Resistors For Use Research Articles

Development of a voltage controlled resistor for use in a self-balancing resistance bridge.

We report on a simple design for a voltage controlled resistor that can operate in a continuous range from ∼50 Ω to over ∼100 kΩ. The device consists of a light emitting diode (LED) placed near a photocell. Varying the voltage across the LED changes its brightness, which, in turn, changes the resistance of the photocell. The resistance of the photoresistor is measured by calibrating the output of a nearby phototransistor against the photoresistor resistance, allowing for an independent measurement of the resistance. The performance of the device is tested in the context of a temperature measuring system involving a Wheatstone bridge.

Stable Overload Operation of High-Temperature Superconductor Protective Resistors

The use of high-temperature superconductor (HTS) resistors to protect electrical equipment and ac networks from emergency short-circuit currents and single phase-to-ground faults has been considered. It has been proposed to use a stable overload operation in HTS composite wires to enhance the speed of response and thermal stability of HTS current-limiting devices. Design solutions for the use of stabilized low-resistance HTS wires in protective resistors for ac networks have been developed that increase the resistance inserted in the circuit by several orders of magnitude. The characteristics of first-generation HTS wires with high critical parameters in the resistive state have been measured in a wide current overload range. Prototypes of instantaneous thermally stable current-limiting devices with HTS protective resistors have been fabricated and tested. The design parameters of HTS protective resistors for use in electric power networks have been calculated.

Compact chromium oxide thin film resistors for use in nanoscale quantum circuits

We report on the electrical characterisation of a series of thin amorphous chromium oxide (CrOx) films, grown by dc sputtering, to evaluate their suitability for use as on-chip resistors in nanoelectronics. By increasing the level of oxygen doping, the room-temperature sheet resistance of the CrOx films was varied from 28 Ω/◻ to 32.6 kΩ/◻. The variation in resistance with cooling to 4.2 K in liquid helium was investigated; the sheet resistance at 4.2 K varied with composition from 65 Ω/◻ to above 20 GΩ/◻. All of the films measured displayed linear current–voltage characteristics at all measured temperatures. For on-chip devices for quantum phase-slip measurements using niobium–silicon nanowires, interfaces between niobium–silicon and chromium oxide are required. We also characterised the contact resistance for one CrOx composition at an interface with niobium–silicon. We found that a gold intermediate layer is favourable: the specific contact resistivity of chromium-oxide-to-gold interfaces was 0.14 mΩcm2, much lower than the value for direct CrOx to niobium–silicon contact. We conclude that these chromium oxide films are suitable for use in nanoscale circuits as high-value resistors, with resistivity tunable by oxygen content.

Identification of a force-sensing resistor for tactile applications

A force-sensing resistor is a conductive polymer that exhibits a decrease in resistance as the force applied at its surface increases. The aim of this study is to identify the characteristics of the force-sensing resistor for use in a refreshable and portable E-Braille device that can assist the blind and visually impaired persons. The force-sensing resistor is placed within a component dynamic testing device that is composed of a linear actuator that can generate different displacement loading profiles and a load cell that measures the applied forces. The system records the voltage, force, and the displacement profiles. Several strategies are used in the identification process. First, the mechanical properties of the force-sensing resistor are experimentally characterized. A second-order mechanical system whose parameters are function of the exciting frequency is created based on the results of this experiment. The performance of this model is evaluated using several test inputs. In an attempt to better identify the force-sensing resistor, alternative higher order linear and nonlinear models, including Hammerstein, Wiener, and Hammerstein–Wiener, are proposed using system identification techniques. The accuracy and robustness of these models are assessed using various loading profiles. The outputs of these models are compared with the experimental results.

Fabrication of high-value standard resistors

The National Institute of Standards and Technology (NIST) has fabricated stable, transportable 10 M/spl Omega/ and 1 G/spl Omega/ standard resistors for use in an international comparison of high resistances. This fabrication process is being applied to the construction of standard resistors of values up to 10 T/spl Omega/, with initial results indicating significant improvements in stability and fewer adverse effects induced by mechanical shock and vibration.

