Showing papers on "Inductor published in 2006"

Analytical loss model of power MOSFET

Abstract: An accurate analytical model is proposed in this paper to calculate the power loss of a metal-oxide semiconductor field-effect transistor. The nonlinearity of the capacitors of the devices and the parasitic inductance in the circuit, such as the source inductor shared by the power stage and driver loop, the drain inductor, etc., are considered in the model. In addition, the ringing is always observed in the switching power supply, which is ignored in the traditional loss model. In this paper, the ringing loss is analyzed in a simple way with a clear physical meaning. Based on this model, the circuit power loss could be accurately predicted. Experimental results are provided to verify the model. The simulation results match the experimental results very well, even at 2-MHz switching frequency.

Shielded passive devices for silicon-based monolithic microwave and millimeter-wave integrated circuits

Abstract: This paper introduces floating shields for on-chip transmission lines, inductors, and transformers implemented in production silicon CMOS or BiCMOS technologies. The shield minimizes losses without requiring an explicit on-chip ground connection. Experimental measurements demonstrate Q-factor ranging from 25 to 35 between 15 and 40 GHz for shielded coplanar waveguide fabricated on 10 /spl Omega//spl middot/cm silicon. This is more than a factor of 2 improvement over conventional on-chip transmission lines (e.g., microstrip, CPW). A floating-shielded, differentially driven 7.4-nH inductor demonstrates a peak Q of 32, which is 35% higher than an unshielded example. Similar results are realizable for on-chip transformers. Floating-shielded bond-pads with 15% less parasitic capacitance and over 60% higher shunt equivalent resistance compared to conventional shielded bondpads are also described. Implementation of floating shields is compatible with current and projected design constraints for production deep-submicron silicon technologies without process modifications. Application examples of floating-shielded passives implemented in a 0.18-/spl mu/m SiGe-BiCMOS are presented, including a 21-26-GHz power amplifier with 23-dBm output at 20% PAE (at 22 GHz), and a 17-GHz WLAN image-reject receiver MMIC which dissipates less than 65 mW from a 2-V supply.

A Digital Current-Mode Control Technique for DC–DC Converters

Abstract: The objective of this paper is to propose a simple digital current mode control technique for dc-dc converters. In the proposed current-mode control method, the inductor current is sampled only once in a switching period. A compensating ramp is used in the modulator to determine the switching instant. The slope of the compensating ramp is determined analytically from the steady-state stability condition. The proposed digital current-mode control is not predictive, therefore the trajectory of the inductor current during the switching period is not estimated in this method, and as a result the computational burden on the digital controller is significantly reduced. It therefore effectively increases the maximum switching frequency of the converter when a particular digital signal processor is used to implement the control algorithm. It is shown that the proposed digital method is versatile enough to implement any one of the average, peak, and valley current mode controls by adjustment of the sampling instant of the inductor current with respect to the turn-on instant of the switch. The proposed digital current-mode control algorithm is tested on a 12-V input and 1.5-V, 7-A output buck converter switched at 100kHz and experimental results are presented

Band stop filter employing a capacitor and an inductor tank circuit to enhance MRI compatibility of active medical devices

Abstract: A band stop filter is provided for a lead wire of an active medical device (AMD). The band stop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the band stop filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the band stop filter is integrated into a TIP and/or RING electrode for an active implantable medical device.

