Showing papers on "Inductor published in 2001"

Performance improvements of interleaving VRMs with coupling inductors

Abstract: The multichannel interleaving buck converter with small inductance has proved to be suitable for voltage regulator modules (VRMs) with low voltages, high currents, and fast transients. Integrated magnetic components are used to reduce the size of the converter and improve efficiency. However, the structure of the integrated magnetic requires precise adjustment and is not mechanical stable. This paper proposes integrated coupling inductors between the channels to solve these problems. With the proper design, coupling inductors can improve both the steady-state and dynamic performances of VRMs with easier manufacturing.

Improved calculation of core loss with nonsinusoidal waveforms

Abstract: An extension to the Steinmetz equation is proposed, to enable estimation of hysteresis losses in magnetic core materials with nonsinusoidal flux waveforms The new formulation is shown to avoid anomalies present in previous modified-Steinmetz-equation calculations of loss with nonsinusoidal waveforms Comparison with experimental measurements in MnZn ferrite shows improved accuracy The result may be optionally formulated in terms of an effective frequency and an effective amplitude, and options for defining these are discussed

Stacked inductors and transformers in CMOS technology

Abstract: A modification of stacked spiral inductors increases the self-resonance frequency by 100% with no additional processing steps, yielding values of 5 to 266 nH and self-resonance frequencies of 11.2 to 0.5 GHz. Closed-form expressions predicting the self-resonance frequency with less than 5% error have also been developed. Stacked transformers are also introduced that achieve voltage gains of 1.8 to 3 at multigigahertz frequencies. The structures have been fabricated in standard digital CMOS technologies with four and five metal layers.

Computationally efficient winding loss calculation with multiple windings, arbitrary waveforms, and two-dimensional or three-dimensional field geometry

Abstract: The squared-field-derivative method for calculating eddy-current (proximity-effect) losses in round-wire or litz-wire transformer and inductor windings is derived. The method is capable of analyzing losses due to two-dimensional and three-dimensional field effects in multiple windings with arbitrary waveforms in each winding. It uses a simple set of numerical magnetostatic field calculations, which require orders of magnitude less computation time than numerical eddy-current solutions, to derive a frequency-independent matrix describing the transformer or inductor. This is combined with a second, independently calculated matrix, based on derivatives of winding currents, to compute total AC loss. Experiments confirm the accuracy of the method.

Analysis of current crowding effects in multiturn spiral inductors

Abstract: The effective trace resistance of a multiturn spiral inductor operating at high frequencies is known to increase dramatically above its dc value, due to proximity effect or current crowding. This phenomenon, which dominates resistance increases due to skin effect, is difficult to analyze precisely and has generally required electromagnetic simulation for quantitative assessment. Current crowding is studied in this paper through approximate analytical modeling, and first-order expressions are derived for predicting resistance as a function of frequency. The results are validated through comparisons with electromagnetic simulations and compared with measured data taken from a spiral inductor implemented in a silicon-on-sapphire process.

Steady-state analysis of the LLC series resonant converter

Abstract: The operating modes of the LLC series resonant converter are analyzed to determine the steady-state operating point and mode boundaries. The three-element LLC series resonant converter is realized by adding an inductor to the basic two-element series resonant converter topology. Unlike the two element series resonant converter, which is limited strictly to step down operation, the LLC converter is capable of both step up and step-down. A wide range of output power is controlled with only a narrow variation in operating frequency. In addition, zero-voltage switching can be achieved over the entire operating range. All of these desirable properties are obtained essentially for free, as the additional resonant inductor can be realized simply by introducing an air gap in the main power transformer.

A wireless batch sealed absolute capacitive pressure sensor

Abstract: This paper reports the development of an absolute wireless pressure sensor that consists of a capacitive sensor and a gold-electroplated planar coil. Applied pressure deflects a 6 μm-thin silicon diaphragm, changing the capacitance formed between it and a metal electrode supported on a glass substrate. The resonant frequency of the LC circuit formed by the capacitor and the inductor changes as the capacitance changes; this change is sensed remotely through inductive coupling, eliminating the need for wire connection or implanted telemetry circuits. The sensor is fabricated using the dissolved-wafer process and utilizes a boron-doped silicon diaphragm supported on an insulating glass substrate. The complete sensor measures 2.6 mm ×1.6 mm in size and incorporates a 24-turns gold-electroplated coil that has a measured inductance of 1.2 μH. The sensor is designed to provide a resonant frequency change in the range 95–103 MHz for a pressure change in the range 0–50 mmHg with respect to ambient pressure, providing a pressure responsivity and sensitivity of 160 kHz/mmHg and 1553 ppm/mmHg, respectively. The measured pressure responsivity and sensitivity of the fabricated device are 120 kHz/mmHg and 1579 ppm/mmHg, respectively.

