Resistance Standards Research Articles

A PXI-Based Calibration System for Low-Value AC Resistors

This paper presents a sampling measurement system designed to compare ac standard resistors within a range from 1 $\text{m}\Omega $ to 10 $\Omega $ at frequencies ranging from 40 Hz to 10 kHz and for measurement currents up to 10 A. The system allows simultaneous measurement of both components of impedance of the calibrated resistor relative to the reference resistor. Built on the basis of commercial PXI modules, complemented by modules developed by the authors, the system stands out relatively simple structure and fully automatic operation. In order to reduce the impact of parasitic impedances on the comparison accuracy, a completely automated interchange method and the original way of connecting a digitizer to the compared impedances were applied. The consistency of the measured ac resistance ratios from 1:1 to 1:10 is better than 1 $\mu \Omega /\Omega $ and phase difference better than 6 $\mu $ rad, over the entire frequency range. The results of several comparisons and the analysis of their uncertainty show that for the comparisons of resistors with a resistance ratio close to one, the relative uncertainty of the resistance ratio measurement is 2.3 $\mu \Omega /\Omega $ ( $k=2$ ) over the entire frequency range. The uncertainty of the difference between the time constants of the compared resistors is at the level of 0.2 ns ( $k=2$ ) at 1 kHz.

Applied signal effect in the potentiometric method on the resistance measurements accuracy

In this paper, the effect of applying dc voltage and dc current sources in using the potentiometric method on the accuracy and the uncertainty of the resistance measurements is studied. This study is done practically for the low and high values of standard resistance ranges from 100 to 10 MΩ. The traceability chain for the used resistors is introduced by using the standard resistors 1 Ω Thomas type, 10 kΩ model SR104, and four Hamon transfer standards. The system operation is remotely controlled by using a LabVIEW program to improve the performance. The measurement results and the uncertainty estimation values are discussed to identify the effect of the applied voltage and current on the different resistance ranges measurement.

A study of quantum Hall devices with different working magnetic fields for primary resistance metrology

Two kinds of quantum Hall devices with different working magnetic fields are fabricated and compared with the LEP (Laboratoires d’Electronique Philips) device, which is currently used in the primary resistance standard system of the National Institute of Metrology (NIM) of China. The comparison is made by calibrating the same 1 Ω standard resistor made by the National Measurement Laboratory of Australia using a Tinsley 100 Ω resistor as the intermediate standard and a cryogenic current comparator. The calibrated values from the NIM device with high working magnetic field and those from the LEP device agreed to within −0.69 × 10−9 with an uncertainty of 4.9 × 10−9. The values from the NIM device with low working magnetic field and those from BIPM-2 agreed to within 2.5 × 10−9 with an uncertainty of 7.1 × 10−9.

Development of $1~\Omega $ and $10~\Omega $ Metal-Foil Standard Resistors

Compact superstable standard resistors ranging from $1~\Omega $ to 10 $\text{k}\Omega $ have been under development, and the 4-year evaluation of $1~\Omega $ and $10~\Omega $ resistors is presented in this paper. The typical drift rates of these resistors are around 0.05 $\mu \Omega $ /( $\Omega ~\mathrm {year}$ ). The temperature coefficients have also been evaluated. The performance of these resistors meets the calibration laboratory conditions for the maintenance of resistance standards. This type of resistor is also stable during transportation and can be used for international comparisons.

