Showing papers on "RC circuit published in 2015"

A Cascode Miller-Compensated Three-Stage Amplifier With Local Impedance Attenuation for Optimized Complex-Pole Control

Abstract: This work presents a power- and area-efficient three-stage amplifier that is able to drive a large capacitive load. Removing the inner Miller capacitor and employing cascode Miller compensation in the outer compensation loop could extend the complex-pole frequency of a three-stage amplifier, but result in a high Q-factor. A local impedance attenuation block consisting of a series RC network is proposed to control the complex poles. This block attenuates the high-frequency resistance at the second-stage output and achieves an optimized tradeoff between the frequency and the Q-factor of the complex poles. As the low-frequency resistance remains unchanged, a high dc gain is maintained. Implemented in 0.13 $\mu$ m CMOS process, the proposed design occupies an area of 0.0032 mm 2 and consumes a quiescent current of 10.5 $\mu$ A. When driving a 560 pF capacitive load, it achieves a unity-gain frequency of 3.49 MHz, an average slew rate of 0.86 V/ $\mu$ s, and an average settling time of 0.9 $\mu$ s.

Class AB tunable active inductor

Abstract: A class AB active inductor with high linearity, including a minimum number of components, is presented. Class AB operation is absent from the literature on the design of active inductors but is addressed in this reported work. Circuit details are given. A prototype board on a TLX8 substrate has been fabricated and tested showing the circuit feasibility for use in many commercial market applications, as integrated circuits, or discrete filters and oscillators.

Investigation of electrical RC circuit within the framework of fractional calculus

Abstract: In this paper, charging and discharging processes of different capacitors in electrical RC circuit are considered theoretically and experimentally. The non-local behaviors in these processes, arising from the time fractality, are investigated via fractional calculus. In this context, the time fractional differential equation related to electrical RC circuit is proposed by making use of Caputo fractional derivative. The resulting solution exhibits a feature in between power law and exponential law forms, and is obtained in terms of Mittag-Leffler function which describes physical systems with memory. The order of fractional derivative characterizes the fractality of time and being considered in the interval 0 < fi • 1. The traditional conclusions are recovered for fi = 1, where time becomes homogenous and system has Markovian nature. By using time fractional approach, the discrepancies between the experimentally measured data and the theoretical calculations have been removed.

An Arduino Investigation of the RC Circuit

Abstract: The experimental investigation of the charging or discharging of a capacitor through a resistor is of fundamental importance to the study of electricity. Students taking the Physics SAT or the AP Physics C: Electricity and Magnetism test have to prove their knowledge of time-varying behavior in RC circuits. While the classical experiment is done using a voltmeter and a stopwatch, this procedure is tedious and prone to human errors. We have developed an alternative procedure in which the voltage, the current, and the time are all measured electronically with the help of an Arduino Uno microcontroller board.

Correlation of the impedance and effective electrode area of doped PEDOT modified electrodes for brain–machine interfaces

Abstract: Electrode impedance is used to assess the thermal noise and signal-to-noise ratio for brain-machine interfaces. An intermediate frequency of 1 kHz is typically measured, although other frequencies may be better predictors of device performance. PEDOT-PSS, PEDOT-DBSA and PEDOT-pTs conducting polymer modified electrodes have reduced impedance at 1 kHz compared to bare metal electrodes, but have no correlation with the effective electrode area. Analytical solutions to impedance indicate that all low-intermediate frequencies can be used to compare the electrode area at a series RC circuit, typical of an ideal metal electrode in a conductive solution. More complex equivalent circuits can be used for the modified electrodes, with a simplified Randles circuit applied to PEDOT-PSS and PEDOT-pTs and a Randles circuit including a Warburg impedance element for PEDOT-DBSA at 0 V. The impedance and phase angle at low frequencies using both equivalent circuit models is dependent on the electrode area. Low frequencies may therefore provide better predictions of the thermal noise and signal-to-noise ratio at modified electrodes. The coefficient of variation of the PEDOT-pTs impedance at low frequencies was lower than the other conducting polymers, consistent with linear and steady-state electroactive area measurements. There are poor correlations between the impedance and the charge density as they are not ideal metal electrodes.

