Showing papers on "Negative impedance converter published in 1990"

Negative capacitance at metal-semiconductor interfaces

Abstract: A negative capacitance effect has been observed in metal‐semiconductor contacts. This phenomenon is explained by considering the loss of interface charge at occupied states below Fermi level due to impact ionization. A modified Shockley–Read treatment is proposed to interpret the experimental observations. In particular, a two‐energy‐level simplified model is presented to simulate the capacitance spectrum. The results are in good agreement with the experimental data.

Semiconductor memory operating with low supply voltage

Abstract: The present invention is intended to operate a semiconductor device at high speed with low voltage. A circuit configuration is used in which the transfer impedance between a common I/O line and a data line is changed depending on whether information is to be read or written. A current/voltage converter is provided which includes a MISFET different in conduction type to a select MISFET. Thus, the speed of reading information is increased. An intermediate voltage generator having high driving capability is provided. Thus, the circuit has sufficient driving capability for an LSI having large load capacitance. A voltage converter is provided which converts a data line supply voltage or word line supply voltage to a higher voltage. Therefore, stabilized signal transmission is ensured.

Internal voltage converter in a semiconductor integrated circuit

Abstract: An internal voltage converter of a semiconductor integrated circuit according to the invention comprises an oscillator 1, a sub-circuit 10 incorporating a buffer 2 and a charge-pumping circuit 3 and a supply portion 4, a main circuit 20 incorporating a buffer 2' and a charge-pumping circuit 3' and a supply portion 4', and a detector 5. A set of voltage converter stages are arranged in parallel in order to be divided in operation, so that futile power consumption is reduced in the case of the provision of the quiescent supply and the stability of the internal supply source voltage is also improved. Application to semiconductor memory devices.

A-d converter suitable for fuzzy controller

Abstract: In an A-D converter including a reference voltage generator, a D-A converter for outputting analog reference comparison voltage signals in response to digital signals; a comparator for comparing the voltages with an analog input voltage signal to be converted and outputting a reset signal when the voltage is substantially equal to the voltage, and a successive approximation register for successively outputting the digital signals to the D-A converter and an A-D converted signal in response to the reset signal, the D-A converter comprises in particular, at least one decoder block composed of plural array switches for coding any given function. Therefore, the analog input signal can be converted into the corresponding digital output signal in accordance with the coded function, thus providing an A-D converter suitable for use with a fuzzy controller. Further, the reference voltage generator is so configured as to easily change the coded membership function symmetrically or asymmetrically. A comparator priority decision logic circuit is further incorporated to allow input signals to be converted into output voltages in sequence in accordance with a multivalued membership function.

DC analysis and design of forward multi-resonant converter

Abstract: A DC analysis of the forward zero-voltage-switching multiresonant converter is presented. The voltage conversion ratio characteristics and semiconductor device voltage and current stresses are characterized. The results of the analysis are verified by experiments and SPICE simulation. It is found that to minimize the current and voltage stresses, the characteristic impedance must be maximized and the ratio of the primary to secondary resonant capacitances must be minimized. Based on the analysis, a procedure for designing the resonant tank with minimum current and voltage stresses is established. >

Bridgeless system for directly measuring complex impedance of an eddy current probe

Abstract: An all digital eddy current measurement system is described and illustrated in which an eddy current probe is driven by a driving signal and voltage signals representing the current through and voltage across the probe coil are used to calculate the magnitude and phase angle of a complex probe impedance. Digitization of the voltage signals is controlled by a control logic system which is run separately from but initiated by a microprocessor, the latter of which functions to analyze the acquired data and calculate impedance magnitude and phase angle values therefrom.

