Showing papers on "Inductor published in 1995"

Equivalent-circuit model of the squeezed gas film in a silicon accelerometer

Abstract: We present a new electric equivalent circuit for the forces created by a squeezed gas film between vertically moving planar surfaces. The model is realized with frequency-dependent resistors and inductors. Circuit analysis tools are applied to calculate the response of a micromechanical silicon capacitive accelerometer in both the frequency and the time domains. The simulations are shown to match the measured frequency responses in an excellent way. We utilize the circuit model to calculate the effective viscosity in a narrow gap between the moving surfaces. The results are compared with different slip-flow equations discussed in the literature. We present a simple approximate equation of the pressure-dependent viscosity that is valid for both viscous and molecular damping regions, and has 5% accuracy.

Modeling and damping of high-frequency leakage currents in PWM inverter-fed AC motor drive systems

Abstract: This paper presents an equivalent circuit for high-frequency leakage currents in pulsewidth modulation (PWM) inverter-fed AC motors, which forms a series resonant circuit. The analysis based on the equivalent circuit leads to such a conclusion that the connection of a conventional common-mode choke or reactor in series between the AC terminals of a PWM inverter and those of an AC motor is not effective to reduce the rms and average values of the leakage current, but effective to reduce the peak value. Furthermore, this paper proposes a common-mode transformer which is different in damping principle from the conventional common-mode choke. It is shown theoretically and experimentally that the common-mode transformer is able to reduce the rms value of the leakage current to 25%, where the core used in the common-mode transformer is smaller than that of the conventional common-mode choke.

Low-noise voltage-controlled oscillators using enhanced LC-tanks

Abstract: Frequency synthesizers used in modern telecommunication systems, such as cellular telephones, need to have very low phase noise. Therefore, in the design of high performance frequency synthesizers using Phase Locked Loops (PLL), the Voltage-Controlled Oscillator (VCO) has become a key issue. The trend towards monolithic Integration poses some major challenges. This paper discusses the phase noise aspects of LC-tuned oscillators. A general formula is developed, based on the concepts of effective resistance and capacitance. The formula also applies for oscillators using active inductors. From these results the importance of an inductor with very low series resistance is apparent. To circumvent the technological limits given by an Inductor's series resistance, a presented enhanced LC-tank can be used to make a trade-off between noise and power.

Nonlinear-carrier control for high power factor boost rectifiers

Abstract: Novel nonlinear-carrier (NLC) controllers are proposed for high-power-factor boost rectifiers. In the NLC controllers, the switch duty ratio is determined by comparing a signal derived from the main switch current with a periodic, nonlinear carrier waveform. As a result, the average input current follows the input line voltage. The technique is suitable for boost power converters operating in the continuous conduction mode. Input voltage sensing, the error amplifier in the current-shaping loop, and the multiplier/divider circuitry in the voltage feedback loop are eliminated. The current-shaping is based on switch (as opposed to inductor) current sensing. The NLC controllers offer comparable or improved performance over existing schemes, and are well-suited for simple integrated-circuit implementation. Experimental verification on a 240 W rectifier is described. >

Parallel-connections of pulsewidth modulated inverters using current sharing reactors

Abstract: A technique of parallel connection of power devices by using current sharing reactors for pulsewidth modulated (PWM) inverters is reported in this paper. The proposed technique not only increases the current capacity but also decreases the output harmonic contents. The output voltage waveforms of the proposed inverter have certain voltage levels during their half cycles, thus it is anticipated that it will be difficult to analyze the output waveforms. For such waveforms, a frequency analysis approach is described, whose results are verified by experiments. >

Inductively powered lighting

Abstract: Disclosed is inductive coupling of power to devices having negative resistances, such as gas-filled discharge lamps (fluorescent tubes, neon signs, and the like) from a primary inductive loop, using resonant conditioning of the power provided to the device. A "C" shaped inductor (202) around the loop and a resonating capacitor (406) in parallel with the inductor provide a current source to the lamp (403) from across the capacitor. The circuit is capable of first igniting a lamp using a higher voltage available when the Q of the unloaded circuit is high, then running the lamp or other device at a controlled current. The lamp current is substantially proportional to the primary inductive loop flux, and substantially independent of the lamp resistance. A second inductor (404) in series with the first though not itself a collector of flux acts as a current limit. Applications include lighting, displays (optionally isolated and dimmable), and production of ultraviolet radiation.

