Abstract: In this paper, we investigate on the use of non-Foster active elements to increase the operation bandwidth of a split-ring resonator (SRR) for possible application in metamaterial-inspired components. First, we design the circuit topology of the active load required to compensate the intrinsic reactance of the SRR and get a broadband response. Then, we show that the same procedure can be successfully applied to the case of a SRR-based monopole antenna and, in principle, to any metamaterial-inspired device employing SRRs. Finally, integrating an electromagnetic and a circuit simulator, we propose a possible realistic implementation of the active load, based on the employment of commercially available circuit elements. The obtained results (seven times improvement of the impedance bandwidth of the SRR-based monopole antenna) prove that non-Foster active loads can be successfully used to overcome the inherent narrow-band operation of SRR-based passive metamaterials and metamaterial-inspired components. The implementation issues related to circuit element dispersion, parasitic effects, and stability of the active circuit are fully considered in the proposed design.

Abstract: In this letter, a new output combining network for the implementation of a Doherty Power Amplifier (DPA) is presented. The proposed topology simultaneously allows the active load modulation and the output matching, by adopting more realizable elements than the standard DPA, especially when high output power levels are required. The innovative design approach is demonstrated through a practical prototype realization based on GaN-HEMT devices. Experimental results have shown a 65%-48% efficiency at about 42-36 dBm output power with a gain compression lower than 1.5 dB from 1.95 to 2.25 GHz.

Abstract: Active load modulation antennas for contactless systems typically require the presence of a battery power source in the transponder device. The transponder typically cannot be powered by the reader device alone and also transmit an active load modulation signal. Embodiments in accordance with the invention are disclosed that allow transponder devices to transmit an active load modulation signal when powered only by the reader in the contactless system.

Abstract: The aeroelastic response of wind turbines is often simulated in the time domain using indicial response techniques. Unsteady aerodynamics in attached flow are usually based on Jones’s approximation of the flat plate indicial response, although the response for finite-thickness airfoils differs from the flat plate one. The indicial lift response of finite-thickness airfoils is simulated with a panel code, and an empirical relation is outlined connecting the airfoil indicial response to its geometric characteristics. The effects of different indicial approximations are evaluated on a 2D profile undergoing harmonic pitching motion in the attached flow region; the resulting lift forces are compared to CFD simulations. The relevance for aeroelastic simulations of a full wind turbine is also evaluated, and the effects are quantified in terms of variations of equivalent fatigue loads, ultimate loads, and stability limits. The agreement with CFD computations of a 2D profile in harmonic motion is improved by the indicial function accounting for the finite-thickness of the airfoil. Concerning the full wind turbine aeroelastic behavior, the differences between simulations based on Jones’s and finite-thickness indicial response functions are rather small; Jones’s flat-plate approximation results in only slightly larger fatigue and ultimate loads, and lower stability limits. Copyright c © 2012 John Wiley & Sons, Ltd.

Abstract: An active load pull waveform measurement system has been utilized to investigate, by drain current waveform analysis, the effect of short circuits at the second and higher harmonics on the gate of a 750 μm Gallium Arsenide transistor. It is confirmed that the half wave rectified sinusoidal current waveform necessary for modes of operation such as class B, J and F is not optimally generated at X-Band frequencies for transistors controlled purely by bias. The disrupting effect of the nonlinear device gate capacitance must be accounted for to take full advantage of these high efficiency modes. The addition of a simple wide band filter circuit at the input of a MMIC test cell to “short” the gate higher harmonics is shown to force the drain current waveform towards the ideal case and hence yield a significant increase in drain efficiency of up to 10 percent.

Abstract: Economic dispatch (ED) is an optimisation tool that is used to allocate active load demands to the generating units through optimising the fuel generation cost function subject to the different operational constraints. The high non-linearity of the power system imposes mathematical challenges in formulating the generation cost function models, which makes the ED problem hard to solve. This study introduces two ideas to solve issues related to the ED problem. First, a dynamic formulation technique is developed to optimally allocate the change in the total active load demand to the generating units. This technique is shown to be insensitive to the optimality of the initial active load distribution unlike the base point and participation factor method. Moreover, it guarantees an optimal distribution among the generating units due the change in the active load demand. Second, a novel approximation of the non-convex generation cost function is developed to solve non-convex ED problem with the transmission losses. This approximation enables the use of gradient and Newton techniques to solve the non-convex ED problem with valve point loading effect and transmission losses in an analytic approach. This approximation is compared with some heuristic optimisation techniques.