Analysis and design of LCL-type series resonant converter

Abstract: A series resonant power converter modified by adding an inductor in parallel with the transformer primary (or secondary) is presented. This configuration is referred to as 'LCL-type series resonant converter'. A simplified steady-state analysis using complex circuit analysis is presented. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 500 W converter are presented to verify the analysis. A narrow variation in switching frequency is required to regulate the output voltage constant for a very wide change in load, and the converter has load short circuit capability. It is shown that by placing the parallel inductor on the secondary-side, the parasitics of the high-frequency transformer can be used profitably. >

Fuel pump speed control by dc-dc converter

Abstract: A control apparatus for an electric fuel pump of a motor vehicle having an internal combustion engine which receives operating fuel from the motor operated fuel pump includes a dc-dc converter connected between a power source and the fuel pump. The dc-dc converter provides power for driving the fuel pump and is responsive to a voltage demand signal for setting the voltage level of the power. In one embodiment of the invention, a voltage demand signal generator, which generates the voltage demand signal, is a zener diode for generating a fixed voltage level for the power independent of the voltage level of the storage battery. In a second embodiment, the voltage demand signal generator is a portion of an engine control circuit for generating a varying voltage level for the power which is dependent on the operating conditions of the internal combustion engine.

Enhancement-mode zero-current switching converter

Abstract: An enhancement-mode converter module, which converts power from an input source for delivery to a load in a series of quantized energy transfer cycles, includes a zero-current switching converter, an enhancement-mode controller, an an input-output port for carrying synchronizing information to and from an external synchronizing bus. The enhancement mode controller adjusts the frequency at which energy transfer cycles are triggered in the zero-current switching converter to be the greater of a first frequency, which will regulate the load voltage to a setpoint voltage, Vsp, characteristic of the enhancement-mode controller, or a second frequency, which is indicated by an input delivered to the input-output port. In an array of such enhancement mode converter modules, wherein the outputs of all of the enhancement-mode converter modules are connected together to deliver power to a load, and wherein synchronizing information carried to a synchronizing bus by the input-output port of any of the converter modules is delivered as an input to the input-output ports of the balance of the converter modules by propagation along the synchronizing bus, all of the converter modules will synchronize to an operating frequency determined by the enhancement-mode controller having the highest setpoint voltage, and each of the converter modules will deliver an essentially constant fraction of the total power delivered to the load by the array.

Metallic channel unit network

Abstract: A channel unit network having a two-wire port for interconnecting a two-wire, bidirectional signal transmitting means with a four-wire digital transmitting means in a communication system to create a precision bidirectional simulated two-wire cable pair with an extended operation range over a transmission medium includes a signal processing circuit, tip and ring switch mode driver, a negative inductor circuit, a negative capacitor circuit, and a 200 Hz impedance circuit. The negative conductor circuit and the negative capacitor circuit are used to generate respective negative inductance and negative capacitance at 24 Hz in order to maintain loop stability. The 200 Hz impedance circuit is used to generate a positive impedance at a frequency of approximately 200 Hz so as to prevent overloading of external telephone communication testing circuitry.

A.c. to d.c. converter

Abstract: An a.c. to low voltage d.c. converter comprises a pair of input voltage supply lines (Vin, OV) and a semiconductor switch element (T1) and a capacitor (C1) connected in series between the supply lines. An output (Vo) for d.c. voltage is provided across the capacitor (C1). A sensing circuit (10) is responsive to the input voltage and is arranged to trigger the switching element (T1) to conduct only during a portion of the a.c. voltage below a predetermined voltage. Modified sensing circuits are described (Figs 2 to 4). The ac to dc converter may be formed as an integrated circuit (IC, Fig 5) and can be fed from an ac supply via a transformer (T) and a bridge rectifier (BR).

Low-power sense amplifier with feedback

Abstract: A sense amplifier is provided for sensing an impedance between two lines. The impedance has two levels. The two lines are, in one embodiment, a product term line and a product term ground line of a programmable logic device. In the amplifier, a pull-up circuit connects one of the two lines to a high voltage (for example, VDD =5 volts), and a pull-down circuit connects the other line to a low voltage (for example, ground). A negative feedback circuit controls the pull-up and pull-down circuits in response to the voltage on one of the two lines so that the impedance of the pull-up circuit changes in direct relationship with respect to the voltage of that line, and the impedance of the pull-down circuit changes in an inverse relationship with respect to that voltage. The feedback circuit has a delay at least as long as the transition of that voltage between its two values, which values correspond to the two impedance levels. The delay permits to increase the transition speed in a power-efficient manner. The delay can be implemented by simple circuitry. The pull-down circuit includes, in some embodiments, two electrical paths structured so as to make the amplifier more tolerant to temperature and process variations.

