Showing papers on "Voltage multiplier published in 2000"

A new charge pump without degradation in threshold voltage due to body effect [memory applications]

Abstract: A new charge-pump circuit with the controllable body voltage is proposed. By adjusting the body voltage, the back bias effect is removed and the threshold voltage of the MOSFET used as a switch is kept constant. With no threshold voltage increase, higher output voltage than the conventional charge pump can be obtained in the proposed charge pump. With two auxiliary MOSFETs used to update the body voltage, the proposed charge pump shows compatible performance of the ideal diode charge pump.

Circuit providing a control voltage to a switch and including a capacitor

Abstract: A circuit for providing a control voltage to a switch includes a capacitor, a first pair of switches for coupling the capacitor to an input voltage source and a second pair of switches for coupling the capacitor to the switch. The first pair of switches is controlled by a control signal in response to the voltage across the capacitor in order to prevent overcharging the capacitor beyond a first predetermined level. The second pair of switches is controlled by a second control signal in response to the voltage across the switch in order to replenish the capacitor voltage when the capacitor voltage falls to a second predetermined level. The first and second pairs of switches are closed during non-overlapping time intervals in order to isolate the switch from the input voltage source, thereby preventing switching transients from affecting the input voltage source and permitting the circuit to be used to drive a variety of switch types arranged in a variety of configurations.

An on-chip voltage regulator using switched decoupling capacitors

Abstract: On-chip decoupling capacitors are actively switched to suppress resonance in the power distribution system of a microprocessor. With this scheme, charge storage capacity is amplified, while instantaneous monitoring of rail activity and dynamic control of the switching response provide bandlimited on-chip voltage regulation.

Series resonant ZCS-PFM DC-DC converter with multistage rectified voltage multiplier and dual-mode PFM control scheme for medical-use high-voltage X-ray power generator

Abstract: In general, high-voltage DC power supplies employing a variety of high-frequency inverters are implemented for constant value control schemes. In particular, their good transient and steady state performances cannot be achieved under wide load variations for a medical-use high-voltage X-ray generator, ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1250 mA, respectively. A high-voltage DC power supply designed for X-ray power generator applications is considered, which uses a series resonant inverter-linked multistage DC voltage multiplier instead of a conventional high-voltage diode module rectifier connected to the secondary side of a high-voltage transformer. A constant on-time/variable frequency control scheme of this converter operating at zero-current soft switching mode is described. Introducing the capacitor-diode cascaded multistage voltage multiplier, the secondary turn numbers and secondary-side stray capacitance of the high-voltage, high-frequency transformer, as well as the rectifier diode voltage ratings, can be greatly reduced. It is shown that the proposed converter control scheme of the two-step selective changed frequency selection switching is more effective for improving the output voltage responses. The series resonant high frequency transformer-linked voltage-multiplying rectifier is evaluated for an X-ray high-voltage generator on the basis of simulation analysis and observed data in experiment.

Four-quadrant CMOS current-mode multiplier independent of device parameters

Abstract: In this work, we present a four-quadrant CMOS current-mode multiplier based on the square-law characteristics of an MOS transistor operated in the saturation region. One advantage of this multiplier is that the output current is independent of MOS transistor device parameters; another, that the input resistance is independent of the input current. Simulations of the multiplier demonstrate a linearity error of 1.22%, a THD of 1.54%, a -3 dB bandwidth of 22.4 MHz, and a maximum power consumption of 0.93 mW. Operation of the multiplier was also confirmed through an experiment using CMOS 4007 IC's.

Efficient CMOS DC-DC converters based on switched capacitor power supplies with inductive current limiters

Abstract: A novel class of DC to DC power converters and a method of conversion is provided using high-frequency switched capacitors where the switches are implemented by CMOS transistors or diodes on an integrated-circuit chip and using inductors to limit charging current. High efficiency is achieved using inductors to reduce energy losses in circuit capacitors by high frequency switching when inductor current is zero and capacitor voltage is maximized. The high-frequency (100 MHz or greater) operation of the converter circuit permits the use of inductors with a low inductance value on the order of 100 nH (100×10 −9 Henrys) capable of fabrication directly on an integrated-circuit (IC) chip. The use of CMOS integrated components allows the entire converter to be formed on a single IC chip, saving significant space within the portable system. Output voltage and current is high enough to permit EEPROM programming. In addition, fluctuations in the output voltage (ripple voltage) are substantially eliminated when several of the converter circuits are used in parallel.

