Showing papers on "RC circuit published in 2014"

Online Adaptive Parameter Identification and State-of-Charge Coestimation for Lithium-Polymer Battery Cells

Abstract: Real-time estimation of the state of charge (SOC) of the battery is a crucial need in the growing fields of plug-in hybrid electric vehicles and smart grid applications. The accuracy of the estimation algorithm directly depends on the accuracy of the model used to describe the characteristics of the battery. Considering a resistance-capacitance (RC)-equivalent circuit to model the battery dynamics, we use a piecewise linear approximation with varying coefficients to describe the inherently nonlinear relationship between the open-circuit voltage (VOC) and the SOC of the battery. Several experimental test results on lithium (Li)-polymer batteries show that not only do the VOC-SOC relationship coefficients vary with the SOC and charging/discharging rates but also the RC parameters vary with them as well. The moving window least squares parameter-identification technique was validated by both data obtained from a simulated battery model and experimental data. The necessity of updating the parameters is evaluated using observers with updating and nonupdating parameters. Finally, the SOC coestimation method is compared with the existing well-known SOC estimation approaches in terms of performance and accuracy of estimation.

Investigation of Conducted EMI in SiC JFET Inverters Using Separated Heat Sinks

Abstract: This paper systematically investigates the conducted electromagnetic interference (EMI) using separated heat sinks for a silicon carbide (SiC) JFET inverter for motor drives. The inverter circuit layout is implemented with discrete SiC JFETs attached on top of the heat sink, which creates extensive capacitive couplings and moreover increases parasitic oscillations. To minimize the influence, the solution of using separated heat sinks is proposed. For better common mode performance, the high-side heat sink is grounded to avoid fast dv/dts that occur between the drain of the lower switch and the low-side heat sink. For better differential mode performance, the RC snubber circuit and ferrite beads are used to damp parasitic oscillations. Two 2.2 kW inverter prototypes, with six discrete SiC JFETs on one common heat sink and separated heat sinks, respectively, are built using the same circuit layout. Their EMI spectra are compared under unfiltered and filtered conditions. The experiments show that the separate heat sinks inverter system exhibits significantly reduced EMI. Last, three improved solutions are proposed, which effectively suppresses the emitted EMI to the target level.

Ldo and load switch supporting a wide range of load capacitance

Abstract: An architecture and method to maintain stability of a low drop-out (LDO)/load switch linear voltage regulator (LVR). The architecture method support optionally determining during a power-up phase and by using a load detection circuit, the estimated load parameters that represents at least one selected from a group consisting of: the load time constant and the load resistor at an output node of the LDO/load switch LVR, and adjusting, based on the estimated output load parameters, an adaptive RC network in the LDO/load switch LVR, wherein the adaptive RC network produces an adaptive zero in a feedback network transfer function of the LDO/load switch LVR, wherein the adaptive zero reduces an effect of a non-dominant pole in the open loop transfer function of the LDO/load switch LVR, and wherein a frequency of the adaptive zero is adjusted based on the estimated load parameters.

Optimization of Transmission Conditions in Waveform Relaxation Techniques for RC Circuits

Abstract: Waveform relaxation techniques have become increasingly important with the wide availability of parallel computers with a large number of processors. A limiting factor for classical waveform relaxation, however, is the convergence speed for an important class of problems, especially if long time windows are considered. In contrast, the optimized waveform relaxation algorithm discussed in this paper is well suited to address this problem. Today several numerical analyses have shown that optimized waveform relaxation algorithms can overcome slow convergence over long time windows. However, the optimized waveform relaxation techniques require the determination of optimized parameters. In this paper, we present a theoretical foundation for the determination of the optimized parameters for an important class of RC circuits.

Light-emitting diode driving apparatus and semiconductor device

Abstract: Provided is a light-emitting diode driving apparatus including: a rectifying circuit; a switching element; a choke coil; an output current sensing circuit; an LED light source; a rectifier diode; a control circuit; a feedback sensing circuit; an input voltage sensing circuit; and a conduction time counting circuit, wherein the feedback sensing circuit outputs a feedback dummy current to the output current sensing circuit, the conduction time counting circuit adjusts the feedback dummy current, the feedback sensing circuit outputs to the control circuit a control signal which controls switching of the switching element in response to a signal based on an error between an output feedback signal and a feedback dummy signal generated by the feedback dummy current.

