Showing papers on "Decoupling (electronics) published in 2008"

A Decoupling Technique for Increasing the Port Isolation Between Two Strongly Coupled Antennas

Abstract: A compact decoupling network for enhancing the port isolation between two closely spaced antennas is proposed in this paper. In the network, we first connect two transmission lines (TLs) individually to the input ports of two strongly coupled antennas. The length of the TLs is designed so that the trans-admittance between ports changes from a complex one at the antenna inputs to a pure imaginary one. A shunt reactive component is then attached in between the TL ends to cancel the resultant imaginary trans-admittance. Finally, a simple lumped-element circuit is added to each port for input impedance matching. The even-odd mode analysis is adopted to investigate the currents excited on the antennas for predicting the radiation pattern of the two-element antenna array. Two examples of printed antennas at 2.45 GHz are tackled by using the proposed decoupling structure. The measurement results agree quite well with the simulation ones. High antenna isolation and good input return loss are simultaneously achieved in both cases, which demonstrates the feasibility of the structure. The decoupled antenna array in each example radiates, as prediction, toward different but complementary directions when the input power is fed in turn to the two input ports. The array efficiency is estimated better than 75% in each example. This pattern diversity effect is helpful for reducing the channel correlation in a multiple-input multiple-output (MIMO) communication system.

An Eigen-Analysis of Compact Antenna Arrays and Its Application to Port Decoupling

Abstract: Placing the radiators of antenna arrays closer than aggravates the problem of power mismatch. Based on efficiency considerations, a general analysis of this effect is presented, putting forward a simple tool to quantify, compare, and optimize the performance of antenna arrays. This analysis is not restricted with respect to the number of radiators or the degree of compactness. In order to improve power matching, a systematic approach for the design of lossless decoupling and matching networks based on 180 directional couplers is suggested for up to eight radiators. Implications of network losses, which have not yet received appropriate attention by researchers in the past, will be analyzed and discussed by means of a manufactured three-element prototype array.

Vector Control of Three-Phase AC Machines: System Development in the Practice

Abstract: Principles of vector orientation and vector orientated control structures for systems using three-phase AC machines.- Inverter control with space vector modulation.- Machine models as a prerequisite to design the controllers and observers.- Problems of actual-value measurement and vector orientation.- Dynamic current feedback control for fast torque impression in drive systems.- Equivalent circuits and methods to determine the system parameters.- On-line adaptation of the rotor time constant for IM drives.- Optimal control of state variables and set points for IM drives.- Nonlinear control structures with direct decoupling for three-phase AC drive systems.- Linear control structure for wind power plants with DFIM.- Nonlinear control structure with direct decoupling for wind power plants with DFIM.- Appendices.

Port Decoupling for Small Arrays by Means of an Eigenmode Feed Network

Abstract: An alternative approach to port decoupling and matching of arrays with tightly coupled elements is proposed. The method is based on the inherent decoupling effect obtained by feeding the orthogonal eigenmodes of the array. For this purpose, a modal feed network is connected to the array. The decoupled external ports of the feed network may then be matched independently by using conventional matching circuits. Such a system may be used in digital beam forming applications with good signal-to-noise performance. The theory is applicable to arrays with an arbitrary number of elements, but implementation is only practical for smaller arrays. The principle is illustrated by means of two examples.

Port Decoupling for Small Arrays by Means of an

Abstract: An alternative approach to port decoupling and matching of arrays with tightly coupled elements is proposed. The method is based on the inherent decoupling effect obtained by feeding the orthogonal eigenmodes of the array. For this purpose, a modal feed network is connected to the array. The decoupled external ports of the feed network may then be matched inde- pendently by using conventional matching circuits. Such a system may be used in digital beam forming applications with good signal-to-noise performance. The theory is applicable to arrays with an arbitrary number of elements, but implementation is only practical for smaller arrays. The principle is illustrated by means of two examples.