Ultra-capacitor based dynamically regulated charge pump power converter

Abstract: A charge pump power converter efficiently provides electrical power by dynamically controlling a switch matrix of the charge pump that includes a flying ultra-capacitor C U F . Instead of open-loop oscillator-based control, a dynamic controller provides power upon demand by sensing the output voltage and changing the operating frequency of the charge pump in response. Moreover, this closed-loop dynamic control intrinsically voltage regulates the output voltage of the charge pump power converter without the inefficient addition of a step-down voltage regulator, downstream of the power converter. In addition, this closed-loop dynamic control allows for maintaining a desired output voltage even with variations in the input voltage. Further efficiency is achieved by controlling the charging and discharging of the flying ultra-capacitor C U F , both in rate of current change and in voltage ripple.

Charging device and charging method thereof

Abstract: The present invention relates to a charging device for storing electric energy in a plurality of electrical double layer capacitors, comprising a power source circuit, a capacitor bank having a plurality of capacitors, a control circuit for switching an interconnection state of the plurality of capacitors, and a voltage monitor circuit for monitoring a charged voltage in the plurality of capacitors, which repetitively carries out a step of performing a charging operation by switching the plurality of capacitors in the capacitor bank to a serial connection state, and a step of monitoring a charged voltage by using a voltage monitor circuit by switching the plurality of capacitors to a parallel connection state until the charged voltage reaches a predetermined value. By connecting the plurality of capacitors in series when charging the same, the power source circuit can be downsized as the charging current is reduced, and by connecting the same in parallel when monitoring the voltage, each capacitor can be charged equally as a voltage in each capacitor is leveled. Further, because the voltage monitor circuit can be a single circuit, not only can the size and cost of the charging device be reduced significantly, but also a heat quantity generated from the voltage monitor circuit can be suppressed markedly, thereby making it possible to

A 1 V CMOS switched-opamp switched-capacitor pseudo-2-path filter

Abstract: Switched-opamp (SO) techniques are explored to operate switched capacitor (SC) circuits in 1 V supply without on-chip voltage multiplier or low V/sub T/ devices. However, the existing SO techniques require isolating the opamp from the signal path by turning off completely either the entire opamp or its output stages after the integration phase. As a result, these SO techniques cannot be applied to realize the useful SC pseudo-N-path filters, which require an idle phase in the system for further signal processing. A modified SO technique implements an additional switchable opamp in parallel with the original switchable opamp but working in an alternative clock phase. As such, for every clock phase, there exists an opamp that is fully functional in the SC system. With the two switchable opamps both realized in a two-stage approach, it is sufficient to turn off only the output stages to isolate the signal path. The two switchable opamps are further combined to realize a single two-switchable-output-pair opamp to save power and area and to minimize the mismatch. To demonstrate the idea, a 1 V fully differential two-switchable-output-pair opamp is realized in a 0.5 /spl mu/m CMOS process with nMOS and nMOS threshold voltages 0.66 V and /spl sim/0.85 V respectively.

Voltage control circuitry for charging output capacitor

Abstract: Battery driven voltage control circuitry charges an output capacitor, which periodically supplies a current pulse. The circuitry converts battery voltage VBAT to a charging voltage VUPC based upon programmed parameters and the voltage VCOMPL at the capacitor. The circuitry includes a voltage converter for multiplying VBAT to produce VUPC. VCOMPL is sampled to determine its “droop” at the end of an output current pulse. If the droop is lower than a threshold, then the voltage converter increases the charging voltage. If the droop is above a threshold, then the voltage converter reduces the charging voltage. This feedback maintains the output voltage within an acceptable operating range to produce an efficacious output current pulse for stimulation without causing unproductive energy loss. In order to avoid premature depletion of battery energy, VUPC is compared with VCOMPL to determine the optimum clock rate to be used to convert VBAT to VUPC.