Abstract: Various embodiments of methods and systems for managing battery load in a portable computing device ("PCD") are disclosed. One such method includes tracking an active load on a battery attributable to one or more active power consuming components. Measurements associated with the battery and indicative of the battery's state of health may also be monitored. When a call for additional load on the battery is recognized, such as a user request for provision of additional functionality in the PCD, a future load on the battery that considers the newly called load can be calculated. Based on an analysis of the impact on the battery's state of health, existing, lower priority loads may be scaled or suspended to create battery load capacity for the newly called load. In this way, quality of service and user experience may be optimized while minimizing conditions that could be detrimental to the battery.

Abstract: A power control device has a voltage-regulator from power source to load, the load configurable to receive power at least at a first or second rate. The device has monitor circuitry to measure power; signal circuitry for signaling a power-reception rate to the load; and circuitry for resetting the load when the power source is overloaded. The device resets the load periodically to the second rate when the load is at the first rate. In embodiments, the power source is a thermoelectric generator or solar panel. In embodiments, the load couples through a USB connector. A companion method of charging smart loads includes applying power to the load; communicating power available to the load; configuring a battery charger in the load to absorb an amount of power less than that available; monitoring power, determining when changed configuration may optimize charging time of a smart load battery; and resetting the smart load to optimize current.

Abstract: In this paper a novel active open-loop multi-band load-pull measurement system is presented. The system uses few components where the main parts are an Oscilloscope and an Arbitrary Waveform Generator (AWG). The used AWG is a sophisticated signal generator with two outputs, letting the user take full control over the injected signals in the frequency band 0-4 GHz. This enables new kinds of measurements to be performed, such as multi-band load-pull and in particular inter-modulation product load-pull, which this paper focuses on. The paper describes the measurement setup briefly and the calibration and load-pull algorithms used. As an example to demonstrate the capabilities of the system, a multi-band load-pull is carried out on a GaN HEMT transistor. The frequency bands are 2.14 GHz and 2.65 GHz which create IM3 products at 1.63 GHz and 3.16 GHz. It is shown that the efficiency is affected by the choice of load termination presented at the IM3 frequencies.

Abstract: There is described an RF bidirectional communication device utilizing active load modulation, the device comprising (a) a resonance circuit including an antenna (326), and (b) a control unit (322) for controlling communication of the device, including switching between a transmission mode and a receiving mode, wherein the control unit is adapted to (c) modify a configuration of the resonance circuit such that the resonance circuit has a first resonance frequency (f0) when the device is in the transmission mode and a second resonance frequency (f0+Δf) when the device is in the receiving mode, and (d) modify the configuration of the resonance circuit such that a Q-factor of the resonance circuit is periodically decreased while the device is in the transmission mode. There is also described a corresponding method and a system comprising a RF device and a reader/writer device. Furthermore, there is described a computer program and a computer program product.

Abstract: A fully on-chip linear regulator is presented in this paper to enhance the load transient response in a switch mode power supply (SMPS). Different from the conventional linear regulator, it employs a push-pull output structure, allowing both step-up and step-down transient current compensation. A multi-level self-biased controller is designed to adaptively compensate the instantaneous current difference between the SMPS and the load, achieving ultra-fast and smooth load transient response. An IC prototype is designed and fabricated with a standard 0.35μm digital CMOS process. 40.3ns load transient response time is achieved for a 100-mA load step change. In addition, it is also capable of dynamic voltage scaling (DVS), with a measured tracking speed of about 1 V/μs.

Abstract: The invention discloses a partition power grid bus load prediction system based on weather information Real-time weather information and prediction weather information are used in the system, load prediction of all buses of converting stations of 500 kV and 220 kV is achieved, and recognition of power grid partition and partition load prediction are achieved A prediction algorithm used by the system comprises a classical algorithm and an intelligent prediction algorithm, the classical algorithm comprises unary linear regression, quadratic polynomial regression, self-adaptation index prediction, index prediction, increasing rate prediction, nonhomogeneous index prediction, a B Compertz model and a logistic model, the intelligent prediction algorithm comprises an optimized BP neural network algorithm and an optimized particle swarm algorithm, and the system selects a prediction algorithm in a preferential mode during a prediction process The system is a day-ahead bus load prediction system, bus load and partition load of each time interval from morrow to multiple days in future are predicted, and prediction content is active load of 96 points of a predicted day

Abstract: Techniques for sensing the resistance of a load. In an aspect, a sense resistor is provided in series with the load. Each terminal of the sense resistor is alternately coupled via switches to a sense amplifier. A second input of the sense resistor is coupled to a terminal of the load. The voltage drop across the load and the voltage drop across the load plus sense resistor are alternatively measured. These voltage drops may be digitized and used to compute a resistance of the load using, e.g., a digital processor.