Single Transistor Active Filters: What is Possible and What is Not

Abstract: This paper systematically investigates the design of single transistor second-order active filters out-lining all possible architectures and possible impedance settings using an exhaustive MAPLE search code for all stable cases with the minimum number of passive elements (two resistors and two energy storage elements). The search is performed on six general voltage-input voltage-output transfer functions, derived using a small-signal two-port network transistor model. Selected LC and RC filter designs are verified experimentally. The results presented here fill both a circuit-theoretic gap and an application-oriented gap related to single transistor filter design which, apart from a few examples in the literature, has not been rigorously addressed.

Advanced control circuit for switched-mode DC-DC converter

Abstract: A circuit for controlling a switched-mode DC-DC converter. An inductor is connected between a switching node and an output node, and an output capacitor is connected in series with the inductor. An RC circuit is connected in parallel with the inductor to compensate for ripple voltage. In a discontinuous current mode, a pulse is applied to the switching node and then removed. In this mode, an RC time constant for the RC circuit is increased during the falling edge of a difference signal such that the difference signal does not drop below zero.

Compact model of power MOSFET with temperature dependent Cauer RC network for more accurate thermal simulations

Abstract: A new, more accurate SPICE-like model of a power MOSFET containing a temperature dependent thermal network is described. The designed electro-thermal MOSFET model consists of several parts which represent different transistor behavior under different conditions such as reverse bias, avalanche breakdown and others. The designed model is able to simulate destruction of the device as thermal runaway and/or overcurrent destruction during the switching process of a wide variety of inductive loads. Modified thermal equivalent circuit diagrams were designed taking into account temperature dependence of thermal resistivity. The potential and limitations of the new models are presented and analyzed. The new model is compared with the standard and empirical models and brings a higher accuracy for rapid heating pulses. An unclamped inductive switching (UIS) test as a stressful condition was used to verify the proper behavior of the designed MOSFET model.

A comparative study on RC models of lithium-ion battery

Abstract: In the rest, two equivalent circuit models, the first-order resistance-capacitance (RC) model and the second-order RC model, were investigated for a lithium-ion battery. The Gauss-Newton (G-N) least square was applied to identify the two model parameters because of its nonlinear estimation and iteration. The lithium-ion battery rested respectively at three SOC points as 20%, 50%, and 80%. Results show that the second-order RC model presents better approximation for the real battery terminal voltage than the first-order whether the battery charges or discharges.

Trantanella Wilkinson power divider with additional transmission lines for simple layout

Abstract: By adding extra transmission lines between 90° transmission lines at an arbitrary phase angle from the input terminal, a modified Trantanella Wilkinson power divider with a simple layout is presented. Design equations for characteristic impedances and complex isolation components are derived from even- and odd-mode analysis. Parallel and series RC circuits are chosen to realise the complex isolation components, and bandwidths are also discussed. For both parallel and series RC circuits, two experimental circuits were fabricated under the same conditions. The experimental results showed good agreement with the results of simulation.

Comparator and amplifier

Abstract: A comparator has a differential pair circuit and a current control circuit. The differential pair circuit has first and second comparator transistors, and is arranged to compare a first input and a second input according to a clock signal to generate a result indicating whether a difference of the first and second inputs exceeds an internal offset. The current control circuit is coupled in series with the differential pair circuit, and configured to provide unequal abilities of drawing currents for the first and second comparator transistors. An amplifier circuit is also disclosed, having a differential pair circuit, a current control circuit, an amplification circuit and a reset circuit.

Intrinsic Performance of InAs Nanowire Capacitors

Abstract: The intrinsic properties of vertical InAs nanowire (NW) capacitors are investigated. The band structure is simulated using a Schrodinger-Poisson solver, taking the conduction band nonparabolicity into account. This is combined with a distributed RC model to simulate the current-voltage characteristics. It is found that the influence from the nonparabolicity is substantial for devices with a small nanowire diameter, resulting in an increased carrier concentration, a shift in the threshold voltage, and a higher intrinsic capacitance. These NW capacitors may be a suitable alternative in high frequency applications approaching 100 GHz, while maintaining a quality factor above 100.