Development of 1 $\text{M} {\Omega }$ Quantum Hall Array Resistance Standards

We fabricated and evaluated a 1 $\text{M}{\Omega }$ quantum Hall array device with GaAs/AlGaAs substrates. This 1 $\text{M}{\Omega }$ quantized Hall resistance array device consists of 88 Hall bars, and its nominal resistance value is $10^{6} (1-0.034 \times 10^{-6}) ~\Omega $ . The ratio for this nominal value, 10150/131, was derived using the continued fraction expansion method, which adopts the triple-connection technique to minimize the influence of contact resistance and wiring resistance on the quantized resistance value. The fabricated 1 $\text{M}{\Omega }$ quantum Hall array device showed clear and flat ${i=2}$ and 4 plateaus and negligibly small longitudinal resistance. We observed the desired yield ratio of the contact resistance to 2-dimensional electron gas with sufficiently low wiring resistance and sufficiently high insulation resistance and collapse current. These results strongly support the reliability of our 1 $\text{M}{\Omega }$ quantum Hall array device. We have confirmed the desirable performance of the existing calibration system of the 1 $\text{M}{\Omega }$ wire-wound standard resistors based on the array device. We expect that this device will allow us to improve the high-resistance standard system and to convert the small current from electron pumps into easily measurable voltage without decreasing precision.

Determining the Temperature Coefficient of Reference Resistors

The influence of temperature on electrical resistance of standard resistors is presented within this paper. Electrical resistance is like any other quantity temperature dependent. This dependence is specified with the temperature coefficient, which gives the relative change of resistance with temperature. The level of resistance change is not linear as it changes with temperature, and therefore the coefficient is temperature dependent as well. At a certain temperature, its value is equal to zero—the stationary point. Use of the standard resistor at this exact temperature or in a narrow interval around it greatly reduces the influence of temperature on electrical resistance, even if the thermal conditions are not optimal. Measurements of temperature coefficient were taken on a group of standard resistors of the same type in a wide temperature range, and the temperature of the stationary point was determined. Measurements were taken by placing the resistors in an oil bath and changing its set point temperature from 18 \({^{\circ }}\hbox {C}\) to 38 \({^{\circ }}\hbox {C}\). Electrical resistance of each resistor was measured using a resistance bridge, which had its reference resistor placed in a separate thermal enclosure at a constant temperature.

Characterisation of a Selection of AC and DC Resistance Bridges for Standard Platinum Resistance Thermometry

Accurate resistance bridges are used to measure the ratio between the resistance of standard platinum resistance thermometers and a reference (standard) resistor at the level of microkelvin in temperature terms and as such play a critical role in the realisation and dissemination of the ITS-90. For AC bridges, the ratio test unit has been available for some time, and for both AC and DC bridges, the increasing availability of resistance bridge calibrators based on combinatorial calibration has increased the ease with which the accuracy and linearity of resistance bridges may be determined, under conditions which provide a realistic representation of the actual measurement set-up. In this study, the performance of 14 resistance bridges, which were available for testing at NPL, consisting of a range of manufacturers and types, has been evaluated and expressed in terms of the standard deviation of the bridge errors over a given range of ratios, namely s. In general, the bridges are found to comply with the manufacturers’ specifications. The uncertainty of s has also been determined using Monte Carlo techniques and is found to be of the order of 10 % of s for most bridge types.

An FPGA-Based Instrument for En-Masse RRAM Characterization With ns Pulsing Resolution

An FPGA-based instrument with capabilities of on-board oscilloscope and nanoscale pulsing (70 ns @ $\pm$ 10 V) is presented, thus allowing exploration of the nano-scale switching of RRAM devices. The system possesses less than 1% read-out error for resistance range between 1 $\text{k}\Omega$ to 1 $\text{M}\Omega$ , and demonstrated its functionality on characterizing solid-state prototype RRAM devices on wafer; devices exhibiting gradual switching behavior under pulsing with duration spanning between 30 ns to 100 $\mu$ s. The data conversion error-induced degradation on read-out accuracy is studied extensively and verified by standard linear resistor measurements. The integrated oscilloscope capability extends the versatility of our instrument, rendering a powerful tool for processing development of emerging memory technologies but also for testing theoretical hypotheses arising in the new field of memristors.

