External Inductor Research Articles

Numerical and experimental investigation on contactless resonant sensors

This paper reports numerical and experimental investigation on a (bulk and etch silicon on insulator) BESOI MEMS device. The implemented contactless actuation principle, exploits Lorentz forces exerted on a conductive-non magnetic surface of the sensor. These forces derive from the interaction between the eddy-currents and the radial magnetic field, both generated by a sinusoidally driven external inductor. Both excitation and readout strategies are performed remotely via a magnetic strategy. The sensor proposed here has been first analytically and numerically studied by using CoventorWare™ 2008, then the device prototype has been fabricated and a preliminary experimental campaign has been performed to characterize the system in terms of variation of its resonance frequency against changes in the sensor mass.

Macrosegregation Behavior of Ti-10V-2Fe-3Al Alloy During Vacuum Consumable Arc Remelting Process

The effects of melting current and magnetic field in vacuum consumable arc remelting (VAR) process on the macrosegregation of Ti-10V-2Fe-3Al ingot are investigated in this paper. The results show that Fe content increases gradually from the bottom to the top of ingots along axial direction and the degree of macrosegregation is greater in the radial direction in the middle of the ingot versus the top and bottom. The macrosegregation rate of Fe element is higher with melting current of 2.6 kA than that of 1.7 kA in Ti-10V-2Al-3Fe ingot. There are two forces, buoyancy and Lorentz forces which arise from the flow of current through the pool of VAR when without magnetic stirring, but a new Lorentz force arising from the presence of external inductors occurs with adding magnetic stirring which decreases the macrosegregation rate of Fe element in Ti-10V-2Fe-3Al.

A High-Efficiency, Auto Mode-Hop, Variable-Voltage, Ripple Control Buck Converter

In this paper, a simple yet efficient auto mode-hop ripple control structure for buck converters with light load operation enhancement is proposed. The converter, which operates under a wide range of input and output voltages, makes use of a state-dependent hysteretic comparator. Depending on the output current, the converter automatically changes the operating mode. This improves the efficiency and reduces the output voltage ripple for a wide range of output currents for given input and output voltages. The sensitivity of the output voltage to the circuit elements is less than 14%, which is seven times lower than that for conventional converters. To assess the efficiency of the proposed converter, it is designed and implemented with commercially available components. The converter provides an output voltage in the range of 0.9V to 31V for load currents of up to 3A when the input voltage is in the range of 5V to 32V. Analytical design expressions which model the operation of the converter are also presented. This circuit can be implemented easily in a single chip with an external inductor and capacitor for both fixed and variable output voltage applications.

Energy-Recovery Sustain Driver With Low Circulating Current

An energy-recovery sustain driver with low circulating current for a plasma display panel (PDP) is proposed. The energy stored in the external resonant inductors during the reverse-recovery periods of the diodes in the sustain driver is transferred to the input voltage source and the energy-recovery capacitors. The proposed sustain driver can reduce the circulating current and relieve the thermal problems of the main sustain switches. Experimental results obtained on a 42-in high-definition PDP with a resolution of 1024 × 768 are discussed.

Zero-voltage switching phase shift full-bridge step-up converter with integrated magnetic structure

A zero-voltage switching (ZVS) phase shift full-bridge (PSFB) step-up converter with integrated magnetic structure is proposed. In order to improve ZVS ranges, an external inductor is imposed. Especially, to save the volume of the magnetic core of external inductor, the external inductor and transformer are integrated into one magnetic core and then the coupling is formed. Furthermore, coupling coefficients are analysed and can be adjusted by the gaps in the three legs of magnetic core. Besides, the fluxes and the maximum flux density in the three legs of magnetic core are also analysed. Finally, a 100 W prototype converter is made and the experimental results are given to verify the analysis.

A Universal Equivalent Circuit Model for Ceramic Capacitors

A physics-based equivalent circuit model of the ceramic capacitor is proposed, which can reproduce frequency characteristics of its impedance including the often observed yet hitherto physically unexplained kinks appearing above the primary series resonance frequency. The model can also account for parasitic effects of external inductances. In order to efficiently analyze and gain engineering insight into ceramic capacitors with a large number of metallic laminae, a two-dimensional method of moments is developed that treats the laminar structure as a uniform, effective medium. It turns out that the primary resonance and the kinks can be well understood and modeled by a lossy transmission line stub with a drastic wavelength reduction. The capacitor model is completed by adding components describing the skin effect and external inductances. The modeled impedance stays within a 4% margin of error up to 5 GHz. The proposed model could greatly improve the accuracy of power distribution network simulation.

