Showing papers on "RC circuit published in 2009"

Optimal parameters and power characteristics of piezoelectric energy harvesters with an RC circuit

Abstract: A piezoelectric based energy harvesting scheme is proposed here which places a capacitor before the load in the conditioning circuit. It is well known that the impedance between the load and source contributes greatly to the performance of the energy harvesting system. The additional capacitor provides flexibility in achieving the optimal impedance value and can be used to expand the bandwidth of the system. A theoretical model of the system is derived and the response of the system, as a function of both resistance and capacitance, is studied. The analysis shows that the energy harvesting performance is dominated by a bifurcation occurring as the electromechanical coupling increases above a certain value: below this point, the addition of an additional capacitor does not increase the performance of the systems; above it, the maximum power can be achieved at all points between these two bifurcation frequencies. Additionally, it has been found that the optimal capacitance is independent of the optimal resistance. Therefore, the necessary capacitance can be chosen, and then the resistance determined, for providing optimal energy harvesting at the desired frequencies. For systems with low coupling, the optimal added capacitance is negative (additional power to the circuit), indicating that a second capacitor should not be used. For systems with high coupling, the optimal capacitance becomes positive for a range of values between the bifurcation frequencies and can be used to extend the bandwidth of the harvesting system. The analysis also demonstrates that the same maximum energy can be harvested at any frequency; however, outside the two bifurcation frequencies the capacitor must be negative.

Widely Programmable High-Frequency Active RC Filters in CMOS Technology

Abstract: We propose a circuit technique that enables the realization of widely programmable high-frequency active RC filters in CMOS technology. A fifth-order Chebyshev ladder filter having a digitally programmable 3-dB bandwidth (from 44 to 300 MHz) is used as a vehicle to validate our ideas. The opamp uses feedforward compensation for achieving high dc gain and wide bandwidth. The integrating resistors are realized as a series combination of a triode-operated MOSFET and a fixed polysilicon resistor. A charge-pump-based servo loop servoes the integrating resistor to a stable off-chip resistor. The principle of ldquoconstant capacitance scalingrdquo is applied to the opamp and the integrating resistors so that the shape of the frequency response is maintained when the bandwidth is scaled over a 7 times range. The filter core, designed in a 0.18-mum CMOS process, consumes 54 mW from 1.8-V supply and has a dynamic range of 56.6 dB.

Closed loop negative feedback system with low frequency modulated gain

Abstract: A power supply apparatus and method of regulating is provided. A clock generator circuit is configured for generating a clock signal at a predetermined frequency. An amplifier circuit is coupled with the clock generator circuit. The amplifier circuit includes a gain circuit coupled with the clock generator circuit. The amplifier circuit is configured to receive the clock signal at a switching element of the gain circuit. A controller circuit is configured for receiving a modulated error signal of the amplifier circuit and is configured for generating a pulse width modulated signal for controlling a duty cycle of the switching circuit. The switching circuit is configured for receiving the modulated error signal. The error signal is modulated using the clock signal to vary a gain value of the gain circuit according to the predetermined frequency. An output circuit is coupled with the switching circuit and is configured for generating a regulated voltage signal. The controller circuit uses the modulated error signal to substantially reduce harmonic distribution in a switching frequency of the switching circuit. Harmonic distribution in the switching circuit can be reduce by 10.0 db or greater.

Assembled battery total voltage detection circuit

Abstract: An assembled battery total voltage detection circuit includes a main control circuit, a divider resistor connected between a plus terminal and a minus terminal of an assembled battery insulated from the main control circuit, and a differential amplifier circuit that amplifies voltage divided by the divider resistor. A constant electric potential relative to a ground of the main control circuit is applied to a midpoint of the divider resistor. The main control circuit measures the voltage divided by the divider resistor via the differential amplifier circuit.