Display device of active matrix type

Abstract: A display device of active matrix type allows reducing display brightness non-uniformity that is caused by initial variation and fluctuation over time in a driving transistor for emissive elements in pixel circuits The display device includes pixel circuits, a measurement circuit and a gradation voltage supplying circuit Each pixel circuit includes the driving transistor and an input circuit The measurement circuit includes a constant current supplying circuit for generating and supplying one or more constant currents to the input circuit of the pixel circuits in a time division manner The measurement circuit A/D-converts output voltages of the constant current supplying circuit and calculates data relating to electron mobility and threshold value of the driving transistor The gradation voltage supplying circuit supplies to the pixel circuits a corrected gradation voltage, which is data corrected on the basis of data calculated from the measurement circuit

Signal processing circuit, signal processing method, position detector, and electronic device

Abstract: A signal processing circuit is connected to one of a plurality of conductors of a position detection sensor having a self-capacitance and configured to generate a signal indicative of the self-capacitance for use in correcting a pointer position detection signal. The circuit includes a capacitor circuit and detects a change in capacitance between the conductor and a pointer (e.g., a finger) as a change in voltage in the capacitor circuit. The signal processing circuit further includes: a gate circuit which controls the connection between the capacitor circuit and the conductor; and a voltage supply control circuit which temporarily sets, to a defined voltage level, a first end of the gate circuit to which the conductor is connected and sets a defined potential difference between the first end and another (second) end of the gate circuit to which the capacitor circuit is connected.

Analog-to-digital converter circuits and methods

Abstract: An analog-to-digital converter circuit includes a digital-to-analog converter circuit, a voltage stabilization circuit, and a comparator circuit. The digital-to-analog converter circuit generates an analog signal based on digital signals and a reference voltage. The voltage stabilization circuit reduces variations in the reference voltage in response to at least one of the digital signals. The comparator circuit generates a comparison output based on the analog signal. The digital signals are generated based on the comparison output.

Electromagnetic input device

Abstract: An electromagnetic input device comprises a protruding part, a pressure-sensitive module, a conductive module, and a control unit. The pressure-sensitive module comprises a circuit board and a capacitor. One surface of the circuit board is provided with a printed carbon film resistor. The capacitor is disposed on the circuit board. The capacitor and the carob film resistor form an RC circuit which has a time constant. The conductive module is connected with the protruding part. At least part of the conductive module is used for contacting with the carbon film resistor. Resistance of the carbon film resistor changes with changes in contact area of the conductive module with the carbon film resistor, so that the time constant changes correspondingly. The control unit is electrically connected with the RC circuit and used for detecting the time constant. When bearing external force, the protruding part drives the conductive module to move, the contact area of the conductive module with the carbon film resistor changes, the time constant changes along, and the control unit controls input line width of the electromagnetic input device according to the time constant. Through the application of the electromagnetic input device, the problems that the pressure-sensitive measuring component is complex to manufacture and low in sensing sensitiveness can be improved.

Synchronized Zero-Crossing-Based Self-Tuning Capacitor Time-Constant Estimator for Low-Power Digitally Controlled DC–DC Converters

Abstract: A hardware efficient method and system for estimating the time constant and measuring the current of the output capacitors in digitally controlled switch-mode power supplies is introduced. The estimator emulates the equivalent RC circuit of the output capacitor with a much smaller version, placed in parallel, and adjusts its own resistance until the two circuits have the same time constant. The adjustment is based on a novel zero voltage crossing detection method and on synchronization with the digital pulse-width modulator operation. The effectiveness of the new estimator is verified with a 5 V to 1 V/5 A, 500-kHz buck converter prototype utilizing an optimal response controller. The experimental results show accuracy within a few tens of nanoseconds in the detection of capacitor zero-current crossing points, corresponding to a smaller than a 1.5% error in the time constant estimation, and, compared to an imperfectly tuned system, about 40% smaller voltage deviation during transients.