Predicting Fusing Current for Encapsulated Wire Bonds under Transient Loads

For high power IC chips, as device size inevitably decreases, the wire diameter unfortunately must decrease due to the need of finer pitch wires. Fusing or melting of wirebonds thus increasingly becomes one of the potential failure issues for such IC's. Experiments were performed under transient loads on dummy packages having aluminum, gold, or copper wires of different dimensions. A finite element model was constructed that correlates very well with the observed maximum operating currents for such wirebonds under actual experimental test conditions. A qualitative observation of typical current profiles, as fusing conditions were approached, was that current would reach a maximum value very early in the pulse, and then fall gradually. One goal achieved through the modeling was to show that the current in the wire falls with time due to the heating of the wire material. Correspondingly, the wire reaches the melting temperature not at the peak current but rather at the end of pulse. Further, modeling shows that knowledge of external resistance and inductance of the experimental set up are highly significant in determining the details of a fusing event, but if known along with the temperature-dependent wire properties, the simulation can predict the correct voltage and current response of the part with 2% error. On the other hand, lack of external circuit characteristics may lead to completely incorrect results. For instance, the assumption that current is constant until the wire heats to fusing temperature, or that current and temperature both rise monotonically to maximum values until the wire fuses, are almost certain to be wrong. The work has been carried out for single pulse events as well as pulse trains.

An Octave-Range, Watt-Level, Fully-Integrated CMOS Switching Power Mixer Array for Linearization and Back-Off-Efficiency Improvement

Non-constant envelope modulation schemes have become commonplace in cellular applications due to their higher spectral efficiency. Linear PAs driven by an RF transmitter are usually used to generate these signals faithfully at the expense of power efficiency. Separate processing of amplitude and phase information (e.g., EER or polar modulation) has been proposed [1] as a way of improving the system power efficiency. However, many of these schemes require an efficient high-power low-frequency supply modulator to reconstruct the amplitude information. This can be done, for instance, using a switching DC-to-DC converter with its own limitations in efficiency, bandwidth, and area that also requires an external inductor [2]. Even for an ideal supply modulator, the amplitude dynamic range of the PA itself is limited by the gate-to-drain feedthrough and its associated AM-to-AM and AM-to-PM conversion. (For example, in [3] a 10dB change in the supply results in a 5° phase shift at the output.) Although a digitally-modulated polar PA [4] has been shown as a possible solution at lower power levels, its implementation in a wideband watt-level fully-integrated CMOS PA for non-constant modulation has not yet been demonstrated.

Numerical and Experimental Investigation on Contactless Resonant Sensors

This paper reports numerical and experimental investigation on a BESOI-MEMS device. The implemented contactless actuation principle exploits Lorentz forces exerted on a conductive-non magnetic surface of the sensor, deriving from interaction between the eddy currents and the radial magnetic field, both generated by a sinusoidally driven external inductor. Both excitation and readout strategies are performed remotely via a magnetic strategy; moreover, the conceived sensor has been first numerically studied by using CoventorWare™2008, then the device prototype has been fabricated and a preliminary experimental campaign has been performed to characterize the system in terms of variation of its resonance frequency.

SOME PECULIARITIES OF USING OF DIELECTRIC RESONATORS IN MICROWAVE SURFACE IMPEDANCE MEASUREMENTS

A simple equivalent circuit of the dielectric resonator technique, using for measurement of the surface resistance of the samples of non-standard dimensions, was considered and analyzed. It was shown that the coefficient (the geometry factor) relating the surface resistance of the sample to the quality factor may be different in the cases when the inductive resistance (caused by the external inductance) of the sample exceeds significantly its active resistance and when these resistances are of the same order. It was shown too, that an anomaly in the RS versus T dependence (i.e., a decreasing of the surface resistance with increase of the temperature) is possible in double layer structures with thin superconductor and metal films.

