Showing papers on "Inductor published in 2002"

Current-sensing techniques for DC-DC converters

Abstract: Current sensing is one of the most important functions on a smart power chip. Conventional current-sensing methods insert a resistor in the path of the current to be sensed. This method incurs significant power losses, especially when the current to be sensed is high. Lossless current-sensing methods address this issue by sensing the current without dissipating the power that passive resistors do. Six available lossless current sensing techniques are reviewed. A new scheme for increasing the accuracy of current sensing when the discrete elements are not known is introduced. The new scheme measures the inductor value during the DC-DC controller startup.

Differentially driven symmetric microstrip inductors

Abstract: A differentially excited symmetric inductor that enhances inductor quality (Q) factor on silicon RFICs is presented. Compared with an equivalent single-ended configuration, experimental data demonstrate that the differential inductor offers a 50% greater Q factor and a broader range of operating frequencies. Predictions from full-wave simulations and a physics-based SPICE-compatible model are validated by experimental measurements on an inductor fabricated in a triple-level metal silicon technology. Application of the symmetric inductor to a cross-coupled oscillator improves output voltage swing and phase noise by 75% and 1.8 dB, respectively (for a given power consumption), while chip area is reduced by 35% compared to conventional inductor equivalents.

Coupled-inductor design optimization for fast-response low-voltage DC-DC converters

Abstract: Multiphase voltage regulator modules (VRMs) for microprocessor power delivery with coupled output inductors are discussed. Strong coupling is shown to be feasible and effective at reducing ripple if the correct magnetic topology is used. For more than two phases, this can be a "ladder" core with windings around each rung. Typical ripple reduction is better than a factor of six with no effect on response time. One can also chose to improve response time while still significantly reducing ripple. A simultaneous numerical optimization of the magnetics and the circuit is used to minimize loss in a fast-response 100 A design.

Frequency-independent equivalent circuit model for on-chip spiral inductors

Abstract: A wide-band, physical and scalable 2-/spl Pi/ equivalent circuit model for on-chip spiral inductors is developed. Using frequency-independent RLC elements, it accurately captures R(f) and L(f) characteristics beyond the self-resonant frequency. This new model is fully compatible with both AC and transient analysis. Verification with measurement data demonstrates excellent scalability for a wide range of inductor configurations.

High-frequency chip packages

Abstract: A packaged semiconductor chip includes features such as a chip carrier having a large thermal conductor which can be solder-bonded to a circuit board so as to provide enhanced thermal conductivity to the circuit board and electromagnetic shielding and a conductive enclosure which partially or completely surrounds the packaged chip to provide additional heat dissipation and shielding. The packaged unit may include both an active semiconductor chip and a passive element, desirably in the form of a chip, which includes resistors and capacitors. Inductors may be provided in whole or in part on the chip carrier. A module includes two circuits and an enclosure with a medial wall between the circuits to provide electromagnetic shielding between the circuits.

Tunable dual band antenna system

Abstract: A tunable dual band antenna system is disclosed. The system icludes a transceiver, a matching network and an antenna. The matching network is operable to tune the antenna to the transceiver at both a first and second frequency. Accordingly, the matching network has a variable capacitor, an inductor and a second capacitor. The value of the variable capacitor is chosen to tune the antenna at the first frequency and the second such that the system can be used to transmit and receive electromagnetic energy over two bandwidths. The values of the variable capacitor, the inductor, and the second capacitor are chosen to minimize the standing wave ratio of the system at both the first frequency and the second frequency.

Substrate effects in monolithic RF transformers on silicon

Abstract: The effect of substrate RF losses on the characteristics of silicon-based integrated transformers is studied experimentally by using a substrate transfer technique. The maximum available gain is used to evaluate the quality of transformers similarly to that of active devices. The silicon substrate has a pronounced effect on the quality factor and mutual resistive coupling factor of the primary and secondary coils, thereby degrading the maximum available gain of the transformer. A highly structured patterned ground shield is shown to improve the maximum available gain of a transformer at high frequencies, while at low frequencies, it has little effect on the maximum available gain and even degrades the quality factors of the transformer coils. It is shown that the low-frequency degradation of the coil quality factors relates to local eddy currents in the patterned metal shield.