A high efficiency, soft switching DC-DC converter with adaptive current-ripple control for portable applications

Abstract: A novel control scheme for improving the power efficiency of low-voltage dc-dc converters for battery-powered, portable applications is presented. In such applications, light-load efficiency is crucial for extending battery life, since mobile devices operate in stand-by mode for most of the time. The proposed technique adaptively reduces the inductor current ripple with decreasing load current while soft switching the converter to also reduce switching losses, thereby significantly improving light-load efficiency and therefore extending the operation life of battery-powered devices. A load-dependent, mode-hopping strategy is employed to maintain high efficiency over a wide load range. Hysteretic (sliding-mode) control with user programmable hysteresis is implemented to adaptively regulate the current ripple and therefore optimize conduction and switching losses. Experimental results show that for a 1-A, 5- to 1.8-V buck regulator, the proposed technique achieved 5% power efficiency improvement (from 72% to 77%) at 100 mA of load current and a 1.5% improvement (from 84% to 85.5%) at 300 mA, which constitute light-load efficiency improvements, when compared to the best reported, state-of-the-art techniques. As a result, the battery life in a typical digital signal processing microprocessor application is improved by 7%, which demonstrates the effectiveness of the proposed solution.

High-Power Density Design of a Soft-Switching High-Power Bidirectional DC-DC Converter

Abstract: A typical non-isolated bi-directional dc-dc converter technology is to combine a buck converter and a boost converter in a half-bridge configuration. In order to have high-power density, the converter can be designed to operate in discontinuous conducting mode (DCM) such that the passive inductor can be minimized. The DCM associated current ripple can be alleviated by multiphase interleaved operation. However DCM operation tends to increase turn-off loss because of a high peak current and its associated parasitic ringing due to the oscillation between the inductor and the device output capacitance. Thus the efficiency is suffered with the conventional DCM operation. Although to reduce the turn-off loss, a lossless capacitor snubber can be added across the switch, the energy stored in the capacitor needs to be discharged before device is turned on in order to realize zero-voltage switching. This paper adopts a gate signal complimentary control scheme to turn on the non-active switch and divert the current into the anti-paralleled diode of the active switch so that the main switch can turn on under zero-voltage condition. Thus both soft switching turn-on and turn-off are achieved. This diverted current also eliminates the parasitic ringing in inductor current. For capacitor value selection, there is a trade-off between turn-on and turn-off losses. This paper suggests the optimization of capacitance selection through a series of hardware experiments to ensure the overall power loss minimization under complimentary DCM operating condition. A 100kW hardware prototype is constructed and tested. The experimental results are provided to verify the proposed design approach.

A Wide Tuning-Range CMOS VCO With a Differential Tunable Active Inductor

Abstract: By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-mum CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from -101 to -118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of 150times300 mum2

Piezoelectric Energy Harvesting using a Synchronized Switch Technique

Abstract: This article describes a new approach to harvest electrical energy from a mechanically excited structure equipped with piezoelectric elements. Standard harvesting circuits using piezoelectric elements as an electric generator consist of an AC-DC converter coupled to a load. The technique proposed herein is fully compatible with the standard approach. The difference consists in adding up an electrical switching device connected in parallel with the piezoelectric elements. The switch device is triggered on the maxima or minima of the displacement and realizes a voltage inversion through an inductor. This method allows the artificial increase of the piezoelements' output voltage, resulting in a significant increase of the electrical power flow. It is shown that the power flow transfer strongly depends on the structure electromechanical coupling coefficient. For a weakly coupled structure using this new technique, the electrical power can be increased by over 400%.

Design Considerations for Very High Frequency dc-dc Converters

Abstract: This document describes several aspects relating to the design of dc-dc converters operating at frequencies in the VHF range (30–300 MHz). Design considerations are treated in the context of a dc-dc converter operating at a switching frequency of 100 MHz. Gate drive, rectifier and control designs are explored in detail, and experimental measurements of the complete converter are presented that verify the design approach. The gate drive, a self-oscillating multi-resonant circuit, dramatically reduces the gating power while ensuring fast on-off transitions of the semiconductor switch. The rectifier is a resonant topology that absorbs diode parasitic capacitance and is designed to appear resistive at the switching frequency. The small sizes of the energy storage elements (inductors and capacitors) in this circuit permit rapid start-up and shut-down and a correspondingly high control bandwidth. These characteristics are exploited in a high bandwidth hysteretic control scheme that modulates the converter on and off at frequencies as high as 200 kHz.

