Inductors For Use Research Articles

Construction and testing of a common mode choke for cryogenic detector pre-amplifiers

Common-mode choke inductors are useful tools for resolving grounding issues in large detector systems. Using inductive components on cryogenic pre-amplifier boards has so far been prevented by the poor low-temperature performance of common ferrite materialssuch as NiZn and MnZn. Recentlydeveloped nanocrystallineand amorphous ferrite materials promise improved performance up to the point where using magnetics at liquid mitrogen temperatures becomes feasible. This research applies the work of Yin et al. on characterizing ferrite materials by constructing and testing a common mode choke inductor for use on detector pre-amplifiers for the ELT first generation instruments.

Analysis and Optimization of Multi-Winding Toroidal Inductors for Use in Multilayered Technologies

The aim of this paper is to compare the performance of planar toroidal inductors and circular spiral inductors in multilayered technologies, in terms of achievable inductance density. New multi-winding toroidal inductor geometry is proposed to cover as much of the integration area as possible with the component footprint. The optimization of planar multi-winding toroidal inductors in multilayered substrates is investigated theoretically, and closed formulae are derived for their inductances as a function of geometrical parameters for any given value of the number of windings in the coil. The model obtained is validated experimentally and through electromagnetic simulation. Comparing the inductance of multi-winding toroidal inductors and compact spiral inductors allows us to update previously reported selection rules for the most suitable topology that leads to the most compact design.

Integrated Magnetic Nanoinductors

This paper demonstrates the feasibility of the realization of on-chip inductors for use in microwave and millimeter-wave devices using ultraminiaturized on-chip vertical nanohelices. The inductors are constructed by depositing a thin film of closely packed, vertically aligned Nickel nanohelices. The film is fabricated using a CMOS-compatible glancing angle physical vapor deposition method. The resulting nanostructured inductors are characterized from 10 to 70 GHz and are found to have inductances of 6 pH/ $\mu \text{m}^{2}$ , 60 times larger than conventional on-chip planar spiral inductors. A quality factor of three is measured and the results indicate that it continues to improve above 70 GHz, while inductance values remain relatively constant. The proposed nanostructured inductors can significantly reduce the chip area, and consequently the cost, of radio frequency and millimeter-wave integrated circuits. In addition, the nanostructured inductors offer significantly larger operation bandwidth than on-chip planar structures operating at frequencies above 100 GHz.

Design and Implementation of PCB Inductors With Litz-Wire Structure for Conventional-Size Large-Signal Domestic Induction Heating Applications

Printed circuit board (PCB) implementations provide high repeatability and ease of manufacturing as well as potential cost savings for many applications. An optimization procedure is proposed for designing PCB inductors for use in domestic induction cooktops. Cables for classical inductors are built of multistranded round litz wire for efficiency reasons. A planar litz structure in a PCB has been applied to achieve a similar performance to that of traditional constructions (in terms of maximum output power, inductive efficiency, and thermal behavior). The inductor performance has been optimized by a finite-element-analysis-tool-based method taking into account the power losses in rectangular cross-sectional tracks of the cable as well as the geometrical constraints of PCB implementations and the requirements of the associated electronics. Finally, the proposed method has been validated by means of experimental measurements under large-signal conditions on a PCB inductor prototype.

A Practical, Accurate and Very General Core Loss Model for Nonsinusoidal Waveforms

Nonsinusoidal voltage waveforms are quite common in high frequency power conversion magnetics. Low frequency nonsinusoidal waveforms are also common in ac motor applications with waveforms such as pulsewidth modulation and six-step. Previous attempts to model these losses, based on the Steinmetz equation, can work only in a limited range of frequencies, flux density excitations, and waveforms. In this paper, we present a very practical, yet very general and accurate model, for core loss calculations in case of nonsinusoidal voltage waveforms. We show the model is equally applicable to low and high frequencies, metallic as well as nonmetallic (e.g., ferrites) core materials, by comparing the model prediction with measured data for various waveforms, frequencies, and flux densities. The model can be used for the design of high frequency transformers and inductors for use in switched mode power supplies. The model can also be used for ac motors where it is hard to estimate derating factor and to avoid uncontrolled temperature rise

A flexible micromachined planar spiral inductor for use as an artificial tactile mechanoreceptor

Abstract A micromachined planar spiral inductor was created for use as a passive mechanoreceptor element in a tactile sensor. Simulations and experiments were conducted to examine the change in inductance and the deformation in elements implanted in a silicone rubber medium. The results of both showed that the implanted reception inductors had a reception area specific to their direction. The experiments showed that when the inductors were embedded at a depth of 1 mm in a silicone rubber medium with a Young’s modulus of 0.98 MPa, the practical minimal spacing between them was 2 mm, and the practical minimal displacement they could detect was 100 μm. Using a spectrum ranging from 0 to 130 MHz, up to eleven implanted inductors could be measured simultaneously. The fabricated reception inductors had high robustness, high sensitivity, and high repeatability. When several were serially connected using two electrical lines, one single frequency spectrum of the circuit could provide information from all of them.

