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On-chip integrated solenoid inductors with nanogranular FeCoTiO magnetic cores have been fabricated. Both single-layered and multilayered magnetic cores with different geometries were studied. An inductance of 14.2 nH was achieved...
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On-chip integrated solenoid inductors with nanogranular FeCoTiO magnetic cores have been fabricated. Both single-layered and multilayered magnetic cores with different geometries were studied. An inductance of 14.2 nH was achieved when using a multilayered core structure and keeping the device area of 0.14 mm2. The inductance of the magnetic core inductor is times that of the air core inductor, and the quality factor is 7.5. The permeability trends calculated from inductance were compared with the permeability spectra of the patterned FeCoTiO films measured by an improved shorted microstrip transmission line perturbation method. Consistent results have been obtained after considering the demagnetization effect of the magnetic core with high permeability.
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On-chip integrated solenoid inductors with multilayered nanogranular magnetic cores have been designed and fabricated on silicon wafers. Both decoupled and coupled inductors with multilayered magnetic cores were studied. For the d...
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On-chip integrated solenoid inductors with multilayered nanogranular magnetic cores have been designed and fabricated on silicon wafers. Both decoupled and coupled inductors with multilayered magnetic cores were studied. For the decoupled inductor, an inductance of 14.2 nH or an equivalent inductance area density greater than 100 nH/mm(2) was obtained, which is about 14 times of that of the air-core inductor, and the quality factor is 7.5 at 130 MHz. For the coupled inductor, an even higher peak quality factor of 17 was achieved at 300 MHz, however, the inductance area density decreased to 34 nH/mm(2). The reason of the enhanced peak quality factor was attributed to less spike domains on the edge of the closure-loop shaped magnetic core, and therefore higher permeability and more uniform uniaxial anisotropy. (C) 2017 Elsevier Ltd. All rights reserved.
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Soft magnetic films with high resistivity at high frequencies are required in areas like magnetic microinductors for communication devices and automotive industry. The hetero-amorphous structure composed of metal ferromagnetic ins...
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Soft magnetic films with high resistivity at high frequencies are required in areas like magnetic microinductors for communication devices and automotive industry. The hetero-amorphous structure composed of metal ferromagnetic insulator films exhibits much higher resistivity in contrast to the conventional nanocrystalline structures because it holds magnetic softness without exchange interaction between the metal particles. Their high saturation magnetization and high resistivity are beneficial to obtain high power density and low loss in thin film inductors that can be used for R.F - Integrated Circuits. This paper reports some results concerning the high frequency behaviour of the electrical and magnetic properties for [FeCoB/(SiO2)](.)n thin films. The annealed [FeCoB/(SiO2)](.)60 thin films with the resistivity p congruent to 48.2 m Omega(.)m, saturation magnetization M-s congruent to 149 emu/g and coercive field H-c congruent to 7 Oe were used for the frequency testings. This system exhibits a good electrical and magnetic response in the high frequency range.
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A comparison of on-chip inductors with magnetic materials from previous studies is presented and examined. Results from on-chip inductors with magnetic material integrated into a 90 nm CMOS processes are presented. The inductors ...
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A comparison of on-chip inductors with magnetic materials from previous studies is presented and examined. Results from on-chip inductors with magnetic material integrated into a 90 nm CMOS processes are presented. The inductors use copper metallization and amorphous Co-Zr-Ta magnetic material. Inductance densities of up to 1700 nH/mm$^{2}$ were obtained thanks to inductance increases of up to 31 times, significantly greater than previously published on-chip inductors. With such improvements, the effects of eddy currents, skin effect, and proximity effect become clearly visible at higher frequencies. Co-Zr-Ta was chosen for its good combination of high permeability, good stability at high temperature ($>250^{circ}$C), high saturation magnetization, low magnetostriction, high resistivity, minimal hysteretic loss, and compatibility with silicon technology. The Co-Zr-Ta alloy can operate at frequencies up to 9.8 GHz, but trade-offs exist between frequency, inductance, and quality factor. Our inductors with thick copper and thicker magnetic films have dc resistances as low as 0.04 $Omega$, and quality factors of up to 8 at frequencies as low as 40 MHz.
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We have designed and fabricated a radio-frequency (RF) planar integrated inductor using Permalloy-SiO{sub}2 granular film as the magnetic core. By controlling the composition and microstructure, we produced a granular film with ex...