Millimeter-wave response in NbN(g)/Al nanobridges

The testing of NbN(g) nanobridges with Al direct shunt resistors for use as millimeter-wave Josephson mixers is discussed. The NbN(g)/Al nanobridges have a nearly sinusoidal current-phase relation, high resistance, well-defined gap structure at approximately 4 mV, large I/sub J/ R/sub N/ products of approximately 3 mV, and nonhysteresis I-V curves. By means of the Al direct shunt, the effective noise temperature T/sub N//sup eff/ of the NbN(g) nanobridges, which was calculated by transition-state theory, was reduced to 4.2 K as a result of reducing the self-heating and noise rounding effects. The NbN(g)/Al nanobridges show almost ideal Josephson response to millimeter-wave radiation at 106 GHz. The well-pronounced Josephson steps were observed up to approximately 4 mV. The observed systematic decreasing of the step heights with increasing the RF current can be accounted for by the effect of the thermal noise if an effective noise temperature of T/sub N/=15 K (at i/sub RF/=3) is assumed. The IF peaks in the Josephson mixing were obtained up to the bias voltage of approximately 1.2 mV. The NEP was about 3*10/sup -20/ W/Hz at 4.2 K.

Application and development of a ceramics resistor for use as a neutral grounding resistor (NGR)

A super-compact SF/sub 6/ gas insulated neutral grounding resistor (NGR) is presented that uses recently developed high-power resistors made of a novel ceramic material. The microstructure, voltage-current characteristics, and current-carrying characteristics of the resistor element are examined. The composition and features of the NGR are discussed. >

Thick film chip resistors for use as low temperature thermometers

We have measured the resistance and magnetoresistance of commercially produced thick film resistors in the range 80 K-15 mK and in fields up to 20 T. These resistors behave similarly to those produced by another manufacturer and characterized recently by a Japanese group. Between 2.5 and 0.1 K the resistance of a 1 kΩ resistor can be fit to R=A exp(B/T 1 4 ) . A 100 kΩ resistor appears to fit a similar expression between 1.6 and 6 K and fits a T −1 2 law from 8 to 80 K. These resistors are very stable upon thermal cycling, have a small magnetoresistance, and should be useful as thermometers over a wide temperature range.

PolySwitch PTC Devices-A New Low-Resistance Conductive Polymer-Based PTC Device for Overcurrent Protection

Positive temperature coefficient (PTC) resistors for use as overcurrent protectors are now available with normal conduction mode resistances of about 0.04 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Omega</tex> . This resistance is significantly lower than devices made from heretofore available barium titanate ceramics. PolySwitchTM overcurrent protectors are made from conductive polymer compositions, which are newly developed materials. Fabrication of a PolySwitch device includes the creation of the base conductive polymer composite, melt forming it to device shape, attachment of leads, and packaging. The final product looks like a disc capacitor but acts like a solid-state circuit breaker or resettable fuse. The source of the PTC effect in these compositions is volume expansion upon heating and the subsequent disruption of connecting carbon black chains. Resistance characteristics of these compositions are reproducible and consistent from device to device; the concepts of a minimum and maximum base resistance and a resistance recovery curve are discussed. Polymer volume compaction processes are responsible for the recovery behavior. The physics of PolySwitch device behavior is explained by Joule heating. The characteristics important to the designer are ultimate trip current as a function of ambient temperature, a property of thermal and electrical equilibrium; and the trip-time characteristic, a property of the nonequilibrium dynamic response. Knowledge of both these charactistics allows the designer to quickly choose a PolySwitch device for his particular job.

Low firing temperature resistors for use on glass : C. Huang and S. J. Stein. Proc. Int. Packaging & Production Conf. Brighton 16–18 October, 1973

Low firing temperature resistors for use on glass : C. Huang and S. J. Stein. Proc. Int. Packaging & Production Conf. Brighton 16–18 October, 1973

Three-terminal shielded resistors for fast electrometers

The design of electrometer feedback resistors for use at frequencies up to the kilohertz range is discussed. It is shown experimentally that the addition of capacitive coupling between the electrometer output and the center of the feedback resistor, combined with suitable shielding, gives substantially better performance at high frequencies than is obtainable with more conventional designs.

Low temperature thermometry in high magnetic fields. III. Carbon resistors (0.5–4.2 K); thermocouples.