Composite resistor standard for calibration of measuring transducers in laboratory conditions

Calibration of measuring transducers for precision measurement is done by measuring voltage drop at the resistor standard, produced by output dc current proportional to the input measured value. Resistance fluctuations due to the temperature coefficient of the resistor standard are minor, thanks to the stable temperature conditions in laboratory environment. This fact brings the need to calculate the effect of resistor self-heating on its resistance. This thermal effect, produced by the flow of current through the resistor, is often disregarded. For the precise measurements this can be a significant source of error and must be quantified. This paper describes mathematical model of measurement error, resistor self-heating coefficient is defined, as it?s not usually given in product datasheets. The effect on measurement results is given in detail. Composite resistor standard prototype is described, made from off-the-shelf mass produced components, calculated and hand selected to cancel the self-heating coefficient effects. The prototype is compared to the existing commercially available high performance resistor standard.

マンガン窒化物焼結体の標準抵抗材料への応用

CuMn-related alloys as typified by Manganin, and NiCr-related alloys such as Evanohm are widely used for the materials of standard and precision resistors. These materials have a broad resistance peak around room temperature in the resistance-temperature curve and resistance is stable and insensitive to temperature change and fluctuation around the peak. Therefore these alloys are recognized as superior materials for standard and precision resistors. The antiperovskite manganese nitride compounds, Mn3Ag1-xCuxN, also show a broad resistance-temperature curve around room temperature and the temperature coefficient is comparable to those of Manganin alloys. We found out that this curvature and the peak temperature can be controlled by co-doping with Cu and In or Fe and we demonstrated that the Mn3.03Ag0.62Cu0.19In0.15N shows a low temperature second-order coefficient of resistor, 0.2 (μΩ/Ω)/K2. We have also revealed that the drift rate of the resistance can be decreased by shaping a sintered sample to the 4-terminal fashion.

A 1 k standardresistor device based on quantum Hall array

Quantum metrological standards based on the fundamental physical constants are the trend of modern metrology because of their attributes such as high accuracy, high stability, and good reproducibility. The quantum Hall effect (QHE), which refers to the electronic charge e and the Planck constant h, is used to define the quantum resistance standard. The quantum Hall resistance (RH) of h/2e2 at the filling factori=2 is used as the standard. It is obvious that the RH is non-integral. However the resistors that need to be calibrated each have a decimal value, such as 1 k, 10 k, 100 k, etc. The calibration chain from the non-integral RH to the real resistor is long. The quantum Hall array resistance standards (QHARSs) are invented to solve this problem. The QHARS which are based on the decimal resistance values can shorten the calibration chain, improve the resistance transfer accuracy, and finally realize the quantization of the whole resistance calibration chain. The QHARS can also replace the traditional physical transfer standard resistor and realize the quantization of the transfer standard resistor. The decimal QHARS devices can be realized by connecting single QHE devices in series or parallel with the multiple link technology. In this paper we report the design, fabrication and characterization of a 1 k QHARS device based on the GaAs/AlxGa1-xAs heterostructures. In our design, the 1 k array device consists of only 29 Hall bars. The nominal value of the device is 999.9999658 with a relative deviation of -3.4210-8 from 1 k. The ratio between the maximum and minimum current flowing through the Hall bars is as small as 14.5. The 1 k QHARS devices are measured in the national resistance standard system at a temperature of 1.5 K. The measurement is taken at the central magnetic field of the 2nd quantum Hall plateau. We compare our 1 k QHARS resistor with a 1 k transfer standard resistor using the direct current comparator. The 1 k transfer standard resistor has already been calibrated in advance with our single QHR standard by cryogenic current comparator. Therefore the resistance of our 1 k QHARS resistor can be obtained. The relative deviation between the measured resistance value and the designed value is -1.9610-7with a standard uncertainty of 2.0710-7. The results show that we have realized the 1 k quantum Hall resistance standard device which can be used for the resistance calibration.