Parameter-free synthesis of zero-impedance converter

Abstract: A method of synthesizing a system which forces finite value of an impedance to zero comprising a positive current feedback of a prescribed functionalism and a negative voltage feedback to ensure stability of the system. The prescribed functionalism of the current loop uses arithmetic elements as well as voltage and current measurements to provide for a parameter-free synthesis of the converter whereby the converter operates in the measurement-based mode, the measured variables being the voltage and the current associated with the impedance of interest, without a need to supply values of both resistive and reactive components of the impedance of interest. The converter is used in synthesizing electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero-order dynamics and without specifying the resistive and the inductive values of the motor impedance.

Temperature compensation circuit for negative impedance driving apparatus

Abstract: A temperature compensation circuit used in a negative impedance driving apparatus such as an amplifier for driving a speaker as a load. A current flowing through the load is detected by a detection element connected to the load, and fed back therefrom, so that negative impedance driving is effected on the load. The detection element is set its temperature coefficient to be equal to or slightly larger than a temperature coefficient of the load, thereby the positive feedback gain is changed upon changing the temperature of the load so that negative impedance driving state is compensated. In another aspect of the invention, a temperature sensitive element or temperature detecting element for sensing or detecting the temperature of the detection element is arranged to change the positive feedback gain and compensate the negative impedance driving state.

Digital protective circuit breaker

Abstract: A circuit breaker includes a current detector for generator analog voltage signals in accordance with load current of respective phases and a control circuit for executing a tripping operation in response to the analog voltage signals. The control circuit includes an analog switch repeating a time division selecting operation that one of the analog phase voltage signals generated by the current detector is selectively allowed to pass through the same in a predetermined order, an analog-to-digital (A/D) converter for converting the analog voltage signal having passed through the analog switch to a corresponding digital signal, and a microcomputer receiving the digital voltage signal from the A/D converter and obtaining the effective load current value based on the digital voltage signals. The microcomputer generates a tripping order when the effective load current value exceeds a predetermined value. The control circuit may include an amplifier for amplifying low level analog voltage signals and supplying the amplified signals to the A/D converter.

Voltage follower circuit for use in power level control circuits

Abstract: A power control system includes a voltage follower circuit 17 which may be interposed between a load power control circuit 19 which adjusts the level of power applied to a load, and a variable impedance 10 whose internal impedance prescribes the desired level of power. A feedback voltage from the output of the voltage follower circuit is compared with a corresponding voltage across the variable impedance and the difference between them is used to drive the output voltage 27 of the voltage follower circuit toward the input voltage 11. The voltage follower circuit permits control by a single variable impedance of many more load power control circuits than a single variable impedance can normally handle, and without appreciably affecting the power level as a function of the impedance level. This circuit is particularly useful in a system for controlling the level of light received from fluorescent light fixtures controlled by electronic ballasts.

Method for judging life of lead storage battery

Abstract: PURPOSE: To judge life by measuring internal impedance by measuring the ripple voltage due to the ripple current contained in the charge current of the lead storage battery connected in a floating charge state through a rectifier. CONSTITUTION: In a system for the floating charge of a lead storage battery from a commercial power supply 1 through a rectifier 2, a ripple voltage detector 5 is inserted in the charge path of the lead storage battery 3 and the ripple voltage measured by the ripple voltage detector 5 and the voltage measured by an internal impedance measuring device 6 are inputted to an adder 7 to calculate added voltage and the value calculated by dividing this added voltage by the measured current flowing when the measured voltage of the internal impedance measuring device 6 is applied is displayed as an internal impedance. By this method, the internal impedance in a floating charge state can be accurately measured. COPYRIGHT: (C)1991,JPO&Japio

Current-free synthesis of parameter-free zero-impedance converter

Abstract: A method of synthesizing a system which forces finite value of an impedance to zero comprising a positive voltage feedback of a prescribed amount of voltage feed back and a negative voltage feedback to ensure stability of the system, whereby no current through the impedance is sensed and no parameters of the impedance are required to be known implying minimization of measurement noise and adaptive/self-tuning operation, respectively, in applications in which the method is used to synthesize load independent switch mode power converters and electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero order dynamics.