The magnetoresistance of 1/2 W, grade 1002, Speer carbon resistors with nominal room temperature resistances of 100, 200, and 470 Ω and of 1/8 W, 10 Ω, Allen-Bradley resistors was measured at various temperatures between 0.5 K and 4.2 K in static magnetic fields up to 140 kG. In this temperature range the maximum magnetic field induced temperature error of these thermometers amounts to 14%. The Allen-Bradley unit is to be preferred over the Speer resistors for use as a thermometer in a magnetic field for the following reasons: it has a more reproducible and regular magnetic field dependence, greater temperature sensitivity, and its much smaller physical size facilitates its incorporation in experimental apparatus where dimensions are restricted. One drawback of the 10 Ω Allen-Bradley resistor is its relatively high impedance at the lowest temperatures. In addition, the effects of magnetic fields up to 150 kG on the characteristics of Chromel P/Au+0.07 at.% Fe and Chromel P/constantan (type E) thermocouples were determined in the temperature range 4.2–45 K. A description is given of the measuring apparatus along with a discussion of possible measurement errors and the necessary precautions which must be observed. The magnetic field induced temperature errors for the Chromel P/Au+0.07 at.% Fe thermocouples are relatively large at temperatures below 20 K, and are nonreproducible between sections of gold-iron wire taken from the same lot. We do not recommend the use of these thermocouples below 20 K at fields greater than 50 kG. In contrast, Chromel P/constantan thermocouples have small, reproducible temperature errors up to 150 kG for 4.2≤T≤45 K. The data indicate that even in strong magnetic fields, at temperatures above 20 K, it is practical to correct for magnetic field induced temperature errors when using thermocouples. The reproducibility of the field induced errors in wires from different sources is still an open question and is worthy of further investigation.

Buried-guarded layer ion-implanted resistors

Megohm silicon monolithic resistors have been fabricated with sheet resistances up to 120 kΩ/□ using an implanted p-layer resistor which is buried under an implanted n-guard layer. The n-guard layer protects against slice-to-slice variations of the fixed surface charge, and was made using phosphorus doses and energy of 1.5-5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 30 keV. Resistors have been fabricated up to 20 MΩ; sheet resistances were in the range of 7-120 kΩ/□ using boron doses and energies of 1-3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">:12</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 30-300 keV. The sheet resistance, voltage dependence of resistance, temperature coefficients, junction leakage, and parasitic capacitance have been measured for different implantation parameters. This process has been used to fabricate two matched 8-MΩ resistors for use in a high input impedance differential preamplifier integrated circuit. A match of 2 percent and a magnitude tolerance of ±10 percent has been achieved. The temperature coefficient of resistance (TCR) is about 4000 ppm/°C and tracks within 400 ppm/ °C. These resistors are linear up to ∼1 V, about 50 times higher bias voltage than required in the application. The structure and fabrication are compatible with present monolithic silicon integrated circuit processing.

High reliability resistors for use in submerged cable repeaters : S. Osborne, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 35

High reliability resistors for use in submerged cable repeaters : S. Osborne, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 35

Modified Speer Resistors for Use as Low Temperature Thermometers

Modified Speer Resistors for Use as Low Temperature Thermometers

The fabrication of cermet resistors using a rejection-mask technique

A copper rejection-mask technique is developed for the fabrication of chromium-silicon monoxide cermet resistors for use in thin-film circuitry. A comparison is made with the direct-etch method, which employs a solution of hydrofluoric and nitric acid.

Recent developments in resistors for use at high voltages

Typical applications for small low-power high-voltage resistors are outlined, and the properties of the solid carbon-resin, solid carbon-rubber and carbon-resin film resistors used in these applications are briefly considered. Various parameters used to indicate non-linearity are compared, and the problem of maintaining accurate voltage division over a range of applied voltages is discussed. The development of improved high-voltage resistors for use in the potential-dividing chain of a large electrostatic generator, where the components had to withstand the effects of occasional very-high-voltage surges, is described.This improved performance was obtained from resistors by utilizing a film of conducting tin oxide protected with a covering of high electric strength and by including an internal spark-gap. These resistors are useful for high-voltage applications generally, and their behaviour on test is briefly described.

Fixed Resistors for Use at High Temperatures

Fixed Resistors for Use at High Temperatures

Glass Resistor for Use in Vacuum Systems

This article describes the construction of a conductive glass resistor intended for operation in a sealed high vacuum system. The resistor is small, having a body size of 0.195 in. long and ⅛ in. diameter, and resistance values from 0.25 to 15 megohms can be achieved. A power dissipation of 25 milliwatts is normal and in vacuum, the operating temperature is approximately 65°C. After suitable initial outgassing, no appreciable amount of gas is evolved into the vacuum system as a result of operating the resistors.

Discussion on “A robust 1 ohm sub-standard resistor for use at high frequencies”

Discussion on “A robust 1 ohm sub-standard resistor for use at high frequencies”