Virtual ripple generation in switch-mode power supplies

Abstract: A system and method provides virtual ripple signal generation for use in voltage regulation applications. Some switch-mode power converters or voltage regulators use output signal ripple to effect voltage regulation. A virtual ripple generator provides this type of voltage regulator with a virtual ripple signal comprising an offset component responsive to actual load voltage, but with a generated AC ripple component of arbitrary magnitude that is independent of actual output signal ripple. Unlike the actual output ripple signal, the generated AC ripple component is not dependent on implementation specifics, such as circuit board layout or output capacitor ESR, and may have its gain set independent of the offset component. The generated AC ripple component is synchronized to the inductor switching actions of the voltage regulator and thus reflects actual inductor phase switching in single and multi-phase regulation applications. Virtual ripple signal generation can include output (load) voltage droop compensation.

High-Q LTCC-based passive library for wireless system-on-package (SOP) module development

Abstract: In this paper, we present the development and full characterization and modeling of a multilayer ceramic-based system-on-package component library. Compact high-Q three-dimensional inductor and capacitor topologies have been chosen and incorporated. A measured inductor Q factor as high as 100 and self-resonant frequency as high as 8 GHz have been demonstrated. The new vertically interdigitated capacitor topology occupies nearly an order of magnitude less of real estate while demonstrating comparable performance to the conventional topology. The low-temperature co-fired ceramic (LTCC) library has been incorporated into a 1.9-GHz CMOS power-amplifier design exhibiting a measured 17-dB gain, 26-dBm output power, and 48% power added efficiency. This power-amplifier module with fully integrated LTCC passives demonstrates a superior performance to those with full and partial on-chip passive integration.

Single-inductor multiple-output switching converters

Abstract: A family of single-inductor multiple-output switching power converters is presented. They can be classified into same-type, bipolar and mixed-type converters. Synchronous rectification and control loop design are discussed, and experimental and simulation results of representative converters are presented to verify the functionality of these converters.

Analysis of eddy-current losses over conductive substrates with applications to monolithic inductors and transformers

Abstract: In this paper, a closed-form integral representation for the eddy-current losses over a conductive substrate is presented. The results are applicable to monolithic inductors and transformers, especially when such structures are realized over an epitaxial CMOS substrate. The technique is verified against measured results from 100 MHz to 14 GHz for spiral inductors.

RF MEMS‐based tunable filters

Abstract: This paper overviews the application of RF MEMS switches in tunable filters as well as circuit developments for bandpass filters covering 110 MHz to 2.8 GHz. RF MEMS have several desirable features, including small size, low power requirements, and low loss. The basic operation of Raytheon's RF MEMS capacitive membrane switch is described. An overview of the technique used to integrate the switch into a variable capacitor structure with sixteen capacitance states is provided. Variable capacitor structures are used to construct multipole lumped bandpass filter designs, each with sixteen states. Finally, measured data from two representative five- and six-pole bandpass filters are presented. Characterization data demonstrates that the insertion loss for the five-pole filter using on-chip inductors was between 6.6 and 7.3 dB, and between 3.7 and 4.2 dB for the six-pole filter using off-chip inductors. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE11: 276-284, 2001.

Multiple power converter system using combining transformers

Abstract: Methods and circuitry for combining the outputs of multiphase power converters which greatly improves the transient response of the power conversion system are presented in a variety of embodiments. Transformers (e.g., 59, 60, 61, 62) may be used to accomplish the combining function, and with properly phased and connected windings it is possible to achieve a great reduction in output ripple current and a simultaneous reduction in transistor ripple current, which give the designer freedom to reduce the value of the system output inductor (e.g., 68), improving transient response.

Tunable lumped components with applications to reconfigurable MEMS filters

Abstract: This paper presents a novel design scheme for tunable coplanar waveguide components with applications to compact lumped-element MEMS reconfigurable filters. Shunt MEMS switches are employed for tuning the values of lumped components frequently encountered in microwave integrated circuits. In particular, shunt capacitors, series inductors and shunt inductive stubs are the main tunable circuit elements utilized in this work. Furthermore, accurate equivalent circuits that include the most important parasitics introduced by the tuning mechanism are provided. Finally, the proposed method is applied to the design and implementation of very compact low-pass and bandpass tunable filters. The very high tunability range, the compactness of the resulting networks and their very wideband response constitute the main advantages of this technique.