An on-chip CMOS relaxation oscillator with power averaging feedback using a reference proportional to supply voltage

Abstract: Recently, on-chip reference oscillators are required for low-cost single-chip applications including biomedical sensors, microcomputers, high-speed interfaces such as DDR I/F and HDMI (for initial negotiation), and SoCs. RC oscillators (including relaxation oscillators) were developed to realize on-chip oscillators with standard CMOS processes. In this paper, a power-averaging feedback (PAF) concept for accurate oscillators with low power and small area is presented.

Crystal oscillator for surface mounting

Abstract: A crystal oscillator includes an oscillator circuit, a main body, a first switching circuit, a second switching circuit, and a voltage detecting circuit. The oscillator circuit includes an IC chip including an output circuit and a function circuit. The crystal element includes a first excitation electrode and a second excitation electrode. The main body houses the oscillator circuit and the crystal element and includes a power supply terminal, a ground terminal, an output terminal, and a function terminal. The output terminal is electrically connected to the output circuit and the first excitation electrode via the first switching circuit. The function terminal is electrically connected to the function circuit and the second excitation electrode via the second switching circuit. The first switching circuit and the second switching circuit are operated on the basis of a switching signal from the voltage detecting circuit connected to the power supply terminal.

A 0.5 V bulk-input OTA with improved common-mode feedback for low-frequency filtering applications

Abstract: This paper presents the design of a two-stage pseudo-differential operational transconductance amplifier (OTA) and its application in low-frequency continuous time filters. The OTA was designed in a 0.18 μm, 0.45 V V T CMOS process. An improved bulk-mode common-mode feedback (CMFB) circuit has been designed which does not load the OTA compared to prior art. A self cascode load structure and partial positive feedback provide higher gain. The bulk terminals of all transistors have been biased to lower their threshold voltages (VT) and maximize signal swing. The OTA operates at a supply voltage of 0.5 V and consumes only 28 μW of power. Rail-to-rail input is made possible by using the transistor's bulk terminal as the input. For a load of 20 pF the OTA has a measured DC gain of 63 dB and a gain-bandwidth product of 570 kHz. To demonstrate the use of the OTA in practical circuits, three active RC filters were designed: a 10 kHz Butterworth filter, a 10 kHz Bessel filter, and a 2.5 kHz Tschebycheff filter.

Safety of pulsed electric devices.

Abstract: The strength–duration curve for tissue excitation can be modeled by a parallel resistor–capacitor circuit that has a time constant. We tested several short-duration electric generators: five electric fence energizers, the Taser X26 and a high-frequency generator to determine their current-versus-time waveforms. We estimated their safety characteristics using existing IEC and UL standards for electric fence energizers. The current standards are difficult to follow, with cumbersome calculations, and do not explicitly explain the physiological relevance of the calculated parameters. Hence we propose a new standard. The proposed new standard would consist of a physical RC circuit with a certain time constant. The investigator would discharge the device into a passive resistor–capacitor circuit and measure the resulting maximum voltage. If the maximum voltage does not exceed a limit, the device passes the test.

Temperature detection circuit

Abstract: A temperature detection circuit has a first temperature sensor circuit that outputs a voltage having a negative temperature gradient and an absolute value and a second temperature sensor circuit that outputs a voltage having a positive temperature gradient and the same absolute value as that for the output voltage of the first temperature sensor circuit. A switch circuit conducts a switching operation in accordance with a control signal to switch between outputting the output voltage of the first temperature sensor circuit and the output voltage of the second temperature sensor circuit. A comparison circuit compares the output voltage from the first or second temperature sensor circuit with a reference voltage. A logic circuit outputs a temperature detection signal on the basis of the control signal and an output signal from the comparison circuit.

Novel high-precision current-mode circuits based on the MOS-translinear principle

Abstract: In this paper, a method to reduce the errors generated by the second order effects in the current-mode circuits employing MOS translinear loop is proposed. Using this method a square-root circuit, a squarer/divider circuit and a multiplier/divider circuit are designed and presented. They are suitable for standard CMOS fabrication and analog systems.