Apparatus and method for current sharing in a multi-phase switching regulator

Abstract: An apparatus and method for a multi-phase switch regulator with improved efficiency is disclosed. The device has parallel implementations for the different phases comprising a driver, a current sense variable gain amplifier, a current share circuit, a pulse width modulation (PWM) control circuit, a trim network, and an inductor. A method is disclosed of providing a system with current sharing function comprising a driver circuit, a current sense circuit, a current share circuit, a PWM control circuit and a trim circuit, providing a current sense circuit for each segment of a driver circuit, sensing a signal using a current sense circuit for each segment of a driver circuit, comparing the output of the current sense circuit, providing the current error information to a PWM controller, generating a PWM drive signal of each phase, and finally, equalizing the output of the current sense amplifier. Other methods that utilize dummy output stages and low pass filter feedback is disclosed.

A three-arm current comparator bridge, for impedance comparisons over the complex plane

Abstract: We present here the concept of three-arm current comparator impedance bridge, which allows comparisons among three unlike impedances. Its purpose is the calibration of impedances having arbitrary phase angles, against calibrated nearly-pure impedances. An analysis of the bridge optimal setting and proper operation is presented. To test the concept, a two terminal-pair digitally-assisted bridge has been realized; measurements of an air-core inductor and of an RC network versus decade resistance and capacitance standards, at kHz frequency, have been performed. The bridge measurements are compatible with previous knowledge of the standards' values with relative deviations in the 10^-5 -- 10^-6 range.

A quantum magnetic RC circuit

Abstract: We propose a setup that is the spin analog of the charge-based quantum RC circuit. We define and compute the spin capacitance and the spin resistance of the circuit for both ferromagnetic (FM) and antiferromagnetic (AF) systems. We find that the antiferromagnetic setup has universal properties, but the ferromagnetic setup does not. We discuss how to use the proposed setup as a quantum source of spin excitations, and put forward a possible experimental realization using ultracold atoms in optical lattices.

Method and apparatus of a self-biased RC oscillator and ramp generator

Abstract: A self-biased RC (resistor-capacitor) oscillator and ramp generator circuit includes a combined current and voltage reference circuit for providing a reference current, a first reference voltage, and a second reference voltage. The combined current and voltage reference circuit includes a circuit branch of an NMOS transistor in a diode connection, a PMOS transistor in a diode connection, and a resistor coupled in series. The circuit also has a signal generating circuit that includes a capacitor. The signal generating circuit is configured to charge and discharge the capacitor between the first reference voltage and the second reference voltage. The self-biased RC oscillator and ramp generator circuit is configured to provide a ramp or saw tooth signal at a node of the capacitor and to provide an oscillator output signal at an output of the signal generating circuit.

Nonlinear Equivalent-Circuit Modeling of a Fast Photodiode

Abstract: A new nonlinear equivalent circuit model of a photodiode is proposed to describe the conversion of the laser relative intensity noise to microwave phase noise. This conversion is realized through a nonlinear RC circuit. The validity of this model has been confirmed by the good agreement between simulation and experimental results at different microwave frequencies. These simulations have been performed using commercially available harmonic balance simulation software.

Modeling and autotuning of AVP control with inductor DCR current sensing

Abstract: A new equivalent circuit model is presented to predict the small-signal characteristic of current-mode control with DCR current sensing accurately, and a simple auto-tuning method is proposed to solve the issue of time constant mismatch in DCR current sensing. The model shows that the mismatch between the current sensing RC network and the output inductor makes the output impedance deviate away from desired load-line resistance, so the transient response impairs. Adding more output capacitors can avoid transient spike, but increase component cost. Prior autotuning method solves mismatch issue by adjusting the time constant of RC network close to another such that output capacitors can be reduced, but the implementation is too complex for monolithically integration. Therefore, this paper develops a simple pole-zero compensation technique to maintain constant output impedance and fast transient under possible mismatch conditions, so output capacitor can be minimized with simpler autotuning circuit on VR controller. The SIMPLIS simulation with state-of-art output filter model of laptop VR and the experiment result on a commercial VR12 controller confirms the effectiveness of the proposed autotuning method.

