在内的各种安全关键场合。新系列中的两款传感器可对额定值低至300和600mARMS且频率高达9．5kHz的交流或直流漏电流进行测量。在许多工业或发电场合的故障状态下,CTSR系列传感器设计测量的残余电流或漏电流值会升高     

闭环霍尔电流传感器在车用电源系统中的应用

介绍闭环霍尔电流传感器的工作原理及其在地面车用电源系统中的应用，实现了对车用电源系统输出电流的隔离测量和控制，解决了地面车辆中大功率发电系统的限流保护问题．     

数字闭环光纤电流传感器暂态特性仿真研究

数字闭环光纤电流传感器暂态特性主要包含频率响应与阶跃响应,对于电力系统的继电保护控制、故障录波等应用领域至关重要。在工程应用中,传统的测试方法由于其测试系统复杂、测试电流信号小等问题,不利于评估光纤电流传感器的暂态特性。利用数字闭环光纤电流传感器的闭环控制机理,提出一种在数字闭环光纤电流传感器反馈回路中添加相位调制激励的方法。首先,分析数字闭环光纤电流传感器的相位调制原理,通过建立数学模型验证相位调制激励的等效性;其次,根据数字闭环光纤电流传感器闭环控制算法,提出频率响应与阶跃响应的调制激励产生方法;最后,利用现有数字闭环光纤电流传感器产品平台完成频率响应与阶跃响应的仿真与测试。结果表明:采用相位调制激励的仿真数据与试验数据最大误差为0.12%,该调制激励方法不需要搭建复杂的测试系统,在现有硬件平台中即可实现不同电流信号的仿真测试。     

基于NB-IoT的分布式光伏电站漏电监测系统

针对分布式光伏电站缺少漏电流无线监测设备的实际情况,介绍一种基于NB-IoT(窄带物联网)无线高精度磁调制电流传感器的漏电监测系统。该系统由感知层、传输层、平台层和应用层四部分构成。通过对影响磁调制传感器精度的定性和定量研究,提出双磁芯半波激励方案,优化传感器设计,提高其精度。汇流箱中的电流传感器采集数据信息通过单片机经由NB-IoT网络传输至云平台。该系统能够实现使用云平台对分布式光伏电站系统漏电流进行在线实时监测和故障定位,且能有效解决分布式光伏电站的漏电监测问题。     

PIC单片机在漏电流保护器中的应用

本文叙述由电流互感器、PIC单片机、运算放大器等组成的智能漏电流保护器及其硬软件设计。智能漏电流保护器具有大漏电流和小漏电流控制,实现报警与保护作用,并具有缺相保护功能。     

雪崩光电二极管体内漏电流的测量分析

体内漏电流是雪崩光电二极管应用的一个重要参数,而一般测量暗电流的方法无法把表面漏电流和体内漏电流分开.本文提出一种测量雪崩光电二极管体内漏电流的方法,推导有关公式,并对宽耗尽层雪崩光电二极管的体内漏电流进行测量分析.     

LEM闭环传感器在信号采样中的应用

LEM传感器可广泛用于电力电子行业的电量控制和测量,以保证系统的高效、可靠性和安全.介绍了LEM闭环电流、电压传感器的性能、基本工作原理以及应用注意事项,给出了该传感器在直流电压、交流电流及电源电压同步信号采样中的应用电路,同时给出了采样电路中采样电阻的选择方法.     

一种考虑漏电流最低损耗的控制器电子模块设计与实现

漏电流损耗占电路能耗的大部分,属于实时变化的动态过程,传统控制器采用堆栈方法,通过对输入信号的控制实现对漏电流损耗的控制,无法适应漏电流的动态变化,不能实现最低损耗控制。为此,设计一种考虑漏电流最低损耗的控制器电子模块,通过模拟电路与CPLD相结合的方法对漏电流最低损耗控制器电子模块进行设计,给出设计的总体结构。通过霍尔传感器对漏电流进行检测,利用比较器将检测的实际漏电流与参考漏电流进行比较,用CPLD形成对应的斩波驱动信号,发送至电压控制器,通过电压控制器对主开关器件的导通和断开进行控制,实现漏电流最低损耗的控制。软件设计中,设计一个调试软件,给出电流最低损耗控制程序和交替斩波程序。实验结果表明,所设计控制器电子模块的漏电流损耗很低,且运行效率高。     

CCD图像传感器电极间漏电流自动化测试系统设计

CCD图像传感器电极间漏电流是反映CCD器件可靠性的一个关键参数,在CCD图像传感器的生产过程中,对其电极间漏电流测试是一个重要的检测筛选环节。基于一种漏电流自动化测试方法,设计了一种CCD电极间漏电流自动化测试系统。该系统可根据不同种类CCD器件,自定义被测信号名称、测试通道地址和测试判据,通过计算机软件控制自动循环扫描,自动采集漏电电流数据,形成标准测试报表。该系统具有设置灵活、操作方便、自动化测试等优点,可有效提升CCD生产检查筛选过程中的测试效率和测试设备的通用性。     