Circuit topologies for PWM boost rectifiers operated from 1-phase and 3-phase AC supplies and using either single or split DC rail voltage outputs

Abstract: This paper provides a survey of PWM boost rectifier circuit topologies for controlling a nonisolated DC-rail voltage whilst drawing supply currents at a unity fundamental power factor and with a low total harmonic distortion. Rectifier-leg topologies are classified by the number of switches and by the PWM waveforms generated. Complete rectifier circuit topologies are described for operation off 1-phase and 3-phase AC supplies. Circuit analogies are made between rectifiers for 1 and 3 phases, rectifiers using either a single or a split DC-rail and between rectifiers using either AC or DC side inductors. The performances of the various circuits are assessed with reference to factors such as conduction losses, efficiency, switch count, semiconductor voltage stresses, 3-level and 2-level PWM voltage waveforms and, finally, bi-directional power conversion. >

A delta-configured auxiliary resonant snubber inverter

Abstract: A delta (/spl Delta/) configured auxiliary resonant snubber inverter is developed to overcome the voltage floating problem in a wye (Y) configured resonant snubber inverter. The proposed inverter is used to connect auxiliary resonant branches between phase outputs to avoid a floating point voltage which may cause overvoltage failure of the auxiliary switches. Each auxiliary branch consists of a resonant inductor and a reverse blocking auxiliary switch. Instead of using an anti-paralleled diode to allow resonant current to flow in the reverse direction, as in the Y-configured version, the resonant branch in the /spl Delta/-configured version must block the negative voltage, typically done by a series diode. This paper shows single-phase and three-phase versions of /spl Delta/-configured resonant snubber inverters and describes in detail the operating principle of a single-phase version. The extended three-phase version is proposed with nonadjacent state space vector modulation. For hardware implementation, a single-phase 1 kW unit and a three-phase 100 kW unit were built to prove the concept. Experimental results show the superiority of the proposed topology.

Planar microwave and millimeter-wave lumped elements and coupled-line filters using micro-machining techniques

Abstract: Planar microwave and millimeter-wave inductors and capacitors have been fabricated on high-resistivity silicon substrates using micro-machining techniques The inductors and capacitors are suspended on a thin dielectric membrane to reduce the parasitic capacitance to ground The resonant frequencies of a 12 nH and a 17-nH inductor have been increased from 22 GHz and 17 GHz to around 70 GHz and 50 GHz, respectively We also report on the design and measurement of a new class of stripline filters suspended on a thin dielectric membrane Interdigitated filters with 43% and 5% bandwidth have been fabricated and exhibit a port-to-port 07 dB and 20 dB loss, respectively, at 14-15 GHz The micro-machining fabrication technique can be used with silicon and GaAs substrates in microstrip or coplanar-waveguide configurations to result in planar low-loss lumped elements and filters suitable for monolithic integration or surface mount devices up to 100 GHz >

Air-gap reluctance and inductance calculations for magnetic circuits using a Schwarz-Christoffel transformation

Abstract: A method for calculating the reluctance of air gaps in magnetic circuits making use of a Schwarz-Christoffel transformation is described. The method is applied to the calculation of the inductance of example inductor and transformer configurations and its validity established through comparisons with calculations based on the finite-element method of numerical analysis. >

Monolithic passive component

Abstract: An integrated circuit having a monolithic device such as an inductor suspended over a pit in the substrate to reduce parasitic capacitances and enhance the self-resonant frequency of the inductor.

High efficiency electronic ballast for high intensity discharge lamps

Abstract: An electronic ballast is powered by power source (102) and (104). The ballast controls the electrical power supplied to a gas discharge lamp (116), providing the voltages and currents required to start, warm-up and operate the lamp (116). Line power conditioner (100) reduces interference and harmonic generation, and provides a source of DC power (103), which may be regulated. DC power (103) is applied to inverter (105), which generates a square-wave voltage at a variable frequency determined by control circuit (200). Inverter (105) output is connected to resonant circuit (600) consisting of series inductor (110), series capacitors (112) and (118), and parallel inductor (114), across which gas discharge lamp (116) is connected. Operation begins with inverter (105) running at a frequency initially near but above the unloaded series resonance frequency of resonant circuit (600). Controller (200) reduces the frequency until resonant circuit (600) gives sufficient voltage to start lamp (116). After lamp (116) starts, controller (200) increases inverter (105) frequency to an intermediate frequency near but above one-third of the resonance of the series inductor (110) and the capacitors ( 112) and (118 causing a high current to flow in lamp (116), for warm-up. After a warm-up interval, controller (200) further increases inverter (105) frequency to a final value which is also above the frequency of acoustic arc resonance and above the loaded resonance frequency of resonant circuit (600).