A 200-mA, 93% peak power efficiency, single-inductor, dual-output DC–DC buck converter

A single-inductor dual-output (SIDO) DC---DC buck converter is presented. The circuit uses only one (external) inductor to provide two independent output voltages ranging from 1.2 V to the power supply (2.6---5 V) with a maximum total output current of 200 mA. The proposed converter has been fabricated in a 0.35-μm p-substrate CMOS technology. Measurement results demonstrate that a peak power efficiency as high as 93.3% can be achieved. An automatic substrate bias switch technique, that cancels the body effect of the p-channel output power transistors, improves the converter power efficiency performance.

Cost-effective sustain driver for alternating current plasma display panel

Cost-effective sustain driver for an alternating current (AC) plasma display panel (PDP) is proposed. It features a simple structure and low cost. As all power switches can be turned on with zero-voltage switching or turned off with zero-current switching, the switching losses can be reduced. An asymmetric current build-up scheme of the external inductor increases the flexibility in the rising time and the falling time of the panel voltage. Moreover, because sufficient energy is stored in the external inductors using build-up current, the voltage notch problem can be solved. The operation principle of the proposed circuit is presented in detail. A 32 inch AC PDP equipped with the proposed sustain driver is investigated.

DC Internal Inductance for a Conductor of Rectangular Cross Section

In this paper, the dc internal inductance for conductors with rectangular cross section is investigated. Using a quasistatic Green's function, the magnetic fields inside a rectangular conductor are derived. These magnetic field expressions are used to formulate the internal inductance of the conductor. We present numerical results and closed-form expressions for the dc internal inductance for this geometry. Comparisons to various expressions found in the literature are made, and the inaccuracies of these other results are presented and discussed. Finally, we discuss some of the subtleties associated with the inductance of a single current path, in which we examine why the total and external inductances of a single infinitely long conductor have no physical meaning, whereas the internal inductance does.

Expansion of a conducting shell by the magnetic field of an external inductor

The problem on magnetic field diffusion into the internal cavity of a hollow cylindrical conducting shell is solved analytically. In the case of an external field pulse representing a half-wave Be = Bmsin(πt/T), a region of the geometric parameters (thickness, diameter) is determined, for which the shell can be expanded under the action of the residual internal magnetic field.

Six‐band internal antenna for small‐size mobile phone

AbstractA promising six‐band internal antenna suitable for small‐size mobile phone application is presented. The mobile phone considered in this study has a system ground plane of length 60 mm only, much less than that of the general mobile phones. For such small‐size mobile phones, it is not easy for the embedded antenna to achieve a wide operating band at 900 MHz for GSM850/900 operation. The proposed antenna solved the problem with a reasonable occupied volume. The antenna mainly comprises three radiating elements of two longer monopoles and a shorter monopole, which are configured to occupy a volume of 3.6 cm3 only. The two longer monopoles incorporating an external parallel chip inductor lead to the successful excitation of a wide operating band for the antenna's lower band to cover GSM850/900 operation. Moreover, the three monopoles together contribute to the excitation of a very wide upper band to cover GSM1800/1900/UMTS/WLAN operation. That is, the antenna can perform six‐band operation for WWAN and WLAN communications. The proposed antenna is studied in detail in this article. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2242–2247, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23659

The investigation of giant magnetoimpedance effect in meander NiFe/Cu/NiFe film

In this paper, the meander NiFe/Cu/NiFe film is fabricated by MEMS technique and the giant magnetoimpedance (GMI) effects in both transverse and longitudinal directions are studied in the frequency range of 0.1–40 MHz. Upon increasing the magnetic field from 0 to 150 Oe, the effects in both directions show the single peak variation tendency, which is attributed to the deflection of anisotropy from the transverse direction. Compared with the GMI peak values of 11.2% and 3.0% in a longitudinal straight-line section, the GMI effects in meander structure are greatly improved and it could be up to 37% and 16.7% for the longitudinal and transverse results, respectively. The external inductance resulted from the meander shape is mainly responsible for the improvement.