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We have designed and fabricated a radio-frequency (RF) planar integrated inductor using Permalloy-SiO{sub}2 granular film as the magnetic core. By controlling the composition and microstructure, we produced a granular film with excellent soft magnetic properties and high electrical resistivity. The inductance L of the inductor with granular Permalloy-SiO{sub}2 magnetic film increased 6 % to 15%, compared to that of an air-core inductor, and the quality factor Q value was high, approaching 10 in the frequency range of 2-3 GHz. The controllable anisotropy of the granular film generated in deposition process gives the magnetic inductor a very high self-resonance frequency peak-over 6 GHz.
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Copper is generally used as a conductor in an air-core spiral thin film inductor. But the inductance of the air-corespiral inductor is very low. In order to improve the inductance,permalloy is used as a conductor in this simulatio...
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Copper is generally used as a conductor in an air-core spiral thin film inductor. But the inductance of the air-corespiral inductor is very low. In order to improve the inductance,permalloy is used as a conductor in this simulation study. Theinductance are 953nH and 184nH at 10MHz with permalloyconductor is larger than that of the inductor with copperconductor about ten times and the quality factors are 1.4 and 2.5at 10 MHz in the permalloy and copper coil inductor, respectively.Consequently, we propose the possibility of inductor using thepermalloy as the conductor in 10MHz range.
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Successful implementation of on-chip power conversion using ferromagnetic inductors requires both high power efficiency and high power density. The theoretical limits to power density and efficiency possible with thin film ferroma...
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Successful implementation of on-chip power conversion using ferromagnetic inductors requires both high power efficiency and high power density. The theoretical limits to power density and efficiency possible with thin film ferromagnetic inductors in a buck converter topology with and without coupling are explored. Power density can be related to energy density of the inductor, while efficiency can be related to Q and the DC resistance loss of the inductor. To achieve 100 ${rm A/cm}^{2}$ for a 100 MHz 2:1 V converter witha 90% inductor efficiency, a peak Q of more than 8 is required with an energy storage of more than 5 ${rm nJ/mm}^{2}$. Using coupling, the power density can be further increased, but is ultimately limited by DC resistance loss in the coils. Figures of merit (FOM) for comparing inductors of various designs are also discussed.
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Using a DC-magnetron sputtering system, we fabricated several forms of double-sided coupling thin-film inductors on a PCB (Printed Circuit Board). Due to the effects of winding forms and thickness of the film, the inductance, Q fa...
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Using a DC-magnetron sputtering system, we fabricated several forms of double-sided coupling thin-film inductors on a PCB (Printed Circuit Board). Due to the effects of winding forms and thickness of the film, the inductance, Q factor and resonance frequency of the inductors are different. Of the three types of inductors covering the same area, the meander inductor has the highest resonance frequency (up to 400 MHz), the circular-spiral inductor has the largest inductance (up to 1 μH/cm~2) and Q factor (up to 25) at low frequency, and the hexagon-spiral inductor has moderate inductance and Q factor at an intermediate frequency. So the proper choice of winding form will depend on the specific application.
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Saturation in thin film coupled magnetic inductors was measured as a function of dc current in both windings. A simple mathematical model was created to approximate the inductor saturation level in the presence of the two currents...
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Saturation in thin film coupled magnetic inductors was measured as a function of dc current in both windings. A simple mathematical model was created to approximate the inductor saturation level in the presence of the two currents. The model was compared both to FEM calculations of saturation in a linear model and to the experimental findings. Using the mathematical model, an expression for the maximum dc current and maximum flux levels in the yokes was derived for a two phase coupled buck converter, as a function of coupling.
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Satellite Test of the Equivalence Principle (STEP) proposes to use niobium thin film strip-line circuits on precision quartz assemblies to achieve on-orbit differential acceleration sensitivities of $10^{-18} {rm g}$. The acceler...
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Satellite Test of the Equivalence Principle (STEP) proposes to use niobium thin film strip-line circuits on precision quartz assemblies to achieve on-orbit differential acceleration sensitivities of $10^{-18} {rm g}$. The acceleration is determined from a displacement measurement under known spring stiffness. Currents trapped in niobium circuits (400nm thick, 100 $mu{rm m}$ wide) provide magnetic spring forces, and in conjunction with a SQUID magnetometer, the displacement measurement. We have studied the effect of substrate surface roughness on the critical current and temperature of niobium thin film strip-line circuits. We have observed a critical current that decreases with increasing surface roughness, with no change in critical temperature. We attribute the decrease in critical current to a flux penetration barrier at the strip-line edge that decreases with increasing surface roughness. This is a significant finding for the development of the STEP instrument, since anomalous flux penetration at the edge of circuits can degrade performance, add SQUID sensor noise, and lead to trapped flux instabilities.
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