A Novel Battery State-of-Health Estimation Method for Hybrid Electric Vehicles

Abstract: This paper presents a state-of-health (SOH) estimation method for lithium-ion batteries in electric vehicles, by identifying the bulk capacitance of its equivalent RC circuit model A novel algorithm is discussed to derive the attenuation factor of the bulk capacitance in different cycles A discrete nonlinear observer is also designed so that the bulk capacitance can be successfully identified to realize the estimation of SOH, where the established nonlinear system is discretized directly at the sample time to improve the modeling accuracy and reliability Three experimental results demonstrate the effectiveness of the proposed method

Equivalent circuit modeling of the ac response of Pd-ZrO2 granular metal thin films using impedance spectroscopy

Abstract: The ac response in the dielectric regime of thin films consisting of Pd nanoparticles embedded in a ZrO2 insulating matrix, fabricated by co-sputtering, was obtained from impedance spectroscopy measurements (11?Hz?2?MHz) in the temperature range 30?290?K. The response was fitted to an equivalent circuit model whose parameters were evaluated assuming that, as a consequence of the bimodal size distribution of the Pd particles, two mechanisms appear. At low frequencies, a first element similar to a parallel RC circuit dominates the response, due to two competing paths. One of them is associated with thermally-activated tunneling conductance among most of the smallest Pd particles (size ~ 2?nm), which make up the dc tunneling backbone of the sample. The other one is related to the conductance associated with the capacitive paths among larger Pd particles (size??>??5?nm). At low temperature and intermediate frequencies (~1?kHz), a shortcut process between the larger particles connects regions initially isolated from the backbone at low frequencies. These regions, populated by some additional smaller particles located around two bigger particles, were isolated because the bigger particles separation is too large for the tunneling current. Once connected to the backbone, current may also flow through them by means of the so-called thermally-activated assisted tunneling resistive paths, yielding the second element of the equivalent circuit (a parallel RLC element). At high temperature, the thermal energy shifts the onset of the shortcut process high frequencies and, thus, only the first element is observed. Considering these results, controlling the particle size distribution could be helpful to tune up the frequency at which tunneling conductance dominates the ac response of these granular metals.

Neural network circuit and learning method for neural network circuit

Abstract: A neural network circuit includes an error calculating circuit that generates an error voltage signal having a magnitude in accordance with a time difference between an output signal and a teaching signal corresponding to the output signal. A weight change pulse voltage signal is input to a synapse circuit of a neural network circuit element including a neuron circuit that output the weight change pulse voltage signal, and a switching pulse voltage signal is input to a synapse circuit of a neural network circuit element other than the neural network circuit element including the neuron circuit that output the switching pulse voltage signal. The neural network circuit element changes the amplitude of the weight change pulse voltage signal on the basis of the error voltage signal generated by the error calculating circuit.

Neural network circuit and learning method thereof

Abstract: In a neural network circuit element, a neuron circuit includes a waveform generating circuit for generating an analog pulse voltage, and a switching pulse voltage which is input as a first input signal to another neural network circuit element; a synapse circuit is configured such that the analog pulse voltage generated in the neuron circuit of the neural network circuit element including the synapse circuit is input to a third terminal of a variable resistance element of the synapse circuit, for a permissible input period, in the first input signal from another neural network circuit element; and the synapse circuit is configured such that the resistance value of the variable resistance element is changed in response to an electric potential difference between a first terminal and the third terminal, which occurs depending on a magnitude of the analog pulse voltage for the permissible input period.