Circuit-coupled FEM analysis of the electric-field type intra-body communication channel

Abstract: The electric-field (EF) intra-body communication (IBC) is a promising data transmission method for high-speed low-power biomedical sensors. A good model of the EF-IBC channel is needed for better understanding the signal propagation principle and more efficient IBC transceiver design. Although various effective models have been developed for the waveguide IBC channel, the EF-IBC channel has only been modeled by empirical distributed RC network. In this paper, a circuit-coupled finite-element-method (FEM) model is established to analyze the EF-IBC channel. A multi-layer FEM model is developed for the human forearm. The parasitic effects of the probe PCBs and the return path are modeled as circuit elements. The circuit-coupled FEM model is simulated in ANSYS. Simulation results show that the model agrees well with the EF-IBC measurements. The circuit-coupled FEM model provides useful insights into the EF-IBC mechanism.

Light source driving device

Abstract: A light source driving device includes a power stage circuit, a first transformer circuit, a second transformer circuit, and a feedback control circuit. The power stage circuit converts a received signal to an alternating current (AC) signal, which includes a synchronizing switching bridge arm, a first bridge arm, and a second bridge arm. The synchronizing switching bridge arm has a Soft-Switching function, and forms a first full-bridge circuit with the first bridge arm and forms a second full-bridge circuit with the second bridge arm. The first transformer circuit is connected to the first full-bridge circuit, for converting the AC signal. The second transformer circuit is connected to the second full-bridge circuit, for converting the AC signal. The feedback control circuit is connected between the light source module and the power stage circuit, for controlling output of the power stage circuit.

Synthesis for Negative Group Delay Circuits Using Distributed and Second-Order RC Circuit Configurations

Abstract: This paper describes the characteristic of negative group delay (NGD) circuits for various configurations including first-order, distributed, and second-order RC circuit configurations. This study includes locus, magnitude, and phase characteristics of the NGD circuits. The simplest NGD circuit is available using first-order RC or RL configuration. As an example of distributed circuit configuration, it is verified that losses in a distributed line causes NGD characteristic at higher cut-off band of a coupled four-line bandpass filter. Also, novel wideband NGD circuits using second-order RC configuration, instead of conventional RLC configuration, are proposed. Adding a parallel resistor to a parallel-T filter enables NGD characteristic to it. Also, a Wien-Robinson bridge is modified to have NGD characteristic by controlling the voltage division ratio. They are fabricated on MMIC substrate, and their NGD characteristics are verified with measured results. They have larger insertion loss than multi-stage RLC NGD circuits, however they can realize second-order NGD characteristic without practical implementation of inductors.

Experimental validation of the RC-interconnect effect equalization with negative group delay active circuit in planar hybrid technology

Abstract: This paper deals with the experimental validation of equalization technique of RC-line degradations based on a negative group delay (NGD) active circuit. The feasibility of this method is illustrated by brief theoretical recalls. Formulas permitting the synthesis of this NGD circuit according to the RC-line parameters are proposed. Then, the analytical predictions are verified by experimental results, which also provide evidence the efficacy of the technique for prototypes in planar hybrid technology. So, for an input square-wave pulse of 25 Msym/s-rate, the rise-time and the propagation delay of the regarded RC-circuit were respectively reduced by 71.4% and 86.4%. As expected, the recovered measured signal shows enhancement of both the raising and trailing edges. Finally, the main benefits provided by this technique compared to the use of repeater are discussed.

PWM buck convertor with overcurrent protection function

Abstract: The invention relates to a PWM buck convertor with overcurrent protection function, which comprises a control circuit, a first switching tube connected between an input power source and an inductor, and a current-limit circuit, wherein the current-limit circuit is used for sampling current signals on the first switching tube and outputting overcurrent signals; the control circuit judges whether the overcurrent signals are greater than a preset current maximum to control the connection and cut off of the first switching tube; and the PWM buck convertor is provided with the current-limit circuit, so that a power tube is cut off when the current is increased to the preset current maximum to protect a chip and ensure the normal work of a switch power supply. Furthermore, a capacitor in an RC circuit outputs sampling voltage so as to avoid the influence of power supply voltage vibration on the current-limit circuit in the direct sampling process; when the overcurrent happens, the cut-off time of the power tube is fixed so as to avoid the repeat starting of the power tube in short time and reduce power consumption; and two shifts of cut-off time are automatically selected according to the output voltage of the buck convertor so as to ensure the stability of the output voltage.