Fast charger for high capacity batteries

Abstract: A highly efficient fast charger for high capacity batteries and methods for fast charging high capacity batteries. The fast charger preferably comprises a rectified AC input of single or preferably three phases, with an optional power factor corrected input, minimally filtered with high frequency, high ripple current capacitors, which is switched with a power switching circuit in the “buck” configuration into an inductor/capacitor output filter. Metallized film capacitors are employed, to minimize the rectified 360 Hertz AC component filtering while providing transient switch protection and ripple current requirements for the buck regulator, to provide a high current fast charger with substantially improved power factor. High power, high frequency switching with minimized output filter size provides a highly filtered DC output. The fast charger is adapted to be constructed in a modular design for simple maintenance.

Integrated magnetic for LLC resonant converter

Abstract: A new LLC resonant converter is proposed for front end DC/DC conversion in a distributed power system. This converter shows some potential benefits in this application. This paper proposes several integrated magnetic designs for LLC resonant converter. This converter has three magnetic components. With magnetic integration, first, a number of components can be reduced; secondly, flux ripple cancellation is achieved so that core loss is reduced. From these benefits, higher power density can be achieved. In design of the integrated magnetic structure for LLC resonant converter, a general model of four winding integrated magnetic structure is derived which can be used to derive integrated magnetic structure for different topologies. Finally, the test result is shown.

Synthetic ripple regulator

Abstract: A synthetic ripple regulator for a DC-DC converter generates an auxiliary voltage waveform that effectively replicates the waveform ripple current through an output inductor, and uses the auxiliary voltage waveform to control toggling of a hysteretic comparator. In a non-limiting implementation, a transconductance amplifier monitors the voltage across the inductor, and supplies an inductor voltage-representative current to a ripple waveform capacitor, so as to produce the auxiliary voltage waveform. Using the replicated inductor current for ripple regulation results in low output ripple, input voltage feed forward, and simplified compensation.

Comparison of various methods for calculating the AC resistance of inductors

Abstract: The paper reviews several expressions for high-frequency winding resistance of inductors proposed by several authors and compares the theoretical predictions calculated from these expressions with experimental results. It identifies the expressions that yield the most accurate prediction of the winding high-frequency resistance. The comparison shows that the method proposed by Dowell (1966) accurately predicts the AC resistance if the winding contains less than three layers. The methods proposed by several other authors accurately predict the high-frequency resistance only in certain frequency ranges. In addition, these expressions yield inaccurate results for the inductor quality factor. One expression, however, accurately predicts both the high-frequency winding resistance and the quality factor of inductors over a wide frequency range from the DC to the first resonant frequency. The paper concludes with a simple and accurate circuit model describing the frequency behavior of inductors.

Miniature 3-D inductors in standard CMOS process

Abstract: The structure of a miniature three-dimensional (3-D) inductor is presented in this paper. The proposed miniature 3-D inductors have been fabricated in a standard digital 0.35-/spl mu/m one-poly-four-metal (1P4M) CMOS process. According to the measurement results, the self-resonance frequency f/sub SR/ of the proposed miniature 3-D inductor is 34% higher than the conventional stacked inductor. Moreover, the inductor occupies only 16% of the area of the conventional planar spiral inductor with the same inductance and maximum quality factor Q/sub max/. A 2.4-GHz CMOS low-noise amplifier (LNA), which utilized the proposed miniature 3-D inductors, has also been fabricated. By virtue of the small area of the inductor, the size and cost of the radio frequency (RF) chip can be significantly reduced.

UPS inverter design using discrete-time sliding-mode control scheme

Abstract: This paper presents a novel discrete-time sliding-mode control algorithm for an uninterruptible power supply (UPS) inverter design. The approach offers a dual-loop design, in which a current predictor utilizes the tracking error of output voltage to estimate the desired inductor current, while a current controller is adopted to regulate the inductor current and, thus, produces a control command to the pulsewidth modulation inverter. An explicit condition for stable controller design is derived. The efficacy of this scheme is validated via a successful implementation on a digital-signal-processor-based UPS inverter. The proposed scheme has shown its robustness on low output voltage distortion, excellent voltage regulation, and it is insensitive to load variation, even under nonlinear loads. Experimental studies were performed to further validate the effectiveness of this scheme.