Introduction to modeling of transformers and coupled inductors

Abstract: A tutorial paper is presented on modeling and design of transformers and coupled inductors. Beginning with a brief review of electromagnetic laws and magnetic circuit models, the magnetic and electric models of transformers and coupled inductors are developed, including both magnetizing and leakage effects. It is shown that while the voltage waveforms on the windings are primarily related by the turns ratio for both devices, the winding currents of transformers and coupled inductors are determined by very different mechanisms. An integrated structure with both transformer and coupled inductor on the same core is also discussed, as well as the special case of the coupled inductor used on a multiple-output transformer-isolated converter. >

Modulation of the resonant frequency of a circuit using an energy field

Abstract: A transponder has a resonant RLC circuit with one or more electromagnetic energy storage components that vary in response to an externally applied modulating energy field. In addition to the externally modulating energy field, a base station transmits a carrier signal with a frequency essentially the same as the quiescent resonant frequency of the RLC circuit. As the component(s) vary, the resonant frequency of the RLC circuit changes, modulating the carrier signal with the external modulating energy field. Effects of the modulation are detected by the base station. Information (e.g., the presence of a tag) is obtained by receiving and demodulating the modulated signal at the base station. One or more of the circuit elements (e.g., different preferred embodiments of one or more capacitors, inductors, and resistors) can be varied (e.g. mechanically) to modulate the carrier signal. This allows the resonant circuit to modulate the carrier signal with multiple modulation frequencies to encode multiple bits of information on the carrier.

Multi-sectioned power converter having current-sharing controller

Abstract: An interleaved power converter is constructed so as to substantially equalize the power output of individual converter slices or phases. In an embodiment of the invention an interleaved power control system (110) includes a power bus (114) having a battery (116) coupled thereto and a plurality of slices (112) operating in a phased relationship with one another for causing the battery to source current to the power bus or to sink current from the power bus. Each of the slices includes an inductor (L) that is switchably coupled to the power bus and a controller (146) for controlling the switching of the inductor. The switching of the inductor is controlled as a function of (a) a difference between a magnitude of a voltage potential (VB) of the power bus and a predetermined voltage potential magnitude (Voltage Setpoint); (b) a difference between a magnitude of a current flowing through the power bus (IT) and a predetermined current magnitude (Charge Current Setpoint); and (c) a signal that indicates both of (i) a predetermined proportion of a total amount of current that the power converter system is supplying and, (ii) a magnitude of a peak current flowing through the inductor.

Flow sensor for an infusion pump

Abstract: An infusion pump for delivering a selected medication to a patient is provided with an inductance flow sensor for monitoring and verifying delivery of medication in response to pump operation The flow sensor comprises a compact inductor coil wrapped about a pump discharge conduit, in combination with a magnetically attractable core pin disposed within the discharge conduit for movement to a position within the inductor coil in response to pump outflow A control circuit operates with minimal power requirements to monitor coil inductance changes as a result of core pin displacement to confirm medication delivery to the patient in response to pump operation A magnet mounted at one end of the inductor coil draws and retains the core pin at a position retracted from the coil in the absence of pump outflow

Monolithic planar RF inductor and waveguide structures on silicon with performance comparable to those in GaAs MMIC

Abstract: The monolithic inductors and transmission lines on Si substrate with very high Q factor, low insertion loss, and high resonant frequency, are achieved by using very thick polyimide (10 /spl mu/m) as dielectric material, and thick Al (4 /spl mu/m) metalization system. This structure is made on the finished conventional standard two layer metalization BiCMOS wafer. For 10 nH inductor, 6 GHz resonant frequency, maximum Q factor of 5.5 at 1.2 GHz, and 1.2 dB insertion loss at 3 GHz are obtained, which are very comparable to those available in GaAs MMIC, These inductors can be used as RF choke as well as matching element. Transmission lines are also fabricated using this technology. The S/sub 21/ of coplanar waveguide with 1 mm length is -0.2 dB at 4 GHz, and that of microstrip line is -0.3 dB. It is expected that, using these passive elements, Si RF IC can be designed up to several GHz with performance comparable to GaAs MMIC.