Biasing networks for balanced mixers

Abstract: A balanced mixer, including at least one pair of switching type diodes and at least one impedance transformer, such as balun or RF transformer, for coupling at least one of a radio frequency (RF) or local oscillator (LO) signal to the diodes in a balance impedance configuration, also includes a voltage source biasing network for supplying a bias voltage to the mixing diodes through a relatively low source impedance. The bias voltage network comprises a voltage divider including relatively high value resistor and a relatively low value resistor connected in series between a source of supply voltage and ground though a winding of the impedance transformer. The bias voltage biases the mixing diodes slightly below the threshold of conduction so that the performance of the mixer can be optimized over a relatively wide LO signal amplitude range and so that the power requirements of the LO can be reduced. The low source impedance of the voltage source inhibits variations of the bias voltage due to the rectification of the LO signal but is isolated from ground for RF and LO signals because the connection to ground is through the winding of the impedance transformer.

Ultrasonic generator with a piezoelectric converter

Abstract: In an ultrasonic generator the driver circuit of a piezoelectric converter is provided with a switching regulator under control of a microcomputer, the pulse duty factor and frequency of the switching regulator being controlled in response to the converter's impedance which is detected by means of a measuring circuit.

Positive to negative voltage translator circuit and method of operation

Abstract: There is disclosed a circuit and method for converting on/off logic signals from one medium to on/off signals useful in a different medium. The circuit is particularly adapted to translate from positive voltage levels to negative voltage levels. The circuit includes voltage control levels for precisely controlling voltage as a function of temperature, all while only using positive voltage levels on the conversion circuit.

Voltage converter with self-integration and voltage summation

Abstract: An electronic device which, fed from a sinusoidal or randomly variable network, makes it possible to supply the input of a converter with which it is equipped with a DC voltage, a load connected at the output also being fed with a DC voltage envelope, whereas the power factor of the current taken from the mains is kept at unitary value and said current is the image of the voltage which produces it. The high frequency output circuit of the converter loads the series circuit formed by the load 13 associated with an impedance 16. The voltage developed across the terminals of the impedance 16 is rectified by a rectifier bridge 15 mounted in series with a mains rectifier bridge 10 so that these voltages, added to the input of the converter 12, affect the envelope of a DC voltage, this also resulting in supplying a DC voltage envelope to receiver the load 13. The current taken from the mains has a unitary power factor and is proportional to the input voltage. This device is applicable to the majority of electronic converters used as ballasts, transformers, stabilized power supplies, and so on.

Current-free synthesis of improved parameter-free zero-impedance converter

Abstract: A method of synchesizing a system which effectively forces finite value of an impedance to zero comprising a most inner positive voltage feedback loop and an inner negative voltage feedback loop and an outer negative voltage feedback loop, whereby a voltage difference between the most inner positive feedback loop and the inner negative feedback loop is fed back to compensate for the voltage drop across the impedance of interest in both steady state and transient and whereby no current through the impedance is sensed and no parameters of the impedance including parameters of the plant under the control are required to be known implying minimization of measurement noise and adaptive/self-tuning operation, respectively, in applications in which the method is used to synthesize load independent switch mode power converters and electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero order dynamics.