Method using square pulse excitation for high-impedance spectroscopy of anticorrosion coatings

Abstract: This paper presents a method of impedance spectroscopy designed for diagnostics of anticorrosion coatings on objects directly in the field. To shorten the time of impedance spectrum estimation (in the range from 1 mHz to 1 MHz) to a few minutes, harmonic signals were used to determine the spectrum above 10 Hz and a square pulse in the low-frequency range. To determine the impedance spectrum, digital signal processing algorithms adequate to the excitation signal were used. In the high-frequency range, discrete Fourier transform was used, but in the low-frequency range, continuous Fourier transformation was used, calculated in eight segments of acquisition which are dependent on pulse duration time. Experimental verification of the method was performed using four-element two-terminal RC network. The structure and component values of the test object represent the typical equivalent circuit of the anticorrosion coating in the early stage of undercoating rusting. The relative error of identification of component values does not exceed 2%-5%, depending on the placement of the component in the structure of the two-terminal network.

Temperature sensor circuit

Abstract: A temperature sensor circuit includes a band-gap reference voltage circuit. The resistor and diode-connected bipolar transistor of the band-gap reference voltage circuit are separated into a transistor-resistor series circuit and a transistor-diode series circuit. The transistor-resistor series circuit is configured such that an emitter of the bipolar transistor Q 21 is connected to a power supply voltage terminal V CC , a collector thereof is grounded via the resistor R 2 . The transistor-diode series circuit is configured such that an emitter of the bipolar transistor Q 20 is connected to the power supply voltage terminal V CC , a collector thereof is connected to a collector of the diode-connected bipolar transistor Q 19 , and an emitter of the diode-connected bipolar transistor is grounded. A voltage divider circuit 5 having a plurality of output terminals is connected to the transistor-resistor series circuit and the transistor-diode series circuit via first and second buffer circuits 3 and 4 , respectively.

A Rogowski coil current transducer designed for wide bandwidth current pulse measurement

Abstract: In this paper, high frequency behavior for a Rogowski coil is analyzed. Considering the coil frequency response model, a design method for this transducer is presented that the damping ratio based on termination resistor divides the coil frequency band into three bands: derivation band, proportion band and resonance band. Corresponding outside integrator circuits are built according with every band characteristic. A novel compound integration circuit is described in this paper which is consisted of self-integration, passive RC integration and active RC integration. This compound integrator improvements the measurement upper bandwidth limit of transducer above coil natural frequency. A coil of 100 wound number is constructed using compound integrator which is designed under 50Hz∼2.8MHz and sensitivity of 1mV/A. Simulation and experiment waveforms verify the transducer operates with both 50Hz grid current and 750A/us di/dt pulse current measurement.

Evaluating TLP transients and HBM waveforms

Abstract: Transmission Line Pulsing (TLP) is capable of determining a true impedance function in the s-domain, including time-dependent transients, as Z=Z 1 (1+as+bs2+…), with nonzero s-coefficients. We show how to determine the Z 1 and a terms and how to find more terms if desired, for long and short TLP pulses, drawing on network theory and approximation methods. We apply these to examples of inductive delay in devices. The same kind of methods are used to remove the effects of measurement tools themselves, including finite rise time of the TLP pulse and voltage droop of a current transformer. Then the true RC time constant of an HBM waveform is extracted as a network coefficient, through methods developed in this work.

RC Variability of Short-Range Interconnects

Abstract: Line edge roughness (LER) in end-of-the-roadmap integrated circuit interconnects causes variability in their resistance R, capacitance C and hence also their RC delay. We present an analysis of LER-induced variability of resistance, capacitance and delay of short-range interconnects within standard cells at the 32, 22 and 18 nm technology nodes using both a commercial RC extraction tool as well as a fast quasi-analytical (QA) method. Our QA method includes size dependent resistivity which, when coupled with LER, reveals increased resistance variability and total resistance in interconnects at these technology nodes. For example, the QA method predicts variability of 52% in resistance, 16% in capacitance and 36% in RC delay. When LER is the dominant source of variability there is a correlation of -0.8 between resistance and capacitance. Our results indicate interconnect variability is a significant and worsening problem, which should be included in statistical models of standard cells.