Comparison of Computed RF Current Flow on a Power Line With Full Scale Measurements

Reradiation of an MF/AM broadcast transmitter's signal by a power transmission line can cause serious pattern distortion. A computer model of a power line, developed and tested against scale model measurements over highly conductive ground, has been used to assess the pattern distortion to be expected from a power line proposed for construction, to identify those towers on an existing power line which carry strong RF currents, and to design "detuningn devices to suppress such currents. The accuracy of the computer model's "predictions" is tested in this paper against full-scale measured RF current flow on the skywires of a real power line. A toroidal current probe is described which is suitable in the MF band for current measurement on a large steel lattice structure such as a power line tower. Instrumentation is described for the measurement of either current magnitude only, or of both magnitude and phase. Thus the current flowing on a power line tower is readily measured by this method. Measurements of skywire current are compared with computations using a highly conductive "perfect" ground model, and using the Sommerfeld-Norton ground model for "lossy" ground of conductivity 10 millisiemens/metre and relative permittivity 15. The two ground models result in similar current distributions, with the peaks and minima in the standing wave pattern at the same positions on the skywire. The lossy ground model results in somewhat less current flow due to the damping introduced into the resonant behaviour of the power line.     

Ultralow Current Measurements With Silicon-on-Sapphire Integrator Circuits

This letter reports the results on measurements and modeling of the ultralow current measurement capability of a silicon-on-sapphire current integrator circuit. We have tested the lowest possible current measurable with the device and the noise performance with picoampere input currents. The device is capable of resolving subpicoampere currents with an rms noise of 350 fA in a 110-Hz bandwidth. The device is also capable of digitally measuring currents up to 100 $muhbox{A}$ by employing a pulse-based A/D converters.      

Gain-Enhanced InGaAs–InP Heterojunction Phototransistor With Zn-Doped Mesa Sidewall

A gain-enhanced InGaAs–InP heterojunction phototransistor (GE-HPT) with a Zn-doped mesa sidewall designed to reduce both base-emitter recombination currents and base-collector dark currents is realized. The developed GE-HPT has an optical conversion efficiency as large as 24 kA/W at an incident optical power of 29 nW and a wavelength of 1.55 $mu$m, which is the highest gain yet reported in HPTs. The measured dark current in the base-collector junction is comparable to that of planar-type PIN photodiodes. The high gain and low dark current characteristics of the phototransistors make them promising for use in a weak light detection system.      

Symmetric-gain, zero-offset, self-aligned, and refractory-contact double HBT's

We report double-heterostructure bipolar transistors using refractory emitter and base contacts (WSix/InAs for n-type, and W with rapid diffusion of Zn for p-type) and self-aligned implantation. These devices have near-symmetric gain (∼ 100) across a fairly large current range (∼ four decades), negligible offset voltage, and a weak current gain dependence on device size. This results from suppression of surface recombination obtained using a P-GaAlAs electron barrier at the extrinsic-base surface. We also demonstrate use of a technique for deconvolving various recombination mechanisms. The major gain-limiting mechanisms in these devices are shown to be (a) residual damage from ion implantation and its effects on base transport factor, and (b) Shockley-Read-Hall recombination in the depletion regions and its effect on injection efficiency. Devices similar to the above showed gains approaching theoretical values of ∼ 1000 at high currents, and greater than 10 at picoampere currents when the processing was designed to obtain high lifetime in the implanted region.     

Measurements of leakage currents and the capacitance of the storagecapacitor in a single DRAM cell

Methods of measuring leakage currents and the capacitance of the storage capacitor in a single DRAM cell have been developed for correlation with the electrode shape of the capacitor. In the circuit used for these measurements, the plate electrode of the storage capacitor is connected to the gate of the MOSFET which amplifies the voltage variations of the storage capacitor during the measurements. Here, only a conventional transistor parameter analyzer and a capacitance meter are required for the measurements. For the capacitance measurement, the linear region characteristics of the MOSFET are used to simplify the analysis. For the leakage current measurement, however, the subthreshold region characteristics of the MOSFET are used to enhance the accuracy of the measurement. The results show that the very low leakage currents (down to below 0.1 fA) and the capacitance (37.5 fF) of the storage capacitor can be measured accurately. Further, the leakage current-voltage characteristics of the storage capacitor are discussed by comparing with those of a large area planar capacitor whose structure is the same as the storage capacitor     