Comparison of low-frequency piezoelectric switching shunt techniques for structural damping

Abstract: In this paper, the performances of two novel low-frequency piezoelectric switching shunt techniques for structural damping are compared to the traditional passive tuned resonant shunt circuit technique. The first novel technique, state switching, is a semi-active variable stiffness technique in which bonded piezoelectric elements are switched from the short circuit to open circuit states. This technique changes the stiffness of the structure for two quarters of its vibration period, thus dissipating energy. The second novel technique, pulse switching, is a semi-active continuous switching technique in which a resistor/inductor shunt circuit is periodically connected to the bonded piezoelectric elements. This technique applies charges to the piezoelectric elements in a manner similar to the direct velocity feedback and bang-bang time optimal control techniques. A brief description of each of the damping techniques is given. Numerical simulations of the switching techniques are shown and compared to the resonant shunt damping technique. Finally, preliminary experimental results are presented for the resonant shunt, state switching, and pulse switching techniques on a simply supported beam.

Adjustable minimum peak inductor current level for burst mode in current-mode DC-DC regulators

Abstract: Switching regulator circuits and methods are provided for regulating output voltage that include an adjustable minimum peak inductor current level for Burst Mode in current-mode DC-DC regulators. Minimum peak inductor current level control is achieved during Burst Mode by allowing external control for adjusting the burst threshold level. A single pin can be used to distinguish between forced continuous and Burst Mode as well as set the burst threshold level during Burst Mode, or an alternate method of setting a variable burst threshold level can be implemented in which two pins are used, one for selecting the mode of operation and the other for setting the burst threshold level during Burst Mode. The above principles can be applied to both step-up and step-down regulator circuit configurations, as well as both synchronous switching regulators and non-synchronous switching regulators.

Wireless, passive, resonant-circuit, inductively coupled, inductive strain sensor

Abstract: This paper presents a non-contact, wireless, passive, inductively coupled strain sensor. The sensor itself is a parallel-connected LC tank circuit. Small geometric changes in a stressed solenoidal inductor were predicted to affect its inductance and as a consequence the resonant frequency of the LC circuit. Using a gate dip meter as a sensitive detector, this was experimentally confirmed. There was found to be a consistent relationship between relative strain with shifted resonant frequency independent of whether the sensor was embedded or not.

A Control Method to Damp Oscillation in the Input LC Filter of AC-DC PWM Converters

Abstract: A control method to damp oscillation in the input LC filter of AC-DC PWM converters is proposed in this paper. The oscillation in the input LC filter of AC-DC PWM converters is damped by using a virtual resistor that can be connected either in series to or parallel with filter inductor or capacitor. Because no real resistor is used, the efficiency of the converters is not sacrificed. The required additional sensor and implementation of the virtual resistor in the control algorithm is strongly influenced on how the virtual resistor is connected to the LC filter. We need an additional current sensor if the virtual resistor is connected in series to the filter inductor or capacitor and an additional voltage sensor if connected in parallel. Simulated and experimental results are included to verify the proposed method.

A novel resonant gate driver for high frequency synchronous buck converters

Abstract: This paper introduces a new resonant gate driver for both the top and bottom switches of a synchronous buck converter. A coupled inductor is used to reduce the size as well as to transfer energy between the top and bottom gate driving. A possible semiconductor integration approach is proposed for this resonant gate driver based on a self-adaptive control method. Theoretical analysis, simulation and experimental results prove that the proposed driver can greatly reduce the gate driving loss and that it is well suited to high-frequency applications.

A 0.5-8.5 GHz fully differential CMOS distributed amplifier

Abstract: A fully integrated fully differential distributed amplifier with 5.5 dB pass-band gain and 8.5 GHz unity-gain bandwidth is described. The fully differential CMOS circuit topology yields wider bandwidth than its single-ended counterpart, by eliminating the source degeneration effects of parasitic interconnect, bond wire, and package inductors. A simulated annealing CAD tool underpins the parasitic-aware methodology used to optimize the design including all on-chip active and passive device and off-chip package parasitics. Mixed-mode S-parameter measurement techniques used for fully differential circuit testing are reviewed. Integrated in 1.3/spl times/2.2 mm/sup 2/ in a standard 0.6 /spl mu/m CMOS process, the distributed amplifier dissipates 216 mW from a single 3 V supply.

