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Showing papers on "Rise time published in 1997"


Journal ArticleDOI
Toru Tanzawa1, T. Tanaka
TL;DR: In this paper, the authors have analyzed the Dickson charge pump circuit and derived the optimum number of stages to minimize the rise time of the output voltage and power consumption during boosting.
Abstract: Dynamics of the Dickson charge pump circuit are analyzed. The analytical results enable the estimation of the rise time of the output voltage and that of the power consumption during boosting. By using this analysis, the optimum number of stages to minimize the rise time has been estimated as 1.4 N/sub min/, where N/sub min/ is the minimum value of the number of stages necessary for a given parameter set of supply voltage, threshold voltage of transfer diodes, and boosted voltage. Moreover, the self-load capacitance of the charge pump, which should be charged up at the same time as the output load capacitance of the charge pump, has been estimated as about one-third of the total charge pump capacitance. As a result, the equivalent circuit of the charge pump has been modified. The analytical results are in good agreement with simulation by the iteration method, typically within 10% for the rise time and within 2% for the power consumption. In the case of a charge pump with MOS transfer transistors, the analytical results of the rise time agree with the SPICE simulation within 10%.

343 citations


Journal ArticleDOI
TL;DR: In this paper, negative input shaping is used to reduce residual vibration in computer controlled machines by convolving a sequence of impulses with a desired system command and the resulting shaped input is then used to drive the system.
Abstract: Input shaping reduces residual vibration in computer controlled machines by convolving a sequence of impulses with a desired system command The resulting shaped input is then used to drive the system The impulse sequence has traditionally contained only positively valued impulses However, when the impulses are allowed to have negative amplitudes, the rise time can be improved Unfortunately, excitation of unmodeled high modes and overcurrenting of the actuators may accompany the improved rise time Solutions to the problem of high-mode excitation and overcurrenting are presented Furthermore, a simple look-up method is presented that facilitates the design of negative input shapers The performance of negative shapers is evaluated experimentally on two systems; one driven by a piezo actuator and the other equipped with DC motors

240 citations


Journal ArticleDOI
TL;DR: In this article, the failure of magnet wires under repetitive pulses is attributed to a single factor but is a result of the combined effects of partial discharge, dielectric heating, and space charge formation.
Abstract: The failure of magnet wires under repetitive pulses as seen in inverter-fed motors cannot be attributed to a single factor but is a result of the combined effects of partial discharge, dielectric heating, and space charge formation. Voltage overshoots produced by PWM drives may be above discharge inception voltage. Partial discharge may therefore be present in inverter-fed motors. In addition to partial discharge, pulses with a fast rise time and high frequency enable the insulation to generate local dielectric heating, which increases the local temperature. The degradation rate of the insulation is therefore increased. Furthermore, the fast rise and fall of pulses make it possible for space charges to accumulate in the winding insulation and on its surface.

222 citations


Journal ArticleDOI
TL;DR: Processing data from the dynamic characterisation of the sensor array, considerably improves its identification performance, rising the discrimination success rate from a 66% when only steady-state signals are used up to 100%.
Abstract: Quantitative analysis of gases, by means of semiconductor sensor arrays and pattern-recognition techniques such as artificial neural networks, has been the goal of a great deal of work over the last few years. However, the lack of selectivity, repeatability and drifts of the sensors, have limited the applications of these systems to qualitative or semi-quantitative gas analysis. While the steady-state response of the sensors is usually the signal to be processed in such analysis systems, our method consists of processing both, transient and steady-state information. The sensor transient behaviour is characterised through the measure of its conductance rise time (Tr), when there is a step change in the gas concentration. Tr is characteristic of each gas/sensor pair, concentration-independent and shows higher repeatability than the steady state measurements. An array of four thick-film tin oxide gas sensors and pattern-recognition techniques are used to discriminate and quantify among ethanol, toluene and o-xylene [concentration range: 25, 50 and 100 ppm]. A principal component analysis is carried out to show qualitatively that selectivity improves when the sensor behaviour is dynamically characterised. The steady-state and transient conductance of the array components are processed with artificial neural networks. In a first stage, a feed-forward back-propagation-trained ANN discriminates among the studied compounds. Afterwards, three separate ANN (one for each vapour) are used to quantify the previously identified compound. Processing data from the dynamic characterisation of the sensor array, considerably improves its identification performance, rising the discrimination success rate from a 66% when only steady-state signals are used up to 100%.