High efficiency electronic circuit for generating and regulating a supply voltage

Abstract: A high-efficiency electronic circuit generates and regulates a supply voltage and includes a charge-pump voltage multiplier which is associated with an oscillator and has an output connected to a voltage regulator in order to ultimately output said supply voltage Advantageously, the circuit comprises a first hysteresis comparator having as inputs the regulator output and the multiplier output, and comprises a second hysteresis comparator having as inputs a reference potential and a partition of the voltage presented on the regulator output The comparators are structurally and functionally independent of each other, and their outputs are coupled to the oscillator through a logic circuit to modulate the oscillator operation

Series resonant high-voltage ZCS-PFM DC-DC converter for medical power electronics

Abstract: In general, high-voltage DC power supplies employing a variety of high-frequency inverters are implemented for constant value control schemes. In particular, their good transient and steady-state performances cannot be achieved under wide load variations involved in a medical-use X ray tube drive high voltage generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1250 mA, respectively. A high-voltage power supply designed for X ray power generator applications is considered, which uses series resonant inverter-linked multistage DC voltage multiplier instead of a conventional high voltage diode module rectifier connected to the second-side of a high-voltage transformer, a constant on-time/variable frequency control scheme of this converter operating at zero-current switching modes is described. Introducing the capacitor-diode based multistage voltage multiplier, the secondary turn numbers and stray capacitance of the high-voltage high-frequency transformer as well as the rectifier diode voltage ratings can be greatly reduced. It is proven that the proposed converter control scheme of the 2 step frequency selected switching is more effective for improving output voltage responses. A series resonant high-frequency transformer-linked voltage-multiplying rectifier is evaluated for any ray high-voltage generator on the basis of simulation analysis and observed data in experiment.

Voltage multiplier having an intermediate tap

Abstract: A power supply circuit for use in a LCD device includes a voltage multiplier which outputs a multiplied voltage VLCD 1 and a median voltage VLCD 2 . A plurality of voltage followers are grouped in two groups each operating on the multiplied voltage VLCD 1 or the median voltage VLCD 2 , thereby reducing power dissipation of the LCD device.

DC/DC converter and method of operating a DC/DC converter

Abstract: The invention relates to a DC/DC converter including a charge pump circuit comprising one or more capacitors and a plurality of controllable switches connected thereto, the controllable switches being controllable by a control circuit so that the capacitor(s) is/are alternatingly switched in a charging and discharge phase; a first current source set to a predetermined base current located either in the discharge or charging path of the charge pump circuit and a second current source connected in parallel thereto; and a regulator circuit for generating a first control signal representing the difference between a voltage characterizing the output voltage and a first reference voltage and controlling the second current source when the charge pump circuit is active so that the controllable current is reduced or increased with an increase and reduction respectively in the difference to track the voltage characterizing the output voltage in accordance with the first reference voltage; and for generating a second control signal guided to the control circuit, this signal assuming a first status when the voltage characterizing the output voltage exceeds a second reference voltage at a predetermined level above the first reference voltage, upon which the control circuit deactivates the charge pump circuit, and assumes a second status when the voltage characterizing the output voltage drops below the second reference voltage, upon which the control circuit activates the charge pump circuit. The invention relates further to a method of operating a DC/DC converter.

Nonlinear stepped programming voltage

Abstract: A voltage control circuit that narrows the distribution of threshold voltages of memory cells by using nonlinearly incremented programming voltages. To do so, the voltage control circuit applies to the memory cells a first program pulse of a first voltage, a second program pulse of a second voltage to the memory cell, and a third program pulse of a third voltage, where the difference between the third voltage and the second voltage is less than the difference between the second voltage and the first voltage.

Voltage controlled oscillator with automatic center frequency calibration

Abstract: A voltage controlled oscillator with automatic center frequency calibration. The frequency range of the oscillator is increased by switchable capacitor circuits which add or remove extra capacitors in parallel with the variable capacitor of the resonant circuit. Different voltage versus frequency characteristics are obtained. The switchable capacitor circuits are controlled by a detection circuit that sends a reset pulse to a feedback circuit of the VCO when a control voltage from the feedback circuit reaches predetermined low or high voltage limits of the characteristics. Upon reception of the reset pulse, the feedback circuit changes the control voltage from the reached limit into an intermediate voltage between the low and high voltage limits. The control voltage is reset in the middle of a voltage versus frequency characteristic onto which the output frequency is also centered. The VCO includes a selection circuit adapted to immediately change the value of the control voltage.

Highly-Efficient Low-Voltage-Operation Charge Pump Circuits Using Bootstrapped Gate Transfer Switches

Abstract: This paper describes highly efficient on-chip high-voltage multipliers using charge pump circuits. The proposed charge pump circuits use bootstrapped gate transfer switches to avoid the threshold voltage drop in conventional Dickson charge pump circuits and enables them to generate a given voltage with a smaller number of pumping stages, which results in higher efficiency. The SPICE simulation results show that the proposed circuits have high pumping gain, are suitable for low-voltage operation, and have ample current drive capability.