A Time-Mode Translinear Principle for Nonlinear Analog Computation

Abstract: This work proposes a novel translinear principle based on time domain processing of signals. The exponential relationship between voltage and time in an RC circuit is exploited to implement a logarithmic voltage-to-time converter and an exponential time-to-voltage converter. These circuits are the time domain analogs of the voltage mode translinear circuits that exploit the exponential relationship between current and voltage in BJTs and subthreshold MOS transistors. Just as Kirchoff's voltage laws provide a natural form of addition for the voltage-mode translinear principle, the progression of time can also be a natural source of addition for the proposed time-mode analog of this principle. In this work a time-mode adder circuit is used to realize a translinear principle in time. This paper describes the theory behind this time-mode translinear principle. Furthermore, the design of nonlinear circuit functions, e.g., multiplication and power law, based on the time-mode translinear principle is described. Simulation and measurement results for a two-input single quadrant multiplier are presented. The chip was fabricated in a 180 nm CMOS process with simulation results agreeing closely with experimental results. We also present error analysis for such circuits and provide a brief discussion on future prospects of this approach.

Lithium-battery variable fractional order and equivalent circuit model and identification method thereof

Abstract: The invention discloses a lithium-battery variable fractional order and equivalent circuit model and an identification method thereof. The lithium-battery variable fractional order and equivalent circuit comprises a run time circuit and a battery I-V characteristic circuit, wherein a capacitor in the battery I-V characteristic circuit is a variable fractional order capacitor. A second order RC circuit model is generalized to a non-integer order, and the model parameters and the number of fractional order of different SOC are identified based on a least square method, so that the fractional order and equivalent circuit varying order according to the SOC is obtained. The instruction of fractional order realizes the continuous change of the order number of the model, so that the model is relatively stable, good in dynamic property and high in precision. The variation of fractional order realizes more freedom and more flexibility and innovation of the model. As the number of RC networks is not increased, the fractional order model effectively solves the contradiction between the accuracy and practicality of the model, is suitable for various working conditions of batteries, and has high practical value. The invention provides a precise battery model easy to realize for precise estimation of SOC.

A novel driving scheme for synchronous rectifier in MHz CRM flyback converter with GaN devices

Abstract: Synchronous rectifier (SR) is widely used in flyback converter to reduce the output side conduction loss in order to meet the system conversion efficiency requirement. The conventional SR driving methods are not suitable for high frequency (>500kHz) application. This paper proposes a novel SR driving method for MHz flyback converter operating at critical conduction mode (CRM). A RC network is in parallel with SR to emulate the magnetizing current of flyback converter. The sensing signal is clean and immune to the parasitic ringing caused by the leakage inductance and parasitic capacitors. SR gate signal is accurately generated based on a simple signal processing circuit and the conduction loss of SR body diode is minimized. The theoretical analysis is validated by simulation and experiment.

Design of RC circuit as partial discharge detector

Abstract: Partial discharge (PD) is the main cause of the failure of power apparatus insulation. The detection of PD in the early stage is useful to understand the condition of power apparatus, to design predictive maintenance program, and to prevent the breakdown of power apparatus. PD signal can be detected by the sensor. This paper deals with design of resistor capacitor (RC) circuit as PD detector. The PD detector was tested using a vector network analyzer. The bandwidth, the return loss, and the resonance frequency of the detection circuit were measured. The testing results show that the bandwidth of RC detector achieved 500 MHz. The PD detector was applied to measure PD occurring in the air insulation of needle-plane electrode. The measured PD parameters were PD inception voltage (PDIV), PD waveform PD, PD phase pattern, and PD pulse sequence. The testing results show that PD detector is able to measure PD.

Bidirectional scanning GOA circuit

Abstract: A GOA circuit for use in LCD applications is disclosed, and the GOA circuit includes multiple cascaded GOA units, each of which includes a pull-up control circuit, a pull-up circuit, a pull down circuit, a pull-down holding circuit, a reset circuit, and a bootstrap capacitor. By using the GOA circuit, scanning directions of the LCD display panel are controlled by introducing scanning control signals to the pull-up control circuit for determining to output gate signals of the GOA circuit in sequence of up-to-down stages or in sequence of down-to-up stages. Furthermore, a novel scheme of three-segment voltage division achieves the optimization and the stability of the GOA circuit.