Differential signal driving circuit

Abstract: A differential driving circuit includes a source current source, a sink current source, an H-bridge circuit, an error detector unit and a circuit network. The H-bridge circuit is connected to the source current source and the sink current source, that has a first output terminal and a second output terminal, and that generates differential output from the first output terminal and the second output terminal. The error detector unit adjusts a common mode voltage at the first output terminal and the second output terminal of the H-bridge circuit by controlling at least one of the source current source and the sink current source. The circuit network is configured by resistors and capacitors connected to the first output terminal and the second output terminal of the H-bridge circuit.

Light emitting device power supply circuit and damping circuit therein and driving method thereof

Abstract: The present invention discloses a light emitting device power supply circuit and a damping circuit therein and a driving method thereof. The light emitting device power supply circuit includes: a tri-electrode AC switch (TRIAC) dimming circuit, a rectifier circuit, a light emitting device driver circuit, and a damping circuit. The damping circuit includes: an impedance circuit, which is electrically connected between the rectifier circuit and the light emitting device driver circuit; a silicon control rectifier (SCR) circuit, which is connected to the impedance circuit in parallel; and a delay circuit, which is coupled to the SCR circuit, for turning ON the SCR circuit after a delay time period from when the TRIAC diming circuit begins to start-up, wherein the delay circuit does not directly receive a full scale of the input voltage.

Extraction of Poles and Zeros of an $RC$ Circuit With Roots on the Real Axis

Abstract: A graphical/numerical technique is presented for the extraction of roots (poles and zeros) of an RC circuit, where the roots lay on the left-hand side of the real axis (RLHP) in the s-plane. The method constructs a corresponding LC circuit for the RC circuit and, as shown, all the RLHP roots in the RC circuit are shifted to the jω axis, where the swiping-frequency signals exist. It is also shown that the magnitude of the corresponding roots in the two circuits are related by a scaling factor. The technique is also extended to study the behavior of real-axis RHP roots in RC circuits. Several examples demonstrate the performance of the proposed technique.

Switching voltage regulator noise coupling to connector signal pins through near field radiation

Abstract: In a server system, the switching voltage regulator (VR) noise coupled to the IO pins of the adjacent memory riser connector through the open air above the base board, and the link performance was impacted by the coupling. A simulation flow was developed to reproduce this EMI phenomenon. The flow first used electromagnetic field solvers to extract the VR related power network and the VR-IO coupling network, and then the di/dt and dv/dt noise sources and the induced IO noise were solved in HSpice®. The simulation revealed the underlying coupling mechanism: The high frequency current loop formed by the power MOSFET, the VR power shapes, the snubber RC circuit at the bottom layer of the board, and the stitching via acted as a transmitting loop antenna, and the radiating field propagated through the air and was picked up by another loop (receiving antenna) formed by the riser connector pins. An effective mitigation method is to use bigger snubber resistor to damp this near field radiation. Both the coupling theory and the effectiveness of the mitigation method were proved by the measurements.

Programmable stabilization network

Abstract: The present disclosure includes programmable stabilization circuits and methods. In one embodiment, a power amplifier in a wireless transmitter includes a transistor comprising a gate, a source, and a drain. Feedback from the drain to the gate is modified dynamically to stabilize the amplifier under changing operating conditions. In one embodiment, a series RC circuit is configured between the drain the gate and the RC circuit value is adjusted based on different power supply voltage modes.

Low power externally biased power-on-reset circuit

Abstract: Various methods and devices that involve power-on-reset (POR) circuits are disclosed herein. An exemplary POR circuit for generating a POR signal upon detecting that a supply voltage has reached a desired level comprises a sense circuit and a delayed buffer. The sense circuit comprises: (i) an inverter powered by a known bias voltage; (ii) a feedback circuit powered by the supply voltage; and (iii) an output node of the sense circuit that experiences a voltage transition when the supply voltage has reached the desired level. The delayed buffer is coupled to the output node of the sense circuit that generates the POR signal in response to the voltage transition. The feedback circuit shuts off the sense circuit in response to the voltage transition. The POR circuit generates the POR signal for a local system. The known bias voltage is provided by an external system.