Abstract: PROBLEM TO BE SOLVED: To provide a load current protective circuit that suitably protects a load from overcurrent.SOLUTION: An overcurrent protective circuit 100 that protects a load 14 from overcurrent comprises: load current cut-off condition specifying sections 25, 27, and 29 that specify two or more load current cut-off conditions, which are conditions requiring that load current not lower than a specified current flows for a specified time or longer in order to cut off load current; detecting means 30 for detecting, in terms of one or more of the load current cut-off conditions, that a load current not lower than the specified current has flowed for the specified time or longer; and a load current cut-off section 131 that shuts off a load current if the detecting means detects that at least one of the load current cut-off conditions is satisfied.

Abstract: Three-phase four-wire distribution systems are widely used in many countries. These power distribution systems are used for both three-phase three-wire loads and single-phase two-wire consumer appliances in South Korea, Myanmar and other countries. Unbalanced load conditions always occur in three-phase four-wire distribution systems. These unbalanced load conditions cause unbalanced voltages for three-phase and single-phase loads, and increase the loss in the distribution transformer. In this paper, we propose an active load balancer (ALB) based on constant DC capacitor voltage control for three-phase four-wire distribution systems. Constant DC capacitor voltage control is always used in active power line conditioners. The proposed control algorithm does not require any computation blocks to calculate the active and reactive currents on the distribution system. Balanced source currents with a unity power factor are obtained without any calculation blocks of the unbalanced active and reactive components on the load sides. The basic principle of the constant DC capacitor voltage control based strategy for the ALB is discussed in detail and then confirmed by digital computer simulation using PSIM software. A prototype experimental model is also constructed and tested to validate the feasibility of the proposed control algorithm. Simulation and experimental results demonstrate that the proposed ALB can balance the source currents with a unity power factor for a three-phase four-wire distribution system.

Abstract: A charging circuit includes a first current mirror including a first branch circuit, a second branch circuit and a third branch circuit for generating a first conduction current, a second conduction current and a third conduction current according to the input voltage, a second current mirror including a fourth branch circuit coupled to the first branch circuit and including a first channel width, and a fifth branch circuit coupled to the second branch circuit and including a second channel width, wherein a load circuit is coupled between the first current mirror and the second current mirror, and the first current mirror as well as the second current mirror correspondingly adjust values of the first conduction current, the second conduction current and the third conduction current according to the first channel width as well as the second channel width, so as to process a charging operation of the load circuit.

Abstract: This study presents the development of an electronic system for load control of a single-phase permanent magnet synchronous generator which operates in stand-alone mode. Considering that the generator input power is kept constant, the control system goal is to ensure that the generator output power is also kept constant, even if changes in the user load consumption occur. A switched binary-weighted ballast load is connected in parallel to the user load. It is composed of six resistors connected in series. These resistors will absorb the power not used by the user. A power electronic switch is connected in parallel to each ballast load resistor. Each switch is triggered in integer cycles. The on/off combination of these switches provides 64 options of equivalent resistances that vary linearly.

Abstract: A diagnostic system configured to testing a performance of a vehicle component may include a processor configured to process test information from the vehicle component and control the vehicle component to be tested. The diagnostic system may also include a memory configured to store the test information of the vehicle component and software that operates the vehicle component. The diagnostic system may further include a monitoring module configured to monitor a power supply provided to perform the testing of the vehicle component and cuts off the power supply when the power exceeds a predetermined threshold.

Abstract: Based on the time process characteristic and economic efficiency characteristic of the civilian active load system's interaction demand response,a behavior analysis mode of active load's interaction response is proposed.A demand response operation-decision model is developed to maximize the profits of users and power industries,even with social welfare taken into account.Then an evaluation index system is proposed that can represent and identify the physical features of the interactive response behavior among users'energy demands,electricity demands and the cooperation between distributed renewable energy and grid by the decoupling response behaviors between users' energy consuming load and electric load.Finally,the effectiveness of the model and index system proposed is verified by an analysis of the residential and commercial quarters active load system's response behavior in the heavy space cold load grid,respectively,the active load system consisting of cold storage air conditioning and distributed wind generation in the heavy air-conditioning cold load grid.

Abstract: This paper presents the design of a single-ended input, differential output low noise amplifier for GPS applications in 0.18 µm CMOS technology. This Low Noise Amplifier (LNA) is composed of a common source (CS) amplifier adopted with a common gate, common source (CGCS) balun load. Instead of spiral on-chip inductor, a differential active inductor circuit (DAI) is used as an active load of balun and also gm-boosting technique is used to decrease the noise figure (NF) of Single-to-Differential Low Noise Amplifier (S-to-D LNA). The LNA is simulated with Cadence Spectra which shows the S21 of 22.94 dB at 1.57 GHz, S11 of −13.1 dB, NFmin of 2.66 dB and power dissipation of 2.5 mw from 1.8 V dc power supply. By adding an external capacitor to the DAI circuit, it is possible to reconfigure the LNA to use in multi frequency range. For using the LNA in frequency range of 1.22 GHz, the external capacitor is set to 121 fF. The result shows the S21 of 20.4 dB, S11 of −12.4 dB and NFmin of 2.4 dB.