Zero-voltage-switched multiresonant converter for high-power, pulse-load applications

Abstract: A full-bridge zero-voltage-switched (ZVS) multiresonant converter (MRC) was built for a pulse load with a peak power of 1.44 kW and an average power of 360 W. The converter works with an input-voltage range from 220 to 350 V, and delivers 32 V to the pulse load with a constant peak current of 45 A. The efficiency range of the converter was measured from 82.5 to 90.5%. The maximum efficiency occurs at low line and decreases as the input voltage increases. Detailed analysis and design of the converter, along with experimental results, are presented. >

A full-bridge zero-voltage-switched multi-resonant converter for pulse-load applications

Abstract: The zero-voltage-switching multiresonant technique was used to fabricate a full-bridge converter for high-power, pulse-load applications. The complex operation of the full-bridge zero-voltage switched multiresonant converter is analyzed. The converter can operate in four modes, each representing a specific topological sequence. The DC voltage conversion-ratio characteristics encompassing all possible operating modes are derived. These characteristics are used to define a complete, step-by-step design procedure which minimizes the conduction loss in the primary side of the power stage by minimizing the RMS currents through the switches. The design procedure was used to fabricate a converter that operates at an input voltage of from 220 to 350 V and delivers 32 V to pulse load, with a peak current of 45 A. The maximum efficiency of the converter was measured at 90.5%. >

Current limiting arrangement in a power converter

Abstract: A power converter unit includes a pair of switching DC/DC converter secti for positive and negative voltages which incorporate a MOSFET switching arrangement in which a pair of MOSFETs are forced to share the output load current equally, a current limiting arrangement which activates shutdown whenever the current threshold limit is exceeded, and an internal grounding arrangement which minimizes output of current spikes by isolating the switching spikes from the input and output. The current limiting arrangement includes a resistor for sensing the voltage between the input and output of the converter and a comparator for comparing the sensed voltage with a reference threshold voltage and being operable to shut down the converter when the sensed voltage exceeds the reference threshold voltage.

An approximate steady state and small signal analysis of the parallel resonant converter running above resonance

Abstract: A half bridge parallel resonant converter (PRC) running above resonance in the constant output voltage mode is analysed. The steady state analysis the small signal analysis, and the regulation of the power converter are reviewed. An approximated steady state analysis for the constant output voltage mode is reviewed. This analysis is based on an AC equivalent circuit using the fundamental wave of the rectangular input voltage of the resonant tank. Although approximated, the AC equivalent circuit provides physical insight into the behaviour of the PRC since the higher order harmonics of the resonant voltage across the resonant converter are negligible, if the converter operates above resonance. After steady state analysis, design considerations for the PRC running above resonances are given.

Power supply device with unbalance monitoring circuit

Abstract: A power supply device with a monitoring circuit for detecting an unbalance in a direct voltage transmitted between two line conductors and which is normally balanced with respect to ground potential. A voltage divider circuit is arranged between the two line conductors and consists of components which are identical in pairs. The center tap of the voltage divider is connected to ground potential and at further taps thereof in each case positive and negative part-voltages are produced. A first positive part voltage is compared with a second negative part voltage and a second positive part voltage is compared with a first negative part-voltage so that the balance of the direct voltage with respect to ground potential is simply and reliably monitored.

Induction motor performance when fed from single to three phase converters

Abstract: The most popular single-to-three-phase converter consists of a capacitor connected between the motor's third phase and either the live or neutral of the single-phase supply. Proper voltage balance at any one given operating point is obtainable with the autotransformer-capacitor converter (ACC), while proper balance over the entire operating range is obtainable with a variable-inductor-variable-capacitor converter (LCC). The appropriate vector diagrams of the above-mentioned converters are developed to provide insight into their operation. An assessment of the derating necessary in the presence of unbalanced voltages and currents is presented. A technique for the measurement of the negative sequence voltage is discussed. Measured results for the case when an induction machine starts directly off a three-phase supply and off the above converters are included. >

Circuit arrangement for simulating a variable impedance, particularly an ohmic resistance

Abstract: A circuit arrangement for simulating a variable impedance is specified which exhibits a current/voltage converter (1), the output of which is connected to a voltage proportional element (7). The output (9) of the voltage proportional element (7) is fed back to a second input (3) of the current/voltage converter (1) in such a manner that the output voltage (UE) is adjusted in such a manner that it corresponds to the load voltage (UL). The value of the simulated resistance (R) can be varied by varying the proportionality factor of the voltage proportional element (7).