Boost current multilevel inverter and its application on single-phase grid-connected photovoltaic systems

Abstract: This work presents a novel current multilevel (CML) inverter topology, named boost CML inverter, and its application on energy processing of single-phase grid-connected photovoltaic (PV) systems. The structure allows a high power factor operation of a PV system, injecting a quasi-sinusoidal current into the grid, with virtually no displacement in relation to the line voltage at the point of common coupling among the PV system and the loads. The major appeals of using the CML technique are the balanced current sharing among semiconductor switches and the decrease of the current slope in the circuit devices, with a consequent reduction of conducted and radiated electromagnetic interference (EMI). The CML technique also allows adapting or minimizing current waveforms harmonic content. System description, mathematical approach, and design guidelines are presented, providing an overview of the new topology. In order to validate the proposed concepts, experimental measurements, made in a small-scale laboratory prototype, are also presented. The obtained results evidence the feasibility of the application of this new topology on singlephase grid-connected PV systems.

Frequency-dependent resistance in Litz-wire planar windings for domestic induction heating appliances

Abstract: In this paper, the frequency-dependent resistance in Litz-wire planar windings for domestic induction heating appliances is analyzed. For these inductors, in which the size is not an essential constraint, an analytical model is developed based on the superposition of different loss effects in the wire. Eddy current losses, including conduction losses and proximity-effect losses, both internal and external, were considered and modeled. The magnetic field necessary to evaluate the external proximity losses is as well analytically calculated considering the complete winding and load properties. To verify this model and its limitations, several inductors with different wires and numbers of turns were constructed and results with both non-loaded and loaded inductors are compared with theoretical predictions.

DC-Link Stabilization and Voltage Sag Ride-Through of Inverter Drives

Abstract: Previous results concerning instability of the dc link in inverter drives fed from a dc grid or via a rectifier are extended. It is shown that rectifier-inverter drives equipped with small (film) dc-link capacitors may need active stabilization. The impact of limited bandwidth and switching frequency in the inverter-motor current control loop is considered, and recommendations for selection of the dc-link capacitor, the switching frequency, and the dc-link stabilization control law in relation to each other are given. This control law is incorporated in a field-weakening (to enhance voltage sag ride-through) current controller for which design recommendations are presented

Switched resonators and their applications in a dual-band monolithic CMOS LC-tuned VCO

Abstract: A switched resonator concept, which can be used to reduce the size of multiple-band RF systems and which allows better tradeoff between phase noise and power consumption, is demonstrated using a dual-band voltage-controlled oscillator (VCO) in a 0.18-/spl mu/m CMOS process. To maximize Q of the switched resonator when the switch is on, the mutual inductance between the inductors should be kept low and the switch transistor size should be optimized. The Q factor of switched resonators is /spl sim/30% lower than that of a standalone inductor. The dual-band VCO operates near 900 MHz and 1.8 GHz with phase noise of -125 and -123dBc/Hz at a 600-kHz offset and 16-mW power consumption. Compared to a single-band 1.8-GHz VCO, the dual-band VCO has almost the same phase noise and power consumption, while occupying /spl sim/37% smaller area.

Analysis and Design of High Efficiency Matching Networks

Abstract: This letter presents analysis and design considerations for lumped (inductor and capacitor) matching networks operating at high efficiency (>95%). Formulas for calculating matching network efficiency are given, and it is shown that efficiency can be expressed as a function of inductor quality factor QL, capacitor quality factor QC , and transformation ratio. These formulas are used to evaluate the optimum number of L-section matching stages as a function of conversion ratio. Both simulation and experimental results are presented that validate the analytical formulation

Method and Apparatus of Providing Power to Ignite and Sustain a Plasma in a Reactive Gas Generator

Abstract: According to a first aspect, a power supply and a method of providing power for igniting a plasma in a reactive gas generator is provided that includes (i) coupling a series resonant circuit (100) that comprises a resonant inductor (110) and a resonant capacitor (120) between a switching power source (60) and a transformer (30), the transformer having a transformer primary (32) and a plasma secondary (36); (ii) providing a substantially resonant AC voltage from the resonant capacitor across the transformer primary, thereby inducing a substantially resonant current within the transformer primary to generate the plasma secondary; and (iii) upon generation of the plasma secondary, the resonant inductor limiting current flowing to the switching power supply. According to another aspect, bipolar high voltage ignition electrodes can be used in conjunction with inductive energy coupling to aid in plasma ignition.