Buck-boost switching regulator

Abstract: A voltage regulator ( 1 ) and includes a first switch (S 1 ) coupled between an input conductor ( 2 ) and a first terminal ( 4 ) of an inductor ( 5 ), a second switch (S 2 ) coupled between the first terminal of the inductor and a common conductor ( 3 ), a third switch coupled between an output conductor ( 7 ) and a second terminal ( 6 ) of the inductor, and a fourth switch (S 4 ) coupled between the second terminal of the inductor and the common conductor ( 3 ). The voltage regulator is operated in a mixed buck-boost mode by producing a first signal (V 32 ) representative of the difference between an output voltage (V OUT ) produced on the output conductor ( 7 ) by the voltage regulator and a reference voltage. A second signal (I MEAS ) is produced to represent the current through the inductor ( 5 ). A third signal (V 68 ) is produced to represent a combination of the first signal and the second signal. A pulse width modulated error signal (PWM) is produced by comparing the third signal (V 68 ) to a reference voltage. The first (S 1 ) and fourth (S 4 ) switches are controlled in response to the error signal (PWM) and first (Q 23 ) and second (Q 27 ) state signals representative of prior states of the first (S 1 ) and fourth (S 4 ) switches.

AC resistance of planar power inductors and the quasidistributed gap technique

Abstract: Low-AC-resistance planar or foil-wound inductors constructed using a quasidistributed gap comprising multiple small gaps that approximate a distributed gap are analyzed. Finite-element simulations are used systematically to develop a model broadly applicable to the design of such quasidistributed gap inductors. It is shown that a good approximation of a distributed gap is realized if the ratio of gap pitch to spacing between gap and conductor is less than four, or if the gap pitch is comparable to a skin depth or smaller. Large gaps can reduce AC resistance, but for most practical designs gap length has little effect. A closed-form expression, which closely approximates the AC resistance factor for a wide range of designs, is developed. The methods are illustrated with an inductor for a high-ripple-current fast-response voltage regulator module (VRM) for microprocessor power delivery.

Sandwich-type ferromagnetic RF integrated inductor

Abstract: The first demonstration of a sandwich-type ferromagnetic RF integrated spiral inductor for the 2-GHz range is reported. Two ferromagnetic CoNbZr films were set to sandwich the spiral in order to enhance the amount of magnetic flux linkage across the coil current. The stresses given from the insulator to the ferromagnetic film were studied. The inductance L of 7.9 nH and the qualify factor Q of 12.7 were obtained for a 200 /spl mu/m/spl times/400 /spl mu/m size four-turn rectangular spiral at f=2 GHz. The inductance was better than that of an air core of the same coil size by 19%, and the Q was better by 23%. Comparison with the on-top magnetic film type was also discussed.

Multilayer thin-film MCM-D for the integration of high-performance RF and microwave circuits

Abstract: Thin-film multi-layer MCM-D technology using the system in a package concept is presented as a viable approach for the integration of high performance wireless front-end systems. Due to the high quality dielectrics and copper metallization, high quality transmission lines and inductors are available. This, together with the integrated passives design library containing scalable equivalent models for the inductors, capacitors, resistors, transmission lines and discontinuities, allows easy and accurate co-design between the passive and active devices. Examples of bandpass filters, power dividers, quadrature couplers, microwave feedthroughs, a DECT VCO and a 14 GHz LNA are given.

LLC series resonant DC-to-DC converter

Abstract: The present invention discloses a DC-to-DC converter. The DC-to-DC converter includes a square wave generator for generating a sequence of output voltages having a waveform of square wave. The DC-to-DC converter further includes a resonant tank connected to the square wave generator comprising a series capacitor connected to a series inductor and a parallel inductor. The DC-to-DC converter further includes a transformer having a primary side connected in series with the series inductor and connected in parallel to the parallel inductor. The transformer further includes a secondary side for connecting to a rectifying circuit for providing a rectified DC voltage to an output load circuit. The series capacitor functioning with the series inductor to provide a first characteristic resonant frequency represented by ƒ s , and the series capacitor functioning with the series inductor and the parallel inductor to provide a second characteristic resonant frequency represented by ƒ m wherein ƒ s >ƒ m . The converter runs at variable frequency switching to perform output regulation. The converter features high conversion efficiency at high input operation by switching at frequency between the first and second characteristic resonant frequency. In a preferred embodiment, the parallel inductor is integrated to transformer as primary magnetizing inductor and in further the series inductor may also be integrated into transformer.