Compact diplexer connection circuit

Abstract: A diplexer constructed on a stripline board includes a plurality of filters each having a series of filter sections providing an elongated physical configuration to the respective filter. Each filter section comprises an inductor and a capacitor. Each of the capacitors for each of the filters is formed in stripline format by laminating a pad of electrically conductive material to a sheet of electrically conductive material with the interposition of a layer of dielectric material between the pad and the sheet. Each inductor is formed as a coil wound about a core of air or solid magnetizable material. To provide for reduced physical size of the circuitry, thereby to accommodate emplacement of the circuitry within a television cable connection box, there is provided in a preferred embodiment of the invention filters of higher and lower frequency channels wherein the filter of the lower frequency channel has larger inductors. The lower frequency channel is bent to reduce overall size, the bending bringing distant inductors in close proximity. To reduce mutual coupling between the distant inductors, the inductors are arranged with mutually perpendicular orientations of their respective axes. Power combiners, power splitters, and relays are also included in the circuitry for provision of both incoming and outgoing telephony and television video signals.

Optimization of high Q integrated inductors for multi-level metal CMOS

Abstract: As the frequency standards for communication and other types of integrated circuits increase into the Gigahertz range, the use of integrated inductors becomes more and more feasible. Unfortunately, application of integrated inductors is hampered by a lack of design tools, and also useful models for how inductor properties vary with layout and how the inductor interacts with its environment. We discuss these issues and also analyze what we believe to be the optimal inductor layout for an unspecialized multi-layer metal submicron CMOS process. We conclude with a practical example of a 600 MHz communication circuit that can benefit from the availability of a good integrated inductor.

Multi-turn, multi-level IC inductor with crossovers

Abstract: A high value inductor with a high Q factor is formed using integrated circuit techniques to have a plurality of layers, where each layer has formed on it two or more coils. The coils in the various layers are interconnected in series. Although the resulting inductor exhibits a relatively high resistance, the number of coil turns is large. Since inductance increases in proportion to the square of the number of coil turns, the resulting inductor has a very high Q factor. A cross-over arrangement located in one level provides compact connections between turns in a different level.

Modelling winding losses in high-frequency power inductors

Abstract: A high-frequency model of iron-powder-core inductors is studied. The skin and proximity effects that cause the winding parasitic resistance to increase with the operating frequency are considered. The inductor self-resonance due to the parasitic capacitances is taken into account as well. The frequency response of the inductor model is compared to that of an experimentally tested iron-powder-core inductor. Expressions giving the ac resistance as a function of the operating frequency are given. These expressions allow for an accurate prediction of the inductor power loss over a wide frequency range. The measured and calculated values of the inductor impedance magnitude and phase, the real and imaginary parts of the inductor impedance, the inductance, and the inductor quality factor are plotted versus frequency and compared. Theoretical results were in good agreement with those experimentally measured. A design procedure for solid wire winding inductors based on the results of the inductor modelling is also given in the paper.

Method of making an electronic device having an integrated inductor

Abstract: An electronic device (10) comprises a copper integrated inductor (11) overlying other solid state components (31) of the device (10). Preferably, the copper inductor (11) is formed of plated copper to a thickness of several microns. The preferred integrated inductor (11) provides significant advantage over external inductors of the past with respect to simplicity of manufacture as well as system size and cost. Additionally, the preferred inductor (11) provides improved inductance per area, lower series resistance and higher Q values, relative to inductors of the past.

New, zero voltage switching, high frequency boost converter topology for power factor correction

Abstract: This paper introduces a technique for combining zero-voltage-switching with boost converter technology to enable high frequency, high efficiency operation of the converter. The combination creates a new topology which is effective to meet the power factor correction and harmonic reduction requirements of new EMC standards. The unique topology provides limitation of the recovery current of the boost diode and uses the energy recovered from the reverse current to discharge the intrinsic and stray capacitance of the boost switch while transferring this recovered energy to the output. With the main switching losses removed, the frequency can be increased to reduce the size of the boost inductor while maintaining continuous conduction mode operation for improved input noise filtering.