Monitoring Dietary Behavior with a Smart Dining Tray

In this article, the authors investigate a new source of information for dietary monitoring: pressure distribution on the surface underneath dining plates. Pressure sensing has been used to consider the weight of the eaten food. The core idea behind their work is that dynamic pressure information can also be used to distinguish between various cutlery-related activities, such as cutting, poking, stirring, or scooping. The authors show how to spot such individual actions in continuous datastreams, assign them to specific containers (main plate, salad bowl), count them (how many bites taken), and relate them to different abstract food categories. They consider two sensing modalities: (1) textile pressure-sensor matrix technology facilitating a smart that looks and feels like a standard tablecloth but provides detailed information on the spatial and temporal pressure; and (2) standard force sensitive resistor (FSR) sensors placed underneath a rigid tray. They also present the results of a new, comprehensive study with 10 subjects, each of whom consumed a total of eight meals chosen from 17 possible main dishes with six possible side dishes; results show an average accuracy of up to 94 percent. This article is part of a special issue on pervasive food.

Simple Two-Transistor Single-Supply Resistor–Capacitor Chaotic Oscillator

We have modified an otherwise standard one-transistor self-biasing resistor–capacitor phase shift oscillator to induce chaotic oscillations. The circuit uses only two transistors, no inductors, and is powered by a single supply voltage. As such, it is an attractive and low-cost source of chaotic oscillations for many applications. We compare experimental results to SPICE simulations, showing good agreement. We qualitatively explain the chaotic dynamics to stem from hysteretic jumps between unstable equilibria, around which growing oscillations exist.

Behavior of 1 Ω resistors at frequencies below 1 Hz and the problem of assigning a dc value

This paper presents a systematic study of the effects of reversals of current polarity on 1 Ω standard resistors. A selection of 1 Ω standards were measured on a dc cryogenic current comparator bridge and also on an ac current comparator bridge operating at 1 Hz. We find that the apparent 4 terminal resistance depends strongly on the dc reversal rate, in one case showing a variation of more than 0.1 μΩ/Ω for cycle times between 10 s and 1000 s. Even in the best cases, effects of at least 0.01 μΩ/Ω are present. Furthermore, the assumption that the apparent resistance value converges to a limiting value for long waiting times after reversal is not always upheld, making it difficult to quote a simple dc value. Existing models of Peltier heating at wire junctions do not completely explain our observations. The problems presented have been the limiting factor for 1 Ω measurements as part of a recent on-site comparison of quantum Hall effect resistance standards.

A Dual-Channel Calibration System for AC Currents and Small AC Voltages

A new current-comparator-based dual-channel calibration system for AC currents and AC voltages in the millivolt range has been developed. The range of generated currents is 1 mA–5 A, and the range of generated voltages is 1–500 mV. The calibration system in-phase and quadrature expanded measurement uncertainties ( $k=2$ ) are within $25\cdot 10^{\mathrm {\mathbf {-6}}}$ . Although the system has been developed primarily for operation at power frequencies, it is also capable of operating at frequencies up to 1000 Hz with slightly increased uncertainties. The traceability to SI units is established through the calibration of AC voltage by means of AC/DC transfer and DC voltage reference, standard resistor, capacitor, and current comparator ratios.

Transportation Effect and Basic Characteristics of Metal-Foil Resistors Examined in an International Trilateral Pilot Study

The transportation effect and other important characteristics of 100 Ω standard resistors of a new construction have been studied. For the transportation effect, four resistors have been transported by air between three national metrology institutes (NMIs): 1) the Korea Research Institute of Standards and Science; 2) the National Institute of Standards and Technology in the USA; and 3) the National Metrology Institute of Japan. Two of the resistors have been transported in hand-carried luggage and the other two by normal air freight. Resistance values as well as other characteristics have been carefully evaluated before and after the transportation to the NMIs. The measurements were done by means of their primary national standards based on the quantum Hall effect. No noticeable difference between the two transportation methods has been detected within a standard uncertainty of 0.01 μQ/Q. Other characteristics, the drift rate: about 0.05 (μQ/Q)/year or less, temperature coefficient: about 0.02 (μQ/Q)/°C or less, and power coefficient: negligible, have also been reported. It is demonstrated that this excellent performance is suitable for utilization in NMIs and international comparisons.