High-efficiency Voltage-clamped DC-DC converter with reduced reverse-recovery current and switch-Voltage stress

Abstract: This paper investigates a high-efficiency clamped-voltage dc-dc converter with reduced reverse-recovery current and switch-voltage stress. In the circuit topology, it is designed by way of the combination of inductor and transformer to increase the corresponding voltage gain. Moreover, one additional inductor provides the reverse-current path of the transformer to enhance the utility rate of magnetic core. In addition, the voltage-clamped technology is used to reduce the switch-voltage stress so that it can select the Schottky diode in the output terminal for alleviating the reverse-recovery current and decreasing the switching and conduction losses. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage-drift problem of power source under the variation of loads. Thus, the proposed converter topology has a favorable voltage-clamped effect and superior conversion efficiency. Some experimental results via an example of a proton-exchange-membrane fuel cell (PEMFC) power source with a 250-W nominal rating are given to demonstrate the effectiveness of the proposed power-conversion strategy.

Inductively Compensated Parallel Coupled Microstrip Lines and Their Applications

Abstract: A simple method using lumped inductors to compensate unequal even- and odd-mode phase velocities in parallel coupled microstrip lines is presented. The singly and doubly compensated cases are analyzed to enable the optimum inductor values and the electrical lengths of the compensated coupled lines to be calculated from closed-form expressions. The technique proposed not only improves the performance, but also yields a more compact design. To demonstrate the technique's broad range of applicability, the compensated coupled-line structure is used to enhance the performance of a 900-MHz Lange coupler, a 1-GHz multisection 10-dB coupler, a 900-MHz planar Marchand balun, and a 1.8-GHz parallel coupled bandpass filter

Parasitic capacitance cancellation in filter inductors

Abstract: This paper introduces a technique for improving the high-frequency performance of filter inductors and common-mode chokes by cancelling out the effects of parasitic capacitance. This technique uses additional passive components to inject a compensation current that cancels the parasitic current, thereby improving high-frequency filtering performance. Two implementation approaches for this technique are introduced. The first implementation achieves cancellation using an additional small winding on the filter inductor and a small capacitor. This approach is effective where very high coupling of the windings can be achieved or where only moderate performance improvements are required. The second implementation utilizes a small radio frequency transformer in parallel with the filter inductor to inject cancellation currents from the compensation capacitor. This technique requires an additional component (the transformer), but can provide a high degree of cancellation. Experimental results confirm the theory in both implementations.

Low energy dissipation electric circuit for energy harvesting

Abstract: A low energy dissipation circuit is proposed to achieve more effective energy harvesting, called 'synchronized switch harvesting on inductor (SSHI)'. The proposed circuit only has two diodes, while the original SSHI circuit has four diodes comprising a diode bridge. It thus reduces the voltage drop during the energy-harvesting process, because the actual diodes have forward voltage regarded as equivalent electrical resistance or energy dissipation. Energy-harvesting experiments demonstrated that the proposed circuit increases the harvested energy output to as much as 120% of that for the original SSHI circuit. We confirmed that the storage voltage in the steady state is independent of the storage capacitance through extensive energy-harvesting experiments, and that the settling time of the storage voltage is proportional to the storage capacitance but independent of the harvesting circuit.