Analysis, Design, and Implementation of a Parallel ZVS Converter

A soft-switching converter is presented in this paper to achieve a zero-voltage-switching (ZVS) turn on for all switches. Two half-bridge converters with asymmetric pulsewidth-modulation scheme are connected in parallel to control the output voltage at the desired value and achieve load-current sharing. Based on the output capacitance of power switches and the resonant inductance, including the external inductance and the transformer leakage inductance, the resonance can be achieved at the transition interval of power switches. Therefore, the ZVS turn on of power switches can be realized. The peak voltage of the power switches is limited to input dc voltage. The center-tapped rectifier is adopted at the transformer secondary side to achieve a full-wave rectification. Operation principles, steady-state analysis, and design equations of the proposed converter are discussed in detail. Finally, experimental results based on a 240-W prototype are provided to verify the performance and the feasibility of the proposed converter.

Two-port noise figure optimization of source-degenerated cascode CMOS LNAs

This paper presents a noise figure optimization technique for source-degenerated cascode CMOS LNAs with lossy gate inductors. The optimization technique, based on two-port theory, takes into account second order parasitic components. The effect of inductive source degeneration on LNA noise parameters is discussed. Measured noise figures agree well with the simulations confirming the accuracy of the noise model and allowing us to investigate the contributions of various components to the overall noise figure. A 0.18-μm CMOS LNA with an integrated inductor (Q = 7.5) achieves a noise figure of 1.16 dB and a return loss of 20 dB at 1.4 GHz, drawing 39 mA from a 1.8-V voltage supply, having gain (S 21) of 14.5 dB, input P1dB of ?17.5 dBm, and input IP3 of ?13 dBm. LNAs with external inductors having quality factor of Q = 170 and Q = 40 achieve noise figures of 0.65 dB and 0.68 dB and a return loss of 20 dB at 1.4 GHz, drawing 37 mA from a 1.8-V voltage supply, having gain (S 21) of 17 dB, input P1dB of ?22 dBm, and input IP3 of ?14 dBm. The large power consumption of the presented designs was intentionally selected in order to reduce the noise figure, an acceptable trade-off for LNA's targeted for radio telescope applications, and to assess the impact of the large currents flowing through interconnect metals on the noise figure

A Drive Circuit of Switched Reluctance Motors using Three-phase Power Modules

Switched Reluctance(SR) motors have several advantages for industrial applications. However, their drive circuits are not necessarily suitable. The drive circuit of a 3-phase SR motor has 6 switches and 6 diodes such as general 3-phase inverter, but its connection is different. So, a general 3-phase power module such as Intelligent Power Module(IPM) can't be used. We proposed a novel drive circuit for SR motors, which can be constructed using general a 3-phase power module without external inductors or devices. This drive method has several advantages including low cost, high efficiency, and compactness. It was simulated on SPICE including the controller and the driving performances were investigated. The new drive circuit allowed phase current to flow bi-directionally. So, the reluctance torque of SR motors is not affected by current direction. Then, we developed the new drive circuit for a 6/4 SR motor using a conventional 3-phase IPM. The results of the experiments indicated same performances as conventional way and higher efficiency than conventional way.

METHOD OF EDGE CURRENTS FOR CALCULATING MUTUAL EXTERNAL INDUCTANCE IN A MICROSTRIP STRUCTURE

Mutual external inductance (MEI) associated with fringing magnetic fields in planar transmission lines is a cause of so- called plane noise, which leads to radiation from printed circuit boards in high-speed electronic equipment. Herein, a Method of Edge Currents (MEC) is proposed for calculating the MEI associated with fringing magnetic fields that wrap the ground plane of a microstrip line. This method employs a quasi-magnetostatic approach and direct magnetic field integration, so the resultant MEI is frequency- independent. It is shown that when infinitely wide ground planes are cut to form ground planes of finite width, the residual surface currents on the tails that are cut off may be redistributed on the edges of the ground planes of finite thickness, forming edge currents. These edge currents shrink to filament currents when the thickness of the ground plane becomes negligible. It is shown that the mutual external inductance is determined by the magnetic flux produced by these edge currents, while the contributions to the magnetic flux by the currents from the signal trace and the finite-size ground plane completely compensate each other. This approach has been applied to estimating the mutual inductance for symmetrical and asymmetrical microstrip lines.