174 citations


Proceedings ArticleDOI
01 Nov 1997
TL;DR: A general methodology to analyze crosstalk to obtain insight into effects that are likely to cause errors in deep submicron high speed circuits and shows that crosStalk effects can be significantly aggravated by variations in the fabrication process.
Abstract: In this paper we develop a general methodology to analyze crosstalk to obtain insight into effects that are likely to cause errors in deep submicron high speed circuits. We focus on crosstalk due to capacitive coupling between a pair of lines. We first consider the case where crosstalk noise manifests as a pulse and characterize the maximum amplitude, width, energy and timing of this pulse. Closed form equations quantifying the dependence of these pulse attributes on the values of circuit parameters and the rise time of the input transition are derived. We also consider how crosstalk causes slowdown (speedup), i.e. increases (decreases) the rise/fall times of signals on coupled lines, when their inputs have transitions in the opposite (same) directions. Expressions relating the slowdown (speedup) to circuit parameters, the rise/fall times of the input transitions, and the skew between the transitions are derived. We show that crosstalk effects can be significantly aggravated by variations in the fabrication process. New design corners are identified for validation of designs that have significant crosstalk effects. Finally, the results of our analysis provide conditions that must be satisfied by a sequence of vectors used for validation of designs as well as post-manufacturing testing of devices in the presence of significant crosstalk.

147 citations


Patent
19 Dec 1997
TL;DR: In this paper, a disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. But the model of the current is based on a linear approximation to the exponential rise time of the coils current.
Abstract: A method to adaptively reduce error introduced by the coil current rise time. A disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. An adjustment to a commanded current value is based on the model of the coil current rise time and a magnitude change in commanded value. The model of the coil current is based on a linear approximation to the exponential rise time of the coil current. The commanded value is adjusted to compensate for the error in the control effort. For small commanded value differences no compensation is made for the coil current rise time. For medium command value differences a slope intercept equation is used to compute the compensated commanded value. For large commanded value differences half of an estimate of the maximum largest physical current change is used. The adjustment is made by the estimator in a position error signal feedback control system. The voice coil rise time adjustment is made to a voice coil motor control signal. The actuator velocity estimate is also improved with the model of the coil current rise time.

106 citations


Journal ArticleDOI
TL;DR: In this paper, a high sensitivity, high bandwidth, two-color interferometer (1064 and 532 nm) has been tested on the Hawk pulsed power generator at the Naval Research Laboratory.
Abstract: A high sensitivity, high bandwidth, two-color interferometer (1064 and 532 nm) has been tested on the Hawk pulsed power generator at the Naval Research Laboratory. The phase resolution is 10−5 waves with a rise time of 3 ns, a new capability for diagnosing plasmas, and neutrals in pulsed power experiments. The two-color feature is used to distinguish phase shifts from free (plasma) electrons and bound (neutral and ion) electrons. Simultaneous electron and neutral density measurements were demonstrated in a plasma opening switch (POS) experiment. The ability to measure small phase shifts with fast rise time were demonstrated in a plasma filled diode experiment. The high sensitivity and vibration isolation enable neutral gas distribution measurements from supersonic nozzles used in plasma radiation source experiments. Examples of these measurements and future applications are described.

78 citations


Journal ArticleDOI
TL;DR: The results of an experimental study, in which time-domain pulses are used to measure the far-field characteristics of an antenna, are presented in this article, where an X-band standard-gain horn has been used to verify the overall performance of the measurement system.
Abstract: The results of an experimental study, in which time-domain pulses are used to measure the far-field characteristics of an antenna, are presented. Pulses with duration and rise time of the order of 50 ps are generated, in order to characterize the complete frequency (1-18 GHz) behavior of an antenna. An X-band standard-gain horn has been used to verify the overall performance of the measurement system. Excellent agreement between the time-domain and the frequency-domain measurements has been observed. This paper describes the antenna time-domain measurement (ATDM) technique, time-domain gating, the error sources, and the advantages and the disadvantages of such a measurement technique.