Debt, Equity and Hybrid Decoupling: Governance and Systemic Risk Implications

Abstract: We extend here our prior work, which focused on equity decoupling ( Hu and Black, 2006, 2007, 2008), by providing a systematic treatment of debt decoupling and an initial exploration of hybrid decoupling. Equity decoupling involves unbundling of economic, voting, and sometimes other rights customarily associated with shares, often in ways that may permit avoidance of disclosure and other obligations. We discuss a new U.S. court decision which will likely curtail the use of equity decoupling strategies to avoid large shareholder disclosure rules. Debt decoupling involving the unbundling of the economic rights, contractual control rights, and legal and other rights normally associated with debt, through credit derivatives and securitisation. Corporations can have empty and hidden creditors, just as they can have empty and hidden shareholders. ‘Hybrid decoupling’ across standard equity and debt categories is also possible. All forms of decoupling appear to be increasingly common. Debt decoupling can pose risks at the firm level for what can be termed ‘debt governance’ − the overall relationship between creditor and debtor, including creditors’ exercise of contractual and legal rights with respect to firms and other borrowers. Widespread debt decoupling can also involve externalities and therefore create systemic financial risks; we explore those risks.

Fast Dynamic Control of Medium Voltage Drives Operating at Very Low Switching Frequency—An Overview

Abstract: Medium voltage AC machines fed by high-power inverters operate at a low switching frequency to restrain the switching losses of power semiconductor devices. Particular care is thus required in the design of the drive control system. The signal delay caused by low switching frequency operation increases undesired cross-coupling effects in vector-controlled schemes. These are not sufficiently compensated by established methods like feedforward control. Improvements are achieved by a more accurate modeling of the machine and the inverter. An adequate controller is introduced, having a transfer function with complex coefficients. The high harmonic distortion due to the low switching frequency is a tradeoff. Using synchronous optimal pulsewidth as an alternative permits reducing the switching frequency without increasing the harmonics. The detrimental effects of conventional control methods are eliminated by forcing the harmonic components on an optimal spatial trajectory. Deadbeat behavior and complete decoupling are thus achieved. The performance of the aforementioned schemes is compared based on mathematical analyses and experimental results.

Effective Radii of On-Chip Decoupling Capacitors

Abstract: Decoupling capacitors are widely used to reduce power supply noise. On-chip decoupling capacitors have traditionally been allocated into the white space available on a die or placed inside the rows in standard cell circuit blocks. The efficacy of on-chip decoupling capacitors depends upon the impedance of the power/ground lines connecting the capacitors to the current loads and power supplies. A design methodology for placing on-chip decoupling capacitors is presented in this paper. A maximum effective radius is shown to exist for each on-chip decoupling capacitor. Beyond this effective distance, a decoupling capacitor is ineffective. Depending upon the parasitic impedance of the power distribution system, the maximum voltage drop seen at the current load is caused either by the first droop (determined by the rise time) or by the second droop (determined by the transition time). Two criteria to estimate the minimum required on-chip decoupling capacitance are developed based on the critical parasitic impedance. In order to provide the required charge drawn by the load, the decoupling capacitor has to be charged before the next switching cycle. For an on-chip decoupling capacitor to be effective, both effective radii criteria should be simultaneously satisfied.

Decoupled Current Control of Sensorless Induction-Motor Drives by Integral Sliding Mode

Abstract: This paper discusses the problems of current decoupling control and controller tuning associated with sensorless vector-controlled induction-motor (IM) drives. In field-oriented control, the d-q synchronous-frame currents should be regulated to have independent dynamics such that the torque production of the IM resembles that of a separately excited dc motor. However, these currents are not naturally decoupled, and decoupling compensators should be used. Current loop tuning is an additional problem, since controller gains obtained by theoretical methods or simulation, quite often, do not work well on the real system. This paper proposes a new approach for current control that uses integral-sliding-mode (ISM) controllers to achieve decoupling. The synchronous-frame control voltages are synthesized as the sum of two controller outputs: a traditional one (PI) that acts on an ideal plant model and an ISM controller. The ISM controller decouples the d-q currents and compensates the parameter variations in the current loops of the machine. Simulations and experimental tests on a 0.25-hp three-phase induction machine show satisfactory results.

Erratum to "Implementation Issues and Performance Evaluation of Sinusoidal, Surface-Mounted PM Machine Drives With Hall-Effect Position Sensors and a Vector-Tracking Observer"

Abstract: This paper presents the implementation of the Hall-effect sensor-based, vector-tracking observer and discusses its performance when used in an ac brushless drive for surface-mounted PM machines. First, the tuning of the observer is presented. Then, decoupling is used to improve the performance of the observer. Various decoupling strategies are investigated. Stability analysis is also carried out that leads to a maximum amount of position estimation error for the observer to track properly. This paper also demonstrates the benefits of harmonic decoupling with respect to position estimation and disturbance rejection. Both simulation and experimental testing are used to illustrate the performance and limits of the proposed observer topology and of the drive when this observer is used for state feedback.