Novel zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converter using coupled output inductor

Abstract: A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width-modulated (PWM) converter is proposed to improve the previously proposed ZVZCS full-bridge PWM converters. By employing a simple auxiliary circuit with neither lossy components nor active switches, soft-switching of the primary switches is achieved. The proposed converter has many advantages such as simple auxiliary circuit, high efficiency, low voltage stress of the rectifier diode and self-adjustment of the circulating current, which make the proposed converter attractive for the high voltage and high power applications. The principles of operation and design considerations are presented and verified on the 4 kW experimental converter operating at 80 kHz.

A new soft switching technique for buck, boost and buck-boost converters

Abstract: A new soft switching technique for buck, boost and buck-boost converters using a coupled inductor is proposed in this paper. The principles of operation of these converters are analyzed in detail. An additional winding is added on the same core of the main inductor for the purpose of commutation. By using hysteresis current control, zero voltage switching (ZVS) conditions are ensured over wide load range. The main inductor current is kept in continuous conduction mode (CCM) with small ripple, which allows high output power and small filter parameters. Also, the switching frequency is kept constant when load changes. Prototypes of buck, boost, and buck-boost converters have been built to verify the proposed concept. The experimental results are presented and they verify the analysis.

Micromachined high-Q inductors in a 0.18-/spl mu/m copper interconnect low-k dielectric CMOS process

Abstract: On-chip spiral micromachined inductors fabricated in a 0.18-/spl mu/m digital CMOS process with 6-level copper interconnect and low-K dielectric are described. A post-CMOS maskless micromachining process compatible with the CMOS materials and design rules has been developed to create inductors suspended above the substrate with the inter-turn dielectric removed. Such inductors have higher quality factors as substrate losses are eliminated by silicon removal and increased self-resonant frequency due to reduction of inter-turn and substrate parasitic capacitances. Quality factors up to 12 were obtained for a 3.2-nH micromachined inductor at 7.5 GHz. Improvements of up to 180% in maximum quality factor, along with 40%-70% increase in self-resonant frequency were seen over conventional inductors. The effects of micromachining on inductor performance was modeled using a physics-based model with predictive capability. The model was verified by measurements at various stages of the post-CMOS processing. Micromachined inductor quality factor is limited by series resistance up to a predicted metal thickness of between 6-10 /spl mu/m.

Improved quality-factor of 0.18-/spl mu/m CMOS active inductor by a feedback resistance design

Abstract: A novel CMOS active inductor approach, which can improve the quality-factor, was presented in this report. A cascode-grounded active inductor circuit topology with a feedback resistance was proposed, which can substantially improve its equivalent inductance and quality-factor. This feedback resistance active inductor was implemented by using a 0.18-/spl mu/m 1P6M CMOS technology, which demonstrates a maximum quality-factor of 70 with a 5.7-nH inductance at 1.55 GHz, where the self-resonant frequency is 2.5 GHz. The dc power consumption of this active inductor is less than 8 mW.

Design of 48 V Voltage regulator modules with a novel integrated magnetics

Abstract: The push-pull forward topology with the current-doubler and synchronous rectifier is a suitable approach for high-input voltage regulator modules (VRMs) used to supply high-performance microprocessors. In order to improve efficiency and reduce size, this paper proposes an improved push-pull forward converter with a novel integrated magnetics. All the magnetic components including input filter inductor, step-down transformer and output filter inductors are integrated into a single EI or EE core. This topology is essentially the modified push-pull converter with the built-in input filter and the coupled-inductor current doubler rectifier. The proposed integrated magnetic structure features a simple core structure, a small leakage inductance and low winding and core losses. A design is given for a 48-V VRM with a 1.2-V and 70-A output, and its experimental results show that the proposed approach can offer a great improvement in efficiency.