Traveling wave dielectrophoresis micropump based on the dispersion of a capacitive electrode layer

Abstract: A traveling wave dielectrophoresis microfluid pump based on structural dispersion is demonstrated. The phase shift between medium polarization and applied propagating field, necessary to generate asynchronous propagative forces in dielectrophoresis, is generated by an RC circuit consisting of the electrode insulator and the liquid conductivity. Since the device characteristics involve only bulk properties, the micropump does not require conductivity gradient or double layers, unlike existing micropumps using electro-osmosis and electrohydrodynamic shear forces. Its frequency of maximum pumping force can be made considerably lower than the dielectric relaxation frequency of the liquid. By decomposing the traveling wave electrode array into a rudimentary RC model, coincidence is found between optimized pumping conditions and crossover of the impedance measured between electrode combs. By using impedance spectroscopy alternately with pumping, the frequency of the applied signal can be matched in real-time to...

Electrostatic discharge protection circuit

Abstract: Disclosed herein are embodiments of electrostatic discharge (ESD) protection circuits. In certain embodiments an ESD protection circuit may include two series resistor-capacitor (RC) circuits. One series RC circuit may have a short time constant and may selectively activate a current shunt between two power rails in response to an ESD event. Accordingly, the ESD circuit may be able to respond to fast ramping ESD events. The other series RC circuit has a longer time constant, and maintains the current shunt in an active state for a sufficient amount of time to allow the ESD event to be completely discharged.

Simulation studies and modeling of Short Circuit current oscillations in IGBTs

Abstract: During Short-Circuit (SC) operations, strong current oscillations of IGBTs can appear. Simulation studies also confirm this. No parasitic inductances are required for such oscillations. A simplified equivalent circuit of the device, which is basically an RC oscillator, is able to reproduce the oscillations. The occurrence of oscillations depends on the model parameters, which can be related to the device structure and other conditions such as the gate resistance value, gate biasing, and DC-link voltage. This paper also shows that application of basic system theory methods to AC small-signal device simulation results (frequency-domain analysis under small-signal conditions) is appropriate to analyze the stability range of the IGBT under Short-Circuit.

Transient-to-Digital Converter for System-Level Electrostatic Discharge Protection in CMOS ICs

Abstract: A new on-chip RC-based transient detection circuit for system-level electrostatic discharge (ESD) protection is proposed, which can detect fast electrical transients during the system-level ESD test. A novel on-chip transient-to-digital converter composed of four RC-based transient detection circuits and four different RC filter networks has been successfully designed and verified in a 0.18- mum CMOS process with 3.3-V devices. The output digital thermometer codes of the proposed on-chip transient-to-digital converter correspond to different ESD voltages under system-level ESD tests. The proposed on-chip transient-to-digital converter can be further combined with firmware cooperation to provide an effective solution to solve the system-level ESD protection issue in microelectronic systems equipped with CMOS ICs.

Fluctuations of energy flux in a simple dissipative out-of-equilibrium system.

Abstract: We report the statistical properties of the fluctuations of the energy flux in an electronic RC circuit driven with a stochastic voltage. The fluctuations of the power injected in the circuit are measured as a function of the damping rate and the forcing parameters. We show that its distribution exhibits a cusp close to zero and two asymmetric exponential tails, with the asymmetry being driven by the mean dissipation. This simple experiment allows one to capture the qualitative features of the energy flux distribution observed in more complex dissipative systems. We also show that the large fluctuations of injected power averaged on a time lag do not verify the fluctuation theorem even for long averaging time. This is in contrast to the findings of previous experiments due to their small range of explored fluctuation amplitude. The injected power in a system of N components either correlated or not is also studied to mimic systems with large number of particles, such as in a dilute granular gas.