Dynamically-switched power converter

Abstract: A DC/DC power converter is efficiently switched to produce a predetermined output voltage across a load capacitor as required by a load device. In particular, a capacitive and/or inductive element is switched between a charge and discharge state as required to maintain the output voltage. For a capacitive-only power converter, or charge pump, comparison of the output voltage to a reference voltage efficiently switches a fly capacitor between charging and discharging states. Also, power converter based on switching of an inductive element with a synchronous rectifier and switch to charge the load capacitor is made more efficient by a hysteretic comparison of the output voltage to predetermined thresholds for stopping the Pulse Width Modulation (PWM) modulation when the predetermined output voltage is achieved. The power converters illustrated are suitable for integrated circuit implementation and may be combined with other elements of a battery to produce a more efficient battery, achieving longer service life and output voltage stability.

Series resonant high-voltage PFM DC-DC converter with voltage multiplier based a two-step frequency switching control for medical-use X ray power generator

Abstract: In general, high-voltage DC power supplies employing a variety of high-frequency inverters are implemented for constant value control schemes. In particular, their good transient and steady-state performances can not be achieved under wide load variations for a medical-use high voltage X ray generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1250 mA, respectively. A high-voltage DC power supply designed for X ray power generator applications is considered, which uses series resonant inverter-linked multistage DC voltage multiplier instead of conventional high voltage diode module rectifier connected to the secondary-side of a high-voltage transformer. A constant on-time/variable frequency control scheme of this converter operating at zero-current soft switching mode is described. Introducing the capacitor-diode cascaded multistage voltage multiplier, the secondary turn numbers, and secondary-side stray capacitance of the high-voltage high-frequency transformer as well as the rectifier diode voltage ratings can be greatly reduced. It is proven that the proposed converter control scheme of the 2 step changed frequency selection switching is more effective for improving output voltage responses. A series resonant high-frequency transformer-linked voltage-multiplying rectifier is evaluated for an X ray high voltage generator on the basis of simulation analysis and observed data in experiment.

Dividing, isolating, and rectifying circuit and standby power source

Abstract: First, second and third capacitors ( 11, 12, 13 ) having predetermined capacitance values are connected in series in a commercial alternating current line. A rectifier bridge ( 14, 15, 16, 17 ) including two diodes ( 14, 15 ) having backward characteristics adjusted to a Zener voltage is connected in parallel with the capacitor ( 12 ) in the center, and a smoothing capacitor is connected between a first end and a second end of the rectifier bridge ( 14, 15, 16, 17 ). As a result, it is possible to divide alternating current (AC) from a power input terminal into a desired voltage while insulating it, and clip it with a predetermined voltage to shape it into a voltage waveform close to a rectangular wave and smooth it. Thereby, a stabilized DC voltage with less ripples can be obtained.

Analog to digital voltage measuring device

Abstract: A voltage measuring circuit for measuring a voltage level of an unknown voltage source, including a capacitor configured for storing a charge from the unknown voltage source, a switch such as a transistor, configured to discharge the capacitor after the capacitor has reached a known threshold voltage, a microprocessor which controls the switch and measures the amount of time required to charge the capacitor to the threshold voltage, allowing the voltage level to be measured without disconnecting the capacitor from the circuit.

Charging device for a cellular phone

Abstract: A charging device for a cellular phone includes a first housing having a first receiving space provided with a plurality of terminals on an inner side wall thereof. One outer side wall of the first housing is connected pivotally to an outer side wall of a second housing. The second housing has a second receiving space in the same direction as the first receiving space. The inner wall of the second receiving space is provided with two conductors. A voltage multiplier circuit and a voltage stabilizing and rectifying circuit are disposed between the first and second housings. In use, a rechargeable battery of the cellular phone is disposed in the first receiving space, whereas conventional batteries are disposed in the second receiving space to permit charging of the rechargeable battery via the circuits. The charging device is convenient to use and does not occupy a lot of space.

High voltage CMOS switch

Abstract: A high voltage CMOS switch circuit having an arrangement of device connections such that the individual transistor devices are substantially the same size, improving performance while reducing size and providing breakdown protection. The circuit switches a high voltage to the output based on a low voltage input. The circuit is ratio-less and self-biased, capable of operating a very low supply voltage compared to the state of the art.