Nonlinear Control and Disturbance Decoupling of HVAC Systems Using Feedback Linearization and Backstepping With Load Estimation

Abstract: A new control methodology is introduced for nonlinear and MIMO heating, ventilating and air conditioning (HVAC) systems. A full information feedback of states and disturbances is used for disturbance decoupling and model linearization purposes. Then a backstepping controller is applied to the system linearized model. It is shown that in this way, heat and moisture loads can be compensated completely if considered as measurable disturbances. For non-measurable disturbances, a stable observer is designed for estimation purpose. Simulation results show that the closed-loop system has good and fast tracking, offset-free and smooth response with high disturbance decoupling and optimal energy consuming properties in presence of time-varying loads.

Techniques for providing decoupling capacitance

Abstract: Techniques for electronic device fabrication are provided. In one aspect, an electronic device is provided. The electronic device comprises at least one interposer structure having one or more vias and a plurality of decoupling capacitors integrated therein, the at least one interposer structure being configured to allow for one or more of the plurality of decoupling capacitors to be selectively deactivated. In another aspect, a method of fabricating an electronic device comprising at least one interposer structure having one or more vias and a plurality of decoupling capacitors integrated therein comprises the following step. One or more of the plurality of decoupling capacitors are selectively deactivated.

Broadband Decoupling and Matching of a Superdirective Two-Port Antenna Array

Abstract: Decoupling and matching networks may be used to improve the performance of compact antenna arrays where mutual radiator coupling has caused a degradation of the diversity capabilities. A popular network consists of a 180deg rat-race directional coupler, which decouples the antenna ports, followed by impedance matching networks at each port. Researchers, however, usually neglect the presence of losses both within the antenna array and the decoupling and matching network. For this reason, we have built various narrowband and broadband matching networks and compare their performances with the help of calibrated far-field measurement data.

Decoupling scanning from handoff for reduced delay over wireless lan

Abstract: Methods and systems for handing off a wireless client between access points wherein the scanning for access points in decoupled from the handing off, thus reducing the delay in the handing off.

Acoustic transducer assembly

Abstract: An acoustic transducer assembly comprises a bipolar transducer (1 ) having an active surface with opposite ends that move towards and away from one another in response to an applied electrical fields An acoustic decoupling material (2) is fixed to one end of the transducer surface, the acoustic decoupling material being such that it substantially prevents acoustic signals passing therethrough and substantially prevents coupling of the transducer's active surface

Layout of Decoupling Capacitors in IP Blocks for 90-nm CMOS

Abstract: On-chip decoupling capacitors (decaps) in the form of MOS transistors are widely used to reduce power supply noise. This paper provides guidelines for standard cell layouts of decaps for use within Intellectual Property (IP) blocks in application-specific integrated circuit (ASIC) designs. At 90-nm CMOS technology and below, a tradeoff exists between high-frequency effects and electrostatic discharge (ESD) reliability when designing the layout of such decaps. In this paper, the high-frequency effects are modeled using simple equations. A metric is developed to determine the optimal number of fingers based on the frequency response. Then, a cross-coupled design is described that has been recently introduced by cell library developers to handle ESD problems. Unfortunately, it suffers from poor response times due the large resistance inherent in its design. Improved cross-coupled designs are presented that properly balance issues of frequency response with ESD performance, while greatly reducing thin-oxide gate leakage.

Two nearby dual-band antennas with high port isolation

Abstract: The structure of two dual-band nearby antennas with high port isolation is proposed. The decoupling and matching network consist of only reactive elements so that it does not dissipate the input power. For dual-band antenna, it is usually easier to have high isolation in high frequency band (5 GHz) due to its short wave length. Therefore, the decoupling design can be turned to improve low frequency band and not to influence the high frequency band as much as possible. Besides, the matching circuit is still required to match both low and high bands for maintaining good impedance matching. Measurement results demonstrate the good performance of the proposed configuration.