Bus driver circuit

Abstract: A bus driver circuit for driving a bus voltage is provided. The bus driver circuit comprises: a bus line output (CANL) the bus voltage of which is driven by the bus driver circuit; a first transistor (M1) having a gate, the voltage at the gate of the first transistor (M1) determining the bus voltage at the bus line output (CANL); a first capacitor (C1) connected to the gate of the first transistor (Ml) for driving the voltage at the gate of the first transistor (M1); a first switch (S1) connecting/disconnecting the first capacitor (C1) to a first voltage source (Vgm) via a first RC network comprising at least one resistor and at least one capacitor; and a second switch (S2) connecting/disconnecting the first capacitor (C1) to a predetermined fixed potential (GND 2) for discharging the first capacitor (C1) via a second RC network comprising at least one resistor and at least one capacitor. The first switch (S1) and the second switch (S2) are complementarily driven by a signal (TxD) on a data line.

Intelligent Switching Controller and Power Conversion Circuits and Methods

Abstract: In one embodiment, the present invention includes a circuit comprising a voltage estimation circuit to receive a first voltage and generate an estimation of an output voltage of a power conversion circuit based on the first voltage. The first voltage is from a circuit node between a first terminal of a switch and a first terminal of an inductor. The circuit further comprises a current estimation circuit to receive a first current and generate an estimation of an output current of the power conversion circuit based on the first current. The first current is a current through the switch. The circuit further comprises a pulse width modulation circuit to produce a pulse width modulated signal based on the estimation of an output voltage and the estimation of an output current.

High efficiency charging circuit and power supply system having such high efficiency charging circuit

Abstract: A charging circuit includes a main power circuit, a DC-to-DC converting circuit, a detection circuit and a controller. The main power circuit is electrically connected to a power source for converting an input voltage from the power source into a first voltage. The DC-to-DC converting circuit is electrically connected to the main power circuit for converting the first voltage into a second voltage to charge the energy storage element. The detection circuit is electrically connected to the main power circuit and the DC-to-DC converting circuit for detecting a terminal voltage of the energy storage element and the first voltage from the main power circuit, thereby generating a feedback signal. The controller is electrically connected to the detection circuit and the main power circuit for controlling operations of the first switching element in response to the feedback signal, so that the first voltage is adjustable according to the second voltage.

Multi-output power conversion circuit

Abstract: A multi-output power conversion circuit is provided for converting an input voltage into a standby voltage and a first output voltage. The multi-output power conversion circuit includes a transformer, a power switching circuit, a first rectifier-filter circuit, a second rectifier-filter circuit, a first switching circuit, a voltage-adjusting circuit, a feedback circuit and a power control circuit. The feedback circuit is connected to the first rectifier-filter circuit, the second rectifier-filter circuit and the system circuit. The feedback circuit generates a feedback voltage according to a power-status signal issued by the system circuit. The power control circuit is interconnected between the power switching circuit and the feedback circuit for controlling on/off statuses of the power switching circuit according to the feedback voltage. The feedback circuit generates the feedback voltage according to the power-status signal and selectively according to the first DC voltage or the second DC voltage.

Light-emitting diode lighting device, light fixture and light system

Abstract: PROBLEM TO BE SOLVED: To provide a light-emitting diode lighting device lighting an LED by a resonant-system circuit which detects the presence or absence of LED connection with a voltage generated in a resonance circuit in an appropriate range. SOLUTION: At the time of activation of an inverter circuit 3, an inverter control circuit 5 of a light-emitting diode lighting device 110 activates the inverter circuit 3 at an activation frequency at which a voltage outputted by a load circuit 4 (resonance circuit) is an on-voltage V f or higher at which a light-emission diode 7 is turned on and is equal to or lower than a predetermined voltage determined according to a withstand voltage of a component constituting the load circuit 4, and determines whether the inverter circuit 3 should be continuously driven based on a value of an adaptive signal corresponding to an LED current detected by a current detection circuit 3. COPYRIGHT: (C)2011,JPO&INPIT