Overvoltage mitigation in open-end winding AC motor drives

Abstract: An over-voltage mitigation technique for open-end winding electrical drives with long power cables is proposed in this paper. In particular, a suitable dwell time is included in the switching patterns of the two inverters to minimize the over-voltage occurring at the stator terminals of this kind of systems. No passive RLC networks are required, thus avoiding additional costs and extra power losses. The proposed approach is first theoretically introduced, then validated by numerical simulations and experimental tests. Finally its effectiveness is compared with that of conventional passive RC filters.

Switch failure monitoring in an electrically heated smoking system

Abstract: There is provided a method of controlling an electric heater (14) in an electrically heated smoking system, the method comprising: providing electrical power to the heater in pulses such that during an active periods power is supplied to the heater and during inactive periods power is not supplied to the heater; charging a capacitor(52) in an RC circuit (36) during inactive periods and allowing the capacitor to discharge during active periods; and monitoring a discharge voltage of the capacitor and if the discharge voltage of the capacitor drops below a threshold voltage level, then stopping further supply of electrical power to the heater. This method allows for consistent and reliable detection of a switch failure using compact and low power components.

Design of a symmetry-type floating impedance scaling circuits for a fully differential filter

Abstract: Low frequency and low power applications are required for biomedical devices. Thus, a large capacitance is needed for integration of low frequency active filters. To realize a small-size low frequency active filter, impedance scaling techniques have been proposed. In this paper, a symmetry-type floating impedance scaling circuit is proposed. The proposed circuit is composed of voltage followers and current amplifiers. The characteristics of the proposed circuit are confirmed by simulation. The proposed circuit works as a large capacitor which has a capacitance multiplied 50 times. The proposed circuit is applied to a fully differential 3rd-order low-pass filter. Simulation results show validities and availability of the proposed symmetry-type floating impedance scaling circuit.

Comparison of two battery equivalent circuit models for state of charge estimation in electric vehicles

Abstract: This study compares two battery equivalent circuits for state of charge (SOC) estimation in electric vehicles (EVs), namely the RC circuit and Thevenin circuit. The state space representations of each circuit are used to develop the adaptive gain sliding mode observers (AGSMO) for the SOC estimations, which are compared with the true SOC. The results show that the Thevenin circuit provides more accurate SOC estimation than the RC circuit. A lithium-ion battery is chosen for experimental verification under constant current discharge and variable current discharge based on EV driving cycles.

Power factor correction circuit with digital control scheme and associated control method

Abstract: A PFC circuit having a switching circuit and a control circuit, the control circuit controls an operation mode of the switching circuit based on an input current and a switching frequency of the switching circuit, when the switching circuit works under a continuous current mode, the switching circuit is turned ON when the input current is less than an OFF current reference signal, and when the switching circuit works under a first discontinuous mode or a second discontinuous mode, the switching circuit is turned ON after a turn ON delay time period when the input current is less than the OFF current reference signal.

Analysis of frequency dispersion in amorphous In–Ga–Zn–O thin-film transistors

Abstract: It is shown in this paper that the finite resistance of the accumulation channel in amorphous In–Ga–Zn–O thin-film transistors (a-IGZO TFTs) is the main cause of the frequency dispersion of the capacitance–voltage curves in these devices. A transmission line model, accounting for the distributed nature of channel resistance, is used to explain this. Multi-frequency analysis techniques for trap density distribution use a lumped series resistance model and attribute dispersion solely to the charging and discharging of trap states. As the resistance–capacitance (RC) time constant values of the IGZO TFTs are in the range of 10–100 µs, a distributed RC network is better suited for the measured frequency range (1 kHz–1 MHz). cop. 2014 The Korean Information Display Society.

Dcr inductor current-sensing in four-switch buck-boost converters

Abstract: An inductor current-sensing circuit for measuring a current in an inductor includes (a) a first RC network coupled between a first terminal of the inductor and a reference voltage source; and (b) a second RC network coupled between a second terminal of the inductor and the reference voltage source. The first RC network and the second RC network each have a time constant substantially equal to the ratio between the inductance and the DC resistance of the inductor. The inductor which current is being measured may be a primary inductor of a four-switch buck boost converter receiving an input voltage and providing an output voltage.