Implantable cardiac stimulating device with optimized demand

Abstract: It is important in cardiac pacing devices and systems to achieve efficient power utilization and conservation to extend the life of the battery cells, thereby extending the intervals between invasive medical procedures to replace components in the cardiac pacing system. A device and method are provided. The cardiac pacing device comprises a battery, a discrete time switched capacitor pacing power supply comprising a charge transfer capacitor bank comprising at least two capacitors, and a pace output supply capacitor which can discharge current to the tissue of a patient. A pacing supply design has a multiplicity of battery voltage multiplication factors and operating frequency settings. The pacing supply, voltage multiplier settings and operating frequency are automatically adjusted to compensate for changing pace output settings, load, cardiac cycle rate, and/or battery condition. The pacing supply voltage multiplier setting and frequency are varied over the useful life of the battery so that on average, from a beginning of life period for the battery to an end of life period for the battery, the voltage multiplier and the switching frequency increase. In the pacing device, the voltage multiplier and the switching frequency rate is determined by a reading of the rate of charging or charge time of a storage capacitor with said pacing device.

A novel one-stage forward-type power-factor-correction circuit

Abstract: A novel power-factor-correction (PFC) circuit is proposed which is constructed with one stage by using a single forward converter. This PFC circuit has functions of high power factor and suppression of the output voltage ripple. The high power factor is accomplished by making the PFC circuit operate in the discontinuous conduction mode and the suppression of the output voltage ripple by using the exciting energy of the transformer in the forward converter.

Apparatus and method for compensating gamma voltage of liquid crystal display

Abstract: A gamma voltage compensating apparatus and method for a liquid crystal display wherein a gamma voltage is compensated to improve a charge characteristic of a pixel. In the apparatus, a pre-charge voltage generator generates a pre-charge voltage allowing a gamma voltage to be higher than a target voltage in a certain time interval every one horizontal period. A gamma voltage generator adds the pre-charge voltage from the pre-charge voltage generating means to a predetermined reference voltage in such a manner to have a different level in accordance with a voltage level of an image signal, thereby generating a gamma voltage. Accordingly, a gamma voltage including a pre-charge voltage higher than the target gamma voltage is applied to improve a charge characteristic of the pixel, thereby preventing a charged voltage difference from being generated between the horizontal and vertical pixels.

Very low-voltage class AB CMOS precision voltage and current rectifiers

Abstract: Simple class-AB CMOS voltage and current precision rectifier circuits that operate from a single supply close to a transistor's threshold voltage are introduced. The current rectifier has output voltage swings comparable to the supply voltage and the voltage rectifier has wide input and output swings. Simulations of both rectifiers operating at 20 MHz are shown. Experimental results of a test chip are presented that verify the proposed circuits. A full wave precision rectifier based on the proposed rectifier cells is discussed.

AC voltage regulator

Abstract: An AC voltage regulator, which not only has a fast response speed with respect to input voltage fluctuations but also is small in size and light in weight and is capable to boost an input voltage, comprises a high-frequency transformer 4, a first bi-directional semiconductor switch circuit 3, a second bi-directional semiconductor switch circuit 5 and a third bi-directional semiconductor switch circuit 6; an input AC voltage is ring-modulated by the first bi-directional semiconductor switch circuit 3 and the obtained ring-modulated voltage is transformed at a high frequency by the high-frequency transformer 4 and then demodulated by the second bi-directional semiconductor switch circuit 5, and the obtained AC demodulated voltage is added to the input AC voltage to produce an AC raised voltage, and the AC raised voltage is pulse width modulated by the third bi-directional semiconductor switch circuit 6, which is controlled to become ON only while the second bi-directional semiconductor switch circuit 5 is OFF, and the AC raised voltage is continuously regulated by continuous regulation of a duty ratio D of the second bi-directional semiconductor switch circuit 6 in the pulse width modulation.

A novel three-phase multilevel voltage source converter

Abstract: During the past few years, the multilevel converter has drawn tremendous interests for power electronic applications. Many topologies have been introduced, such as the diode-clamp multi-level converter, flying-capacitors multilevel converter and others. These topologies produce a staircase voltage waveform from several levels of DC or capacitor voltage source which causes a few problems such as capacitor voltage balance and numerous sums of devices. This paper proposes a novel three-phase multi-level voltage source converter with more levels and less devices and without the problem of capacitor voltage balance.