1550nm 레이저 다이오드를 이용한 바나듐 이산화물 박막 기반 2단자 평면형 소자에서의 양방향 전류 트리거링

While most switching devices are based on PN junctions, a single layer can realize a switching device in the case of vanadium dioxide() thin films. In this paper, bidirectional current triggering(switching) is demonstrated in a two-terminal planar device based on a thin film by illuminating the film with an infrared laser at 1550nm. To begin with, a two-terminal planar device, which had a -wide conducting layer and an electrode separation of , was fabricated. A specific bias voltage range for stable bidirectional laser triggering was experimentally obtained by measuring the current-voltage characteristics of the fabricated device in a current-controlled mode. Then, by constructing a test circuit composed of the device, a standard resistor, and a DC voltage source, connected in series, the transient response of laser-triggered current and its response time were investigated with a DC bias voltage, included in the above specific bias voltage range, applied to the device. In the test circuit with a DC voltage source of 3.35V and a resistor, bidirectional laser triggering could be realized with a maximum on-state current of 15mA and a switching contrast of ~78.95.

Ultrastable low-noise current amplifier: A novel device for measuring small electric currents with high accuracy

An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is highly stable versus time, temperature, and current amplitude within the full dynamic range of ±5 nA. The low noise level of 2.4 fA/√Hz helps to keep averaging times short at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Within one week after calibration, the uncertainty contribution from short-term fluctuations and drift of the transresistance is about 0.1 parts per million (ppm). The long-term drift is typically 5 ppm/yr. A high-accuracy variant is available that shows improved stability of the input gain at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electric currents or the calibration of high-ohmic resistors.

<italic> In Situ</italic> Interconnect Failure Prediction Using Canaries

A physics-of-failure-based canary approach for early identification of solder interconnect failures has been developed. The canary is composed of a resistance path formed by a near-zero ohm ceramic chip resistor soldered to pads designed to produce failure earlier than standard pad resistors, which are the target structures. The time to failure of the canary can be adjusted by adjusting the printed wiring board pad dimensions and, hence, the solder interconnect area. The developed canary approach is demonstrated through temperature cycling of the resistors. The pad width of a standard resistor is reduced by 80%, thereby reducing the interconnect life. The results from the temperature cycling experiment prove that the developed canary approach provides advanced warning of failures of the standard pad resistors. The FEA results suggest that there is a 78% increase in the strain range in the canary resistor, as compared with the standard resistor. The Engelmaier model, a physics-of-failure-based model for solder interconnect life estimation under thermal cycling, is modified to take the solder interconnect area into account. The model provides time to failure estimates for the canary and target structures. A comparison of the results from the Engelmaier model and temperature cycling experiment shows that the model provides a good estimate of time to failure of standard resistors and a conservative estimate of time to failure of the canary resistors.

Stop that interference! [Basic Metrology

The esoteric world of setting up and propagating the base SI units with measurements made by relatively simple apparatus to incredible parts-in-a-billion accuracy seems remote and irrelevant to ordinary everyday measurement and control, but the measurements rely on strict adherence to simple basic principles which are relevant right down the measurement chain. For example, many years ago one of us had to set up, maintain and disseminate the SI impedance units, the Farad, Henry and Ohm. This involved learning about the, then new, technique of coaxial measuring circuits as applied to the 1 to 10 kHz frequency range, and their simplicity and beauty was impressive. In these coaxial circuits the terminals of standard capacitors, inductors and resistors are no longer single-conductor binding-posts. They are now coaxial cable sockets and each socket constitutes associated pair of terminals. The inner pin of a socket replaces a binding-post and the screen of the sockets and the interconnecting coaxial cables is continuous with complete conducting screens in which standards are now enclosed. Measures are taken to ensure that whatever current flows through a standard and the inner conductor of each cable, an equal and opposite current flows back through the outer shields. The network of shields should be extended between the primary and secondary windings of instrument supply transformers. Unfortunately this is seldom, if ever, correctly done in commercial instruments and the isolation afforded by the shielding is compromised.