Diakoptic theory for multielement antennas

A theory is presented for the analysis of multielement antennas which consist of interconnected, conductive structure elements of electrically small dimensions. The theory is based on the retarded electromagnetic potentials which permit a diakoptic approach to the problem. The antenna is broken up into its individual structure elements. Each element is assumed to be excited by currents which are impressed at its terminals, i.e., junctions with adjacent elements (current coupling) and by the electric fields of the currents and charges on all the other elements (fieid coupling). Both excitations are treated independently. Each impressed current produces a "dominant" current distribution, a characteristic of the element, which can be readily computed. Current coupling is formulated by "intrinsic" impedance matrices which relate the scaler potentials at the terminals of an element, caused by its dominant current distributions, to the impressed currents of the element. Field coupling produces "scatter" currents on all the elements and is formulated by a "fieid-coupling" matrix which relates the scalar potentials at the terminals, caused by field coupling, to the impressed currents at all the terminals. Intrinsic and "field-coupling" matrices are combined to form the "complete" impedance matrix of the diakopted antenna. Enforcing continuity of the currents and equality of the scalar potentials at all the interconnections between the elements yields a system of linear equations for the junction currents and the input impedance of the antenna. Current coupling dominates field coupling. Fieid coupling is primarily affected by the dominant current distributions of the elements, and in general the scatter currents have negligible effect on it. Although detailed numerical investigations will be presented in another paper, a simple example is included here to demonstrate that the diakoptic theory yields very good results even if greatly simplified assumptions are made.     

The Stochastic I-Pot: A Circuit Block for Programming Bias Currents

In this brief, we present the "stochastic I-Pot." It is a circuit element that allows for digitally programming a precise bias current ranging over many decades, from pico-amperes up to hundreds of micro-amperes. I-Pot blocks can be chained within a chip to allow for any arbitrary number of programmable bias currents. The approach only requires to provide the chip with three external pins, the use of an external current measuring instrument, and a computer. This way, once all internal I-Pots have been characterized, they can be programmed through a computer to provide any desired current bias value with very low error. The circuit block turns out to be very practical for experimenting with new circuits (specially when a large number of biases are required), testing wide ranges of biases, introducing means for current mismatch calibration, offsets compensations, etc. using a reduced number of chip pins. We show experimental results of generating bias currents with errors of 0.38% (8 bits) for currents varying from 176 muA to 19.6 pA. Temperature effects are characterized.     

Sampling the mesoscale ocean surface currents with various satellite altimeter configurations

Ten-day composites of maximum cross-correlation (MCC) ocean surface current vectors from 1-km spatial resolution Advanced Very High Resolution Radiometer (AVHRR) 11-/spl mu/m thermal infrared images are used to simulate the ocean surface current retrieval capabilities of three satellite altimeter configurations over a large California coastal region. Ground track positions of the nadir sampling TOPEX/Poseidon (TP; now the Jason-1) satellite altimeters are used to compute the cross-track velocity components from the corresponding optimally interpolated MCC vectors for a ten-day period. Next, the Jason-1-only and the TP plus Jason-1 "tandem mission" sampling are simulated as well as the combination of all available satellite altimeters including European Remote Sensing Satellite 2 and Geosat Follow-On. Finally, we simulate surface current retrievals from the proposed Wide Swath Ocean Altimeter (WSOA), which will have both along- and cross-track velocity components over a spatial swath. Comparisons of vector current fields, their differences, and wavenumber spectra from optimally interpolated maps of the "simulated altimetry velocities" with the corresponding MCC field indicates that (1) the combined coverage from Jason-1 plus TP as well as the combination of all available satellite altimeters results in a better representation of the currents than that of Jason-1 alone and (2) the retrieved currents from the WSOA provide an even greater improvement over the tandem mapping and multiple satellites. It will be possible in the future to regularly map the mesoscale surface currents of the ocean with wide-swath ocean altimeters.     

Efficient method of moments formulation for large PEC scatteringproblems using asymptotic phasefront extraction (APE)

A method is introduced for reducing the exorbitant dependence on computer storage and solution time in the method of moments (MoM) for electrically large electromagnetic (EM) scattering problems. The unknown surface currents on large, smooth parts of a perfect electrical conductor (PEC) scatterer are expressed by an efficient set of linearly phased surface current basis functions. The phasefront characteristics of the surface currents are numerically extracted from known current samples obtained from a lower-frequency solution of the same configuration. The use of such basis functions for efficiently representing the surface currents that are constructed in terms of linearly phased currents at higher frequencies is justified by considering the form of the surface currents predicted by high-frequency asymptotic ray methods. The procedure for extracting the current phasefronts is purely numerical, obviating computationally expensive and nonrobust operations such as ray-tracing, and thus, is amenable to general purpose scattering codes. The new MoM with linearly phased basis functions is shown to greatly relieve the storage and solution time of the conventional MoM while accurately reproducing the induced surface currents and scattered fields of some chosen targets     

Hot-carrier-induced off-state current leakage in submicrometerPMOSFET devices

Hot-carrier-induced off-state leakage (HCIOL) currents were successfully used as a new monitor in characterizing device reliability. HCIOL current increases drastically with reducing channel length, but the stress bias only affects the onset time of HCIOL current. For buried-channel PMOSFET's, only the HCIOL currents at the reverse measurement configuration were dominant. However, in surface-channel devices, HCIOL currents at both forward and reverse configurations became important. An empirical HCIOL current model was developed to quantify device lifetime as a function of channel length and stress voltage. Estimated lifetime results indicated that HCIOL current will impose a major limit on device reliability especially for deep-submicrometer technology and low power applications