Single op-amp second-order loop filter for continuous-time delta–sigma modulators

Abstract: A second-order loop filter (LF) that uses a single op-amp resonator is presented for continuous-time delta–sigma modulators. The proposed technique improves the power and area efficiency of the LF and enhances the controllability of the transfer function and the resonating condition by providing a new RC network. A second-order modulator has been designed to confirm the effectiveness of the proposed scheme. Implemented in a 130 nm CMOS, the prototype modulator occupies an active area of 0.098 mm2 and consumes 5.23 mW power from a 1.2 V supply. It achieves a peak SNDR of 60.95 dB over a 15 MHz signal bandwidth with a sampling frequency of 780 MHz.

Universal low-frequency asymptotes of dynamic conic nanopore rectification: An ionic nanofluidic inductor

Abstract: We report the first nanofluidic inductor (L) to complement the known nanofluidic capacitors (C), resistors (R), and diodes for ion currents. Under negative bias, the nanopore behaves like a parallel RC circuit at low frequencies; however, under positive bias, the asymptotic dynamics is that of a serial RL circuit. This new ionic circuit element can lead to nanofluidic RLC or diode-inductor oscillator circuits and new intrapore biosensing/rapid sequencing strategies. A universal theory, with explicit estimates for the capacitance and inductance at opposite biases, is derived to collapse the rectified dynamics of all conic nanopores to facilitate design of this new nanofluidic circuit.

Small-Signal Modeling of Marine Electromagnetic Detection Transmitter Controlled-Source Circuit

Abstract: Marine electromagnetic transmitter transmits electromagnetic waves with large power frequency conversion to the seabed to obtain the submarine structure and mineral resources. However, the current transmitter presents several problems, such as low efficiency, serious heat, and poor adaptability to the load. Soft-switching controlled-source circuit is used to reduce circuit losses. The mathematical model of controlled-source circuit should be established to realize a closed-loop control for increasing the output transient performance of electromagnetic waves. Given that the soft-switching controlled-source circuit has more status and that direct modeling is difficult, small-signal model of soft-switching controlled-source circuit is established based on that of hard-switching controlled-source circuit by analyzing the effect of output filter inductor current transformer leakage inductance and input voltage soft-switching controlled circuit on change in the duty cycle. Finally, experiments verify the accuracy and validity of the model.

Energy harvester open-circuit voltage sensing for MPPT

Abstract: Apparatus and techniques described herein can include using an electronic circuit comprising a rectifier circuit, an open-circuit voltage (OCV) sampling circuit coupled to the output of the rectifier circuit, and a regulator circuit coupled to the output of the rectifier circuit. In an example, an isolation switch can be located between the regulator circuit and the rectifier circuit, the isolation switch configured to isolate the regulator circuit from the rectifier circuit for sampling of the open-circuit voltage by the open-circuit voltage sampling circuit. In another example, a buffer circuit can be used, such as placed in-line with a divider circuit between a divider circuit and an open-circuit voltage sampling capacitor. In this manner, the buffer circuit can provide a low output impedance, isolating the voltage sampling capacitor from the divider circuit.

Voltage mode implementation of highly accurate analog multiplier circuit

Abstract: A new four-quadrant multiplier circuit is presented in this paper. Compared to the corresponding already published works, the accuracy of the circuit as well as the linearity performance is significantly improved. DC transfer characteristic of the circuit shows the nonlinearity error of 1.1% over a considerable range of the inputs. The performance of the circuit, in terms of the conceivable mismatch in trans-conductance parameter and threshold voltage are thoroughly analyzed. The circuit is simulated using HSPICE with TSMC level 49 (BSIM3v3) parameters for 0.18 μm CMOS technology, where under supply voltage of 1.8 V the −3 dB bandwidth of the proposed circuit is 1.45 GHz and the total harmonic distortion at 1 MHz, remains as low as 0.4 %.