Radio frequency identification tag on a single layer substrate

Abstract: A radio frequency identification (RFID) tag on a single layer substrate comprises a semiconductor integrated circuit RFID tag device and antenna circuit. A connection jumper may be used to bridge over the antenna circuit coil turns. The RFID tag device is located on the same side as an inductor coil and capacitor which forms a parallel resonant antenna circuit. The inductor coil has an inner end and an outer end. The inner or outer end may be connected directly to the RFID tag device and the outer or inner end be may connected to the RFID tag device with a jumper over the inductor coil turns, or the RFID tag device may bridge the inductor coil turns when being connected to both the inner and outer ends. An encapsulation (glop top) may be used to seal the RFID tag device and jumper, and an insulated coating may be used to cover the entire surface of the substrate to create an inexpensive “chip-on-tag.” The encapsulation may be epoxy, plastic or any protective material known to one of ordinary skill in the art of electronic circuit encapsulation. The insulated coating may be of any type suitable for the application of use of the RFID tag.

Soft-switched full-bridge converters

Abstract: A family of soft-switched, full-bridge pulse-width-modulated (FB PWM) converters provides zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this family achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing two magnetic components whose volt-second products change in the opposite directions with a change in phase shift between the two bridge legs. One magnetic component always operates as a transformer, where the other magnetic component can either be a coupled inductor, or uncoupled (single-winding) inductor. The transformer is used to provide isolated output(s), whereas the inductor is used to store the energy for ZVS.

Method and apparatus for sensing output inductor current in a dc-to-dc power converter

Abstract: A current sense circuit for a DC-to-DC power converter accurately senses the output inductor current without adversely affecting efficiency of the power converter. The current sense circuit produces a current sense signal having amplitude sufficiently above the noise floor so that accurate load control of the power converter is achieved. Specifically, the DC-to-DC power converter includes at least one power switch connected to an input voltage source. At least one phase sensing switch is connected to the input voltage source in parallel with the at least one power switch. A pulse width modulation circuit provides common control pulses for the at least one power switch and the at least one phase sensing switch responsive to a current sense signal. An output inductor is connected to the at least one power switch and to a load. A current sensor is coupled to the output inductor and providing the current sense signal to the pulse width modulation circuit corresponding to current passing through an internal DC resistance of the output inductor. The current sensor further includes a filter that includes an on-state resistance of the at least one power switch. The current sensor further includes a second filter adapted to remove noise from the current sense signal when the at least one phase sensing switch and the at least one power switch change state.

Magnetic bead-based arrays

Abstract: The present invention relates to magnetic particle separators using micromachined magnetic arrays and more particularly, to magnetic particle separators or manipulators using controlled magnetization on micromachined magnetic arrays for the separation of cells and other biological materials. The present invention also pertains to using such devices for the separation and analysis of biological materials for immunoassays, DNA sequencing, protein analysis, and biochemical detection applications. The present invention can also be viewed as a novel method for fabricating fully integrated permanent magnet components within any microelectromechanical system (“MEMS”) structures. The present invention also provides a magnetic particle separation and manipulation system for rapid separation and accurate manipulation of magnetic particles in two-dimensional electromagnetic arrays, which utilize high throughput biological analyses. A disposable cartridge can be produced in low cost using a low cost substrate such as plastic or other polymer, glass, or metal. Magnetic flux is generated by conventional or micromachined electromagnets a platform system consisting of magnetic flux sources, magnetic flux guidance, and a microprocessor control interface. By controlling direction of electric currents into inductors on the platform system, arbitrary magnetic poles can be generated on Permalloy structures of the cartridge to separate and manipulate magnetic particles. The magnetic particle separator and manipulator in the present invention can be easily combined with automated detection systems such as a fluorescent monitoring system.

Thin film bulk acoustic resonator (FBAR) and inductor on a monolithic substrate and method of fabricating the same

Abstract: An apparatus having both a resonator and an inductor fabricated on a single substrate and a method of fabricating the apparatus are disclosed. The apparatus includes a resonator and an inductor that is connected to the resonator. Both the resonator and the inductor are fabricated over their respective cavities to produce a high Q-factor filter circuit.

High-performance inductors

Abstract: In this paper, we describe the design, test data, and analysis of several circular spiral inductors fabricated on GaAs substrates using the multifunction self-aligned gate multilayer process. Various factors such as high inductance, high-quality and, high current handling capacity, and compactness are studied. Several configurations for inductors were investigated to optimize the inductor geometry such as the linewidth, spacing between the turns, conductor thickness, and inner diameter. It includes measured effects of various parameters on inductor performance, such as linewidth, spacing, inner diameter, metal thickness, underlying dielectric, and dielectric thickness. It is shown experimentally that the Q factor of spiral inductors can be enhanced by using 9-/spl mu/m-thick metallization and placing inductors on a 10-/spl mu/m-thick polyimide layer, which is placed on top of the GaAs substrate. Using this technique, we have observed up to 93% improvement in the Q factor of circular spiral inductors, as compared to standard spiral inductors fabricated on GaAs substrates. Inductors having thick metallization can also handle dc currents as large as 0.6 A.