Thin surface mounting type inductor and its application (high-performance inductor)

In recent years there have been increasing demands for the power supplies of microprocessors to supply a high current at a low voltage while maintaining a favorable load response performance. This in turn requires inductors for use as dc-dc converters to have low winding resistance and low inductance. Consequently, these inductors now incorporate many vertical-structure parts due to low production costs. Assuming further miniaturization of electronic equipment and components, however, vertical parts are likely to be adversely affected by the expanding magnetic field that interlinks with the winding region. We performed magnetic field analysis on a new method of decreasing the interlinking magnetic fluxes in the winding region by improving the core structure and winding technique. It was found that, by providing a number of windings on a laterally structured core and by connecting them cumulatively, the magnetic fields induced in the gap areas could be removed from the winding region. This inductor proved to yield an outstanding low-loss performance when used as a dc-dc converter for high-frequency operation.

The application of saturable turn-on snubbers to IGBT bridge-leg circuits

The turn-on loss of high-speed insulated gate bipolar transistors (IGBTs) accounts for a significant proportion of the total switching energy. In many applications, this loss is increased by the energy associated with diode reverse recovery of current. Such energy is absorbed by the IGBT switch at high voltage. Linear turn-on snubber inductors may be used to control the turn-on loss, diode reverse recovery, and electromagnetic compatibility (EMC). These snubbers have the disadvantage of involving substantial stored energy that must be reset, normally by dissipation. An alternative is to use a saturable turn-on snubber inductor, which stores substantially less energy than a linear inductor. In this paper, the suitability of saturable turn-on snubber inductors for use with IGBTs is investigated, and possible circuit topologies for single-ended and bridge-leg applications are proposed. Mathematical analysis, simulation, and practical results are presented for the saturable inductor turn-on snubber circuit topologies.

Q optimization of RF inductors for use in NMR probes

Radiofrequency inductors are important components of many NMR probe circuits, and a high quality factor Q of these inductors is necessary to achieve good signal-to-noise ratios. We have designed high Q inductors using an optimum coil diameter to coil length ratio of the order of 2.54. The latter was calculated from Lorenz's inductance formula for a solenoid and checked experimentally using a series of inductors of various diameters and lengths. The results show good agreement between theory and practice.

Fabrication of a Composite Inductance Using Co-Metal Amorphous Multilayer Films

Multilayer films consisting of Co 84 Zr 5.5 Nb 10.5 and Co 79 Zr 10 Mo 9 Ni 2 amorphous layers with SiO 2 intermediate layers were prepared. An inductor for use in high frequency applications was fabricated from the film samples and an Ni-Zn ferrite yoke. In order to improve the high frequency characteristics, films fabricated into stripes were studied. Films were annealed in a magnetic field and the frequency response of multilayer films was measured at frequencies from 0.01 MHz to 200 MHz. Films with stripes showed better frequency characteristics than did films without stripes. An inductor fabricated from films with stripes with a total thickness of 20 ?m and ferrite yokes exhibited an inductance of over 10 ?H at 1 MHz, with frequency characteristics improved over those of Ni-Zn alone.

Analysis of Square-Spiral Inductors for Use in MMIC's (Short Paper)

A method analysis of square spiral inductors for use in monolithic microwave integrated circuits (MMIC's) is presented. The method is based on the coupled microstrip-line theory and incorporates a novel solution to the multicoupled-line problem. The analysis includes the effect of the discontinuities at the right-angled bends in the lines, and also the feedback effect where the lead-out bridge crosses the lines. The method can be used to analyze components with an arbitrary number of spiral turns. Theoretical results are compared with the measured S-parameters of a 3 1/2-turn component over the range 2-12 GHz, and reasonable agreement between the two is found.

Wireless Telegraphy 1

(1) IF the last four parts of the sixth volume of the Jahrbuch der drahtlosen Telegraphie und Telephonic, part 3 is almost wholly devoted to an account of the doings of the recent International Radio-telegraph Conference in London, and of the fruits of their labours. In part 4 there is a return to scientific and technical matters, the principal article being one which concludes an elaborate piece of work, both theoretical and experimental, by F. Miiller, on the oscillations in three coupled circuits. Part 5 contains several articles of interest. One, by S. Loewe, on the calibration of thermo-elements for accurate quantitative work—chiefly in connection with the measurement of small high-frequency currents—may be useful to others than those in Hertzian research. A very elaborate technical study of a resonance inductor for use with alternating current of 1000 periods per second is contributed by S. Kimura. An article by G. Seibt describes apparatus for the exhaustive testing of mineral substances with a view to their usefulness as detectors of electrical oscillations. Part 6 contains a paper by P. Jégou on the utility of acoustic resonance in wireless telegraphy—a matter that has received considerable attention of late on account of the widespread use of rapid sparks, producing musical notes, in signalling. F. Kiebitz contributes two articles, one dealing with an elaboration of Bjerknes's method of measuring the decay coefficient of a circuit, the other describing new experiments on antennae consisting of long wires stretched horizontally at a height of a few metres above the surface of the earth. It is found that the state of the ground under the horizontal antennae greatly affects the efficiency with which such antennae can radiate. This article is followed by an interesting correspondence on the same subject.