Compound inductors for use in switching regulators

Abstract: Compound inductors for use in switching regulators have two or more symmetrically coupled windings so the component size is reduced as well as a reduction in power losses compared with conventional inductors. The compound inductors may be used in buck and boost regulators. The compound inductor assembly has a first inductor with a first winding on a first magnetic core, a second inductor with a second magnetic core outside the first winding of the first inductor, and a second winding around the first winding of the first inductor and the second core. One end of the first winding and the corresponding end of the second winding is connected to a common connection such that voltages from an alternating current flowing in the first winding have the same polarity in the first winding and in the second winding.

Experimental study on spiral inductors

Abstract: An experimental study of spiral inductor loss is described quantitatively. For the evaluation of the loss, over one hundred types of spiral inductors with different figures (square, circle, octagon) and line/space widths are fabricated, then /spl pi/-network equivalent circuits are extracted from measured S-parameters. The results show that the resistance R of circular and octagonal shaped inductors is smaller by 10% than that of a square shaped inductor with the same inductance value. They also indicate that minimization of the line space is more effective for reducing the loss of the inductor with the same inductance value than maximization of the line width. >

An improved full-bridge zero-voltage switching PWM converter using a two-inductor rectifier

Abstract: An improved full-bridge ZVS PWM using a two- inductor rectifier dc/dc converter is presented in this paper. For this improved topology, the main devices are switched on under zero-voltage (ZVS) conditions using the energy stored in the secondary filter inductors. In addition, it utilizes the low leakage inductance of a coaxial winding transformer to reset the currents in the rectifier diodes and eliminate the secondary voltage spike. The two-inductor rectifier has only one diode conduction drop in addition to frequency doubling in the output capacitor. The secondary filter size in the proposed topology is rather small. The advantages of the new topology include a wide load range with ZVS, no lost duty cycle due to diode recovery, no secondary voltage spikes, in addition to high power density and high efficiency

Power supply with power factor correction circuit

Abstract: Disclosed is a power supply which includes a transformer having a primary winding and a secondary winding. A rectifier circuit rectifies an input AC mains signal to produce a DC rectified mains signal. A power factor correction circuit transfers electrical power from the rectifier circuit to the primary winding. A switch is provided for transferring electrical power from the primary winding to the secondary winding. The power factor correction circuit includes a first diode having an anode connected to the rectifier circuit and a cathode connected to one end of the primary winding and a second diode having an anode connected to the rectifier circuit and a cathode connected to said one end of the primary winding via a snubber network. The correction circuit may also include a third diode having an anode connected to the rectifier circuit and a cathode connected to a second end of the primary winding via an inductor.

Integrated planar magnetics and connector

Abstract: The present invention provides a magnetics substrate for implementing a coupled transformer and inductor. In one version, the transformer and inductor are used in a DC to DC converter. The transformer includes primary and secondary windings, each comprising a set of planar windings coupled to one another in series and lying on planar surfaces of layers of the magnetics substrate. These planar windings are coaxially aligned along a transformer core axis which is orthogonal to the layers, and the primary and secondary windings are magnetically coupled to one another through a transformer core positioned along the transformer core axis. The inductor includes a set of planar windings coupled to one another in series and lying on planar surfaces of the layers. These planar windings are coaxially aligned along an inductor core axis which is orthogonal to the layers and is spaced apart from the transformer core axis, and they are magnetically coupled to one another through an inductor core positioned along the inductor core axis. The magnetics substrate includes an interconnect coupling the secondary transformer winding to the inductor. It also includes terminal pads lying on a lower planar surface of the magnetics substrate and coupled to the inductor and the primary and secondary transformer windings. Each terminal pad is constructed to receive and couple to a conductive offset pin extending orthogonally from a terminal pad on an upper surface of a first substrate coupled to a first substrate circuit. The conductive offset pins position the magnetics substrate and the first substrate in a spaced apart parallel relationship and also couple the transformer and inductor to the circuit of the first substrate.

Low temperature co-fired ceramic substrates for power converters

Abstract: Electronic power conversion circuitry, for frequencies not exceeding 30 MHz, is manufactured using the benefits of low temperature co-fired ceramic substrates to provide interconnection between the discrete components of the power conversion circuit, and integrate various non-semiconductor devices into the body of the low temperature co-fired ceramic structure, such as resistors, capacitors, inductors and transformers. Use of a low temperature co-fired ceramic structure as a substrate on and within which power conversion circuitry is formed allows selection of various conductive and resistive inks to precisely form interconnection circuitry and selected non-semiconductor components which improves the stability and reduces the cost of power conversion circuits.