Modeling and Adaptive Decoupling of Transient Resistance and Temperature Effects in Carrier-Based Sensorless Control of PM Synchronous Machines

Abstract: This paper analyzes the effects of the transient resistances in saliency tracking-based sensorless control methods of PM synchronous machines. A high frequency model of the PM synchronous machine including both stator and rotor transient resistance is presented. From this model, potential sources of error in the estimated position due to the transient resistances are analyzed, and their compensation by means of an adaptive decoupling mechanism is proposed. The paper also addresses the influence and compensation of temperature effects in carrier signal injection-based sensorless techniques.

Stability and Almost Disturbance Decoupling Analysis of Nonlinear System Subject to Feedback Linearization and Feedforward Neural Network Controller

Abstract: This paper studies the tracking and almost disturbance decoupling problem of nonlinear system based on the feedback linearization and multilayered feedforward neural network approach. The feedback linearization and neural network controller guarantees exponentially global uniform ultimate bounded stability and the almost disturbance decoupling performance without using any learning or adaptive algorithms. The proposed approach provides the architecture of the neural network and the weights among the layers in order to guarantee stability of the system. Moreover, the new approach renders the system to be stable with the almost disturbance decoupling property at each step of selecting weights to enhance the performance if the proposed sufficient conditions are maintained. This study constructs a controller, under appropriate conditions, such that the resulting closed-loop system is valid for any initial condition and bounded tracking signal with the following characteristics: input-to-state stability with respect to disturbance inputs and almost disturbance decoupling performance. One example, which cannot be solved by the first paper on the almost disturbance decoupling problem, is proposed in this study to exploit the fact that the tracking and the almost disturbance decoupling performances are easily achieved by our proposed approach. In order to demonstrate the practical applicability, a famous ball-and-beam system has been investigated.

Elimination of “Harmonic Transfer Through Converters” in VSC-Based Multiterminal DC Systems by AC/DC Decoupling

Abstract: ldquoHarmonic transfer through convertersrdquo has caused waveform distortion in multiterminal dc systems based on a voltage-source converter (VSC-MTDC). The harmonic transfer can be by the positive and negative sequences or by the zero sequence. A comprehensive solution consists of decoupling the ac side from the dc side of the VSC. Such decoupling has other benefits in VSC-MTDC because disturbances on the ac side of any VSC do not propagate to other VSCs (except the VSC assigned to function as the dc Voltage Regulator). Decoupling also allows a VSC to be planned and designed independently of the other VSCs of the MTDC.

Semiconductor device with decoupling capacitor design

Abstract: An integrated circuit includes a circuit module having a plurality of active components coupled between a pair of supply nodes, and a capacitive decoupling module coupled to the circuit module. The capacitive decoupling module includes a plurality of metal-insulator-metal (MiM) capacitors coupled in series between the pair of supply nodes, wherein a voltage between the supply nodes is divided across the plurality of MiM capacitors, thereby reducing voltage stress on the capacitors.

Buried emitter solar cell structures: Decoupling of metallisation geometry and carrier collection geometry of back contacted solar cells

Abstract: We present a novel solar cell structure, the “buried emitter solar cell”. This concept is designed for decoupling the metallisation geometry from the geometry of the carrier collecting p–n junction in back-contacted (and in particular back-junction) solar cells without requiring electrical insulation by dielectric layers. The most prominent features of this device structure are a carrier collecting emitter that covers close to 100% of the total cell area and an effective electrical insulation between emitter and base metallisation via a p+–n+ junction. The experimental results presented in this paper report a 19.5% efficient “buried emitter solar cell”, where 50% of the solar cell's rear side exhibit a p+–n+ junction. This preparation technique implies covering a boron-doped p-type emitter with an n-type surface layer that can be efficiently surface-passivated by thermal oxidation. All structuring of this cell has been performed by laser processing without any photo-lithography. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Magnetic Coupling Device

Abstract: A hand-actuated magnetic coupling or closing device, consisting of elements that are integrally connected either to the objects that are to be coupled or applied to the objects The coupling device comprises the following characteristics: Elements are coupled together by means of a coupling element; the coupling element can be displaced in two degrees of freedom; in the first degree of freedom, the coupling element can be displaced about the play between a coupling position and a decoupling position; in the second degree of freedom, the coupling element can be moved in a sliding manner by means of an input actuation A magnetic element is arranged and a magnetic system is arranged in the coupling element In the second degree of freedom and by means of the input actuation, the coupling element is displaced from the coupling position, in which the coupling element is attracted into the decoupling position, in which the coupling element is repelled and displaced about the play in the first degree of freedom