Variable frequency current-mode control for switched step up-step down regulators

Abstract: A switched regulator circuit provides step-up and step-down operation in which the level of the input voltage can be greater, equal to, or less than a preset controlled output voltage. A four switch arrangement or two switch arrangement provides buck, boost, and buck-boost regulation under variable frequency valley-peak current mode control. A single sense resistor may be utilized for sensing inductor current during each duty cycle.

Design of Inductor Winding Capacitance Cancellation for EMI Suppression

Abstract: In this paper, the parasitics in both differential-mode (DM) and common-mode (CM) inductors are first discussed. The methods for both DM and CM inductor winding capacitance cancellation are then proposed. Prototypes are designed and tested, using a network analyzer. Finally, the prototypes are applied to practical power converters and electromagnetic interference (EMI) is measured. Both small signal measurement and practical EMI measurement prove that the proposed methods can efficiently reduce the effects of winding capacitance and therefore improve the inductor's filtering performance

Limitations of the Simulated Inductors Based on a Single Current Conveyor

Abstract: In this paper, a new simulated inductor employing two resistors, one capacitor, and only a single gain-variable third-generation current conveyor (GVCCIII) is proposed. To exhibit the performance of the proposed simulated inductor, it is used in a parallel R-L-C current-mode filter. The frequency-dependent nonideal voltage gain effects of the GVCCIII on the proposed inductor are given. The low- and high-frequency limitations of the simulated inductor are investigated in detail. The simulations performed with the SPICE program agree with the theoretical analysis. Also, the proposed circuit is tested experimentally using commercially available active devices (AD844 ICs of Analog Devices) to confirm the theory

Fully digital hysteresis modulation with switching-time prediction

Abstract: This paper proposes a digital hysteresis-modulation technique based on switching-time prediction. Sampling controlled variables several times within a switching period, it ensures a dynamic performance comparable to that obtainable with analog hysteresis modulation. Compared to conventional digital hysteresis modulation, it avoids frequency jitter since it predicts switching transitions. Compared to hysteresis modulation based on the detection of the zero crossing of current errors, it avoids external analog circuits. Compared to pulsewidth-modulation (PWM) techniques, it ensures faster dynamic response. These advantages are obtained at the expense of increased signal-processing requirements and of control complexity. Switching-frequency stabilization and synchronization with an external clock can be obtained extending the techniques proposed for analog hysteresis modulations. The proposed predictive algorithm does not require knowledge of load parameters and only a rough estimation of the inductor value, which can be easily self-adjusted. The proposed solution is suited for high-performance current (or sliding-mode) control where the digital hardware has enough computational power to allow multiple samples within a switching period. The proposed modulation technique has been applied to a sliding-mode control of a single-phase uninterruptible power supply (UPS). Experimental results confirm the effectiveness of the proposed approach.

Multiphase voltage regulator having coupled inductors with reduced winding resistance

Abstract: A multiple phase buck converter or boost converter, or buck-boost converter has an inductor in each phase. The inductors are inversely coupled. In a first embodiment, the converter includes a toroidal magnetic core with inductors extending under and over opposite sides of the toroidal magnetic core. The coupled inductors are thereby inversely coupled and have a relatively low ohmic resistance. In a second embodiment, the converter comprises a ladder-shaped magnetic core (i.e. having parallel sides, and connecting rungs). In this case, the inductors extend under the sides, and over the rungs. Each inductor is disposed over a separate rung. The ladder-shaped magnetic core is preferably disposed flat on a circuit board. Inverse coupling and low ohmic resistance are also provided in the second embodiment having the ladder structure.