Abstract: A method of operating a switched-mode power supply (SMPS) for supplying power to a load circuit, which draws a supply current that varies with an input signal to the load circuit is disclosed. The method comprises monitoring the input signal and controlling the amount of accumulated energy transferred for consumption by the load circuit, in use, in accordance with the input signal.

Abstract: A circuit protection device 122 for monitoring a current flowing from an electrical distribution line through a trip mechanism 132 to a load 124 includes an input conductor 210 configured to receive a current signal from a sensor. At least one resistor 204 is arranged to receive the current signal from the input conductor, and provides a voltage signal proportional to the current signal. The circuit protection device includes a control circuit 208 coupled in parallel with the resistor 204 and a power supply 206 that receives the current signal from the resistor 204 and supplies power to the control circuit based on the current signal. The control circuit 208 is configured to receive the voltage signal and determine an amplitude of the current flowing through the trip mechanism 132 based on the voltage signal. The control circuit 208 is also configured to determine whether a predetermined current threshold is exceeded and to generate a control signal to activate the trip mechanism 132.

Abstract: A switching regulator or other apparatus or techniques can include load current monitoring to provide a digital representation of an estimated load current. Load current monitoring can be performed by a circuit including a counter circuit, a comparator circuit, and a digitally-controlled source coupled to the counter circuit and configured to adjust a bias condition of a sensing device in response to a count provided by the counter circuit in order to establish a proportional relationship between a current conducted by the sensing device and a corresponding current conducted by a power switching device. The counter circuit is configured to increment and decrement the count in response to information provided by the comparator output and the count is generally indicative of the estimated load current, such as an average load current.

Abstract: With this work we address the linearity characterization of active devices within an active load pull characterization setup. Realistic real-life circuit scenarios can be mimicked and adjusted without compromise or tradeoffs in favor of improved EVM and ACPR for communication standard compliant test signals like LTE advanced.

Abstract: A current mirror circuit having formed in a semiconductor: a pair of transistors arranged to produce an output current through an output one of the transistors proportional to a reference current fed to an input one of the pair of transistors; a resistor comprising a pair of spaced electrodes in ohmic contact with the semiconductor, one of such pair of electrodes of the resistor being coupled to the input one of the pair of transistors; and circuitry for producing a voltage across the pair of electrodes of the resistor, such circuitry placing the resistor into saturation producing current through a region in the semiconductor between the pair of spaced ohmic contacts, such produced current being fed to the input one of the transistors as the reference current for the current mirror.

Abstract: Current mirror circuit has served as the basic building block in analog circuit design since the introduction of integrated circuits. In this paper, “A Very high impedance current mirror, operating in reduced power supply which does not use any additional biasing circuit and its application” is proposed. The design uses a high swing super Wilson current mirror which has negative feedback. A feedback action is used to force the input and output currents to be equal. The output current is expected to be mirrored with a transfer error less than 1% when the input current is increased from 5μA to 40μA. As an application, the current mirror circuit has been used in the design of a high gain, improved output swing differential amplifier. A telescopic differential amplifier is chosen for designing since it is used in low power application. A comparative study of different current mirror circuits and amplifier is also made. The output swing of the circuit is improved than what is expected.

Abstract: A current mirror circuit provides a current to drive a load. A noise cancelling circuit is provided to keep the load current constant in spite of variations in the supply voltage. The noise cancelling circuit includes an auxiliary current path which branches from the load current path. The length-to-width ratios of transistors of the circuit are selected to provide the desired noise cancellation while maintaining device stability.

Abstract: A bandgap reference voltage circuit comprises a current mirror unit, an operation amplifier (OP), a first resistor, a second resistor, an auxiliary unit, and a voltage generation circuit. An output end of the OP is coupled to a feedback end of the current mirror unit. An end of the first resistor and an end of the second resistor are coupled to a positive input end of the OP. Another end of the first resistor is coupled to a second end of the current mirror unit. A second end of the voltage generation circuit is coupled to another end of the second resistor. An end of the auxiliary unit is coupled to a negative input end of the OP and a first end of the voltage generation circuit, and another end of the auxiliary unit is coupled to the first end of the current mirror unit.

Abstract: In this paper, a new electronically tunable active resistance was introduced. The proposed circuit design consists of only two differential amplifiers. The main advantages of this circuit are higher bandwidth, simpler design and tunable resistance range. Also, the design of the circuit allows negative resistance structure and besides it can be used in IC realizations. Effective range of the floating resistor is controlled within a wide range of resistance in between ± 43 Ω – ± 516 kΩ. DOI: http://dx.doi.org/10.5755/j01.eee.19.4.1310