Symmetrical DC/DC converter

Abstract: A symmetrical DC/DC converter selects an energy transferring direction and a step-up or a step-down operation as well as a desired step-up or a step-down ratio. The converter includes a single inductor with a pair of switching devices connected to its terminals in a symmetrical arrangement with respect to the inductor. The converter is operable as a step-up converter and a step-down converter in a manner such that one and the other of the switching devices are used as an input switch and an output switch, respectively, and that one and the other of the switching devices are conversely used as an output switch and an input switch, respectively.

Method And Apparatus For Receiving A Universal Input Voltage In A Welding Power Source

Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.

Single switch electronic dimming ballast

Abstract: An electronic ballast for driving at least one gas discharge lamp from a source of AC power which has a substantially sinusoidal line voltage at a given line frequency. The ballast includes a rectifying circuit having AC input terminals and DC output terminals, the AC input terminals connectable to the source of AC power, the rectifying circuit producing a rectified output voltage at its the DC output terminals when the AC input terminals are energized by the source of AC power; a valley fill circuit having input and output terminals; the input terminals of the valley fill circuit connected to the DC output terminals of the rectifying circuit; an inverter circuit having input terminals and output terminals; the input terminals of the inverter circuit connected to the output terminals of the valley fill circuit and the output terminals of the inverter circuit connectable to the at least one gas discharge lamp and producing a high frequency drive voltage for driving a lamp current through the at least one gas discharge lamp when the AC input terminals are energized by the source of AC power. The inverter circuit has a single controllably conductive device and an inductor; the inductor connectable to the at least one gas discharge lamp; the inverter circuit being adapted to draw current from the source of AC power whereby the total current drawn from the source of AC power has a total harmonic distortion below about 33.3%; and whereby the lamp current has a current crest factor below about 2.1.

Planar inductors and method of manufacturing thereof

Abstract: A printed circuit board has two layers of printed circuit board dielectric material; a core made of ferromagnetic material between the two layers; and conductive leads on the opposite side of each dielectric layer from the core connected by via holes through both dielectric layers to form a conducting coil around the core. The conductive leads can form two separate coils around the core to form a transformer. A planar conducing sheet can be placed on or between one or more of the printed circuit board's dielectric layers to shield other circuitry on the printed circuit board from magnetic fields generated around the core. The core can be formed at least in part by electroless plating. Electroplating can be used to add a thicker layer of less conductive ferromagnetic material. Ferromagnetic inductive cores can be formed on the surface of a dielectric material by: dipping the surface of the dielectric in a solution containing catalytic metal particles having a slight dipole; and placing the dielectric in a metal salt to cause a layer containing metal to be electrolessly plated upon the dielectric. Plasma etching or other technique can be used before the dipping process to roughen the dielectric's surface to help attract the catalytic particles. This method can be used to form an inductor core on or between one or more dielectric layers of a printed circuit board, of a multichip module, of an integrated circuit, or of a micro-electromechanical device.

Design of a magnetic-pole enhanced inductively coupled plasma source

Abstract: The trend towards large-area substrates stressed by the semiconductor and flat panel display (FPD) industries is propelling the large-area plasma source developments. In this work, a novel inductively coupled plasma source enabling large-area plasma production is presented: the magnetic-pole-enhanced inductively coupled plasma source (MaPE-ICP). The plasma source is based on the use of a coil inductor embedded within a high magnetic permeability pole to enhance the magnetic coupling between the coil and the plasma. A 200 mm MaPE-ICP source has been fully characterized by Langmuir probe, magnetic induction probe and RF electrical parameter measurements. The plasma characteristics are compared to classical ICP source performances. RF electrical parameter measurements show that the current needed to sustain the plasma is halved with the use of a magnetic pole, thus lowering the coil resistive losses. The plasma uniformity is improved compared to that of a spiral coil source, with only a 5.5% variation within the area of the coil radius at 5 mTorr argon pressure. Preliminary plasma uniformity measurements carried out on a 800 mm×800 mm source show that a non-uniformity of 20% from the average values is achieved over 600 mm with more than 1011 ion cm-3. This demonstrates that the use of a magnetic pole to concentrate the magnetic flux is a key asset for scaling up ICPs.