Multiphase DC to DC converter

Abstract: A multiphase DC to DC converter (100) includes an input (Vin), an output (Vout), at least first and second converters (104, 106), an inductor (L), an output capacitor (C), and a drive circuit The drive circuit is configured for switching the first and second converters (104, 106) with a predetermined phase shift therebetween The output capacitor (C) is operatively coupled between the first and secon converters (104, 106) and the output (Vout) The inductor (L) can be placed either at the input side or the output side When placed at the input side, the inductor (L) is operatively coupled between an input capacitor and the first and second converters When placed at the output side, the inductor is operatively coupled between the first and second converters and the output capacitor (C) The multiphase DC to DC converter is capable of achieving lossless switching transitions and negligible ripple current in the output capacitor (C)

Multimodal vibration damping through piezoelectric patches and optimal resonant shunt circuits

Abstract: Piezoelectric elements connected to shunt circuits and bonded to a mechanical structure form a dissipation device that can be designed to add damping to the mechanical system. Due to the piezoelectric effect, part of the vibration energy is transformed into electrical energy that can be conveniently dissipated. Therefore, by using appropriate electrical circuits, it is possible to dissipate strain energy and, as a consequence, vibration is suppressed through the added passive damping. From the electrical point of view, the piezoelectric element behaves like a capacitor in series with a controlled voltage source and the shunt circuit, commonly formed by an RL network, is tuned to dissipate the electrical energy, more efficiently in a given frequency band. It is important to know that large inductances are frequently required, leading to the necessity of using synthetic inductors (obtained from operational amplifiers). From the mechanical point of view, the vibration energy can be attenuated in a single mode, or in multiple modes, according to the design of the damping device and the frequency band of interest. This work is devoted to the study of passive damping systems for single modes or multiple modes, based on piezoelectric patches and resonant shunt circuits. The present contribution discusses the modeling of piezoelectric patches coupled to shunt circuits, where the basics of resonant shunt circuits (series and parallel topologies) are presented. Following, the devices used in passive control (piezoelectric patch and synthetic inductors) are analyzed from the electrical and experimental viewpoints. The modeling of multi-degree-of-freedom mechanical systems, including the effects of the passive damping devices is revisited, and, then a design methodology for the multi-modal case is defined. Also, it is briefly reviewed the optimization method used for design purposes, namely the LifeCycle Model. Finally, experimental results are reported, illustrating the success of using the methodology presented in passive damping applications applied to mechanical and mechatronic systems.

Scalable compact circuit model and synthesis for RF CMOS spiral inductors

Abstract: A scalable industry-oriented, 24-element "2-/spl pi/" compact circuit model for on-chip RF CMOS spiral inductors is presented. It has a good accuracy up to self-resonant frequency (SRF). Two levels of modeling approaches are provided, which are: 1) the fixed model, which extracts the values of circuit elements directly from the measured S-parameters of a given device, achieving high accuracy, but no scalability and 2) the scalable model, in which circuit elements are related to the geometry (i.e., layout) through a set of formulas with model parameters calibrated upon a few testing devices. The synthesis procedure is also discussed, which includes the scalable model and a SPICE simulator as the evaluation method within the iteration loop.

Design of Inductor Winding Capacitance Cancellation for EMI Suppression

Abstract: In this paper, the parasitics in both DM and CM inductors are first discussed. The methods for both DM and CM inductor winding capacitance cancellation are then proposed. Prototypes are designed and tested, using network analyzer. Finally, the prototypes are applied to practical power converters and EMI is measured. Both small signal measurement and practical EMI measurement prove that the proposed methods can efficiently reduce the effects of winding capacitance and therefore improve the inductor's filtering performance.

A Tunable RF MEMS Inductor on Silicon Incorporating an Amorphous Silicon Bimorph in a Low-Temperature Process

Abstract: A novel tunable radio frequency microelectromechanical system inductor based on the bimorph effect of an amorphous silicon (a-Si) and aluminum structural layer is presented. The outer turns of the inductor have a vertical height of 450 mum when no voltage is applied. A 32% tuning range with high inductance (5.6-8.2 nH) is achieved by the application of a voltage, with the structure completely flattening at 2 V. With no actuation, the peak quality factor is 15, and the self-resonance frequency is 7 GHz. The fact that the device is fabricated on Si in a low-temperature (150 degC) process enhances the potential for system integration