High voltage battery charger

Abstract: A simple and flexible battery charger for charging high voltage battery strings includes a DC-to-AC converter that drives the primary of a transformer having multiple secondaries Each secondary winding has a corresponding output stage formed of a rectification circuit, output inductor, and output capacitor The output terminals of the output stages are connectable either in parallel or series In either configuration, inductor current and capacitor voltage automatically balance among the output stage circuits A controller normally regulates output terminal voltage by operating in voltage mode, but limits current by operating in a current mode when the average of inductor currents exceeds a specified limit Reconfiguration from parallel to series, or vice versa, is obtained physical reconnection of the output stage terminals and adjustment of a single voltage feedback scaling factor Connecting the output stages in series to produce a high voltage output reduces voltage stresses on the rectification circuits and enables use of Schottky diodes to avoid reverse recovery problems

Multiphase clamp coupled-buck converter and magnetic integration

Abstract: Voltage regulation, transient response and efficiency of a voltage regulator module (VRM) is improved where short duty cycles are necessitated by large differentials of input and output voltage by including at least one clamping of a tap of an inductance in series with an output of each of a plurality of parallel branches or phases which are switched in a complementary fashion or providing coupling between inductors of respective phases. Such coupling between inductors is achieved in a small module with an integrated magnetic structure. Reduced component counts are achieved while deriving built-in input and output filters. Principals of the invention can be extended to isolation applications and push-pull forward converts, in particular. A lossless clamping circuit is also provided allowing spike currents to be suppressed while returning power to the output of the VRM.

Analysis and design of a new voltage sag compensator for critical loads in electrical power distribution systems

Abstract: In this paper, a new voltage sag compensator for powering critical loads in electric distribution systems is discussed. The proposed scheme employs a pulsewidth-modulation AC-AC converter (four insulated gate bipolar transistors per phase) along with an autotransformer. During a disturbance such as voltage sag, the proposed scheme supplies the missing voltage and helps in maintaining rated voltage at the terminals of the critical load. The approach does not employ any energy storage components such as bulk capacitors/inductors and provides fast response at low cost. Under normal conditions the approach works in bypass mode, delivering utility power directly to the load; this method of control allows the transformer to be rated only for transient conditions, thus reducing its required size. A four-step switching technique to drive the AC-AC converter is employed to realize snubberless operation. A design example is presented, and simulation results are shown for a three-phase 230-V 5-kVA system. Experimental results on a single-phase unit are discussed. The proposed approach can be easily integrated into a distribution transformer supplying critical loads.

Flashlamp drive circuit

Abstract: The invention provides a power supply or drive circuit for a pulsed flashlamp which utilizes a two-core component having common windings as both an inductor for arc mode drive and for breakdown triggering of the lamp. Discharge of a capacitor through the inductor and lamp is controlled by a high-speed semiconductor switch which is turned on and off by a suitable control, current flowing from the inductor through a one-way path including the lamp when the switch is off. The control maintains the ratio of the power variation through the lamp to the average power through the lamp substantially constant. The controls may also be utilized to control output pulse shape. Novel protective features are also provided for circuit components during turn on periods for the switch.

Integrated circuit inductors

Abstract: The invention relates to an inductor comprising a plurality of interconnected conductive segments interwoven with a substrate. The inductance of the inductor is increased through the use of coatings and films of ferromagnetic materials such as magnetic metals, alloys, and oxides. The inductor is compatible with integrated circuit manufacturing techniques and eliminates the need in many systems and circuits for large off chip inductors. A sense and measurement coil, which is fabricated on the same substrate as the inductor, provides the capability to measure the magnetic field or flux produced by the inductor. This on chip measurement capability supplies information that permits circuit engineers to design and fabricate on chip inductors to very tight tolerances.

A megahertz switching DC/DC converter using FeBN thin film inductor

Abstract: A dual spiral sandwiched thin film inductor with a dimension of 5 mm /spl times/ 5 mm was fabricated by a LIGA-like micromachined process. FeBN magnetic films were used as a core material. The inductance and quality factor value of the inductor were measured approximately 1 /spl mu/H and 4 up to 5 MHz, respectively. Using the FeBN film inductor, a hybrid dc/dc converter (15 mm /spl times/ 12 mm /spl times/ 1.5 mm) was designed and fabricated. The circuit topology of the converter was a zero voltage switching clamp voltage (ZVS-CV) buck converter. An input of 3.6 V was bucked to 2.7 V at a switching frequency of 1.8 MHz. The maximum power was 1.5 W. The measured efficiency of the buck converter reached a maximum value of 80% and kept stable up to 300 mA of load currents at 1.8 MHz.