61 citations


Journal ArticleDOI
TL;DR: A simple method to measure the contribution from acoustic phonons to the linear electro-optic effect is presented, and a negative contribution of r(a)(111) = -1.0 +/- 0.1 pm/V is obtained.
Abstract: We present a simple method to measure the contribution from acoustic phonons to the linear electro-optic effect. A step voltage with a short rise time (600 ps) is applied to the sample, and the electro-optic response is measured in the time domain. For the organic salt 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST), we obtained a negative contribution of r111a=-1.0±0.1 pm/V to the overall electro-optic coefficient of r111=48±5 pm/V λ=1535 nm. The electro-optic response was limited only by the rise time of the applied voltage, which corresponds to a frequency of 1 GHz.

50 citations


Patent
28 Jan 1997
TL;DR: In this article, a charge pump circuit with fast rise time and reduced physical area is described, which includes a plurality of stages having an non-uniform series of bootstrap capacitors.
Abstract: A charge pump circuit having a fast rise time and reduced physical area is disclosed. The charge pump includes a plurality of stages having an non-uniform series of bootstrap capacitors. By using non-uniform capacitors at the various stages, charging rise time is enhanced while at the same time reducing the overall physical size of the charge pump.

41 citations


Journal ArticleDOI
TL;DR: In this article, the authors evaluated the performance of infrared focal plane arrays (FPAs) made by bonding InSb detector arrays to CRC-744 multiplexers at the University of Rochester.
Abstract: Space astronomy requires large-area cryogenic infrared focal plane arrays (FPAs) with high quantum efficiency, extremely low dark current, low power dissipation, and background limited noise performance. To meet these requirements, especially at temperatures of 5–15 K, Santa Barbara Research Center designed and fabricated a new multiplexer, CRC-744. The FPAs made by bonding InSb detector arrays to CRC-744 multiplexers were evaluated at the University of Rochester. The best array achieved the read noise of 5 e − with 12 s integration and 7 e − with 200 s integration with Fowler-64 sampling at 15 K, the average dark current of <0.2 e−/ s at both 15 and 29 K, and the average quantum efficiency of 87% at both 15 and 29 K. The 10%–90% rise time was 4 μs driving a 600 pF external load. The power dissipation was 0.3–0.4 mW when running flat-out (100% duty cycle). The full well capacity was 105 e− (230 mV) with 400 mV of applied bias. The above test results demonstrate that the FPAs meet background-limited space ...

Proceedings ArticleDOI
01 Oct 1997
TL;DR: Silicon photodiodes have proven to be a versatile and useful complement to the standard photocathode detectors for soft x-ray measurement and are very competitive with diamond for a number of applications as discussed by the authors.
Abstract: Silicon photodiodes offer a number of advantages over conventional photocathode type soft x-ray detectors in pulsed power experiments. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. Silicon photodiodes available from International Radiation Detectors (IRD), Torrance, California have been characterized for absolute photon response from 1 eV to 10 keV photon energy, time response, and signal saturation levels. The authors have assembled individually filtered photodiodes into an array designated the XUV-7. The XUV-7 provides seven photodiodes in a vacuum leak tight, electrically isolated, low noise, high bandwidth, x-ray filtered assembly in a compact package with a 3.7 cm outside diameter. In addition they have assembled the diodes in other custom configurations as detectors for spectrometers. Their calibration measurements show factor of ten deviations from the silicon photodiode theoretical flat response due to diode sensitivity outside the center `sensitive area`. Detector response reproducibility between diodes appears to be better than 5%. Time response measurements show a 10-90% rise time of about 0.1 nanoseconds and a fall time of about 0.5 nanoseconds. Silicon photodiodes have proven to be a versatile and useful complement to the standard photocathode detectors for soft x-ray measurement and are very competitive with diamond for a number of applications.

Patent
03 Jun 1997
TL;DR: In this article, a sensor circuit with differential inputs Vi, Vo is used to reduce the rise time of a voltage Vo presented to a load, based on an input voltage Vi provided via an RC filter coupled to the load for removing higher frequency noise on Vo.
Abstract: The rise time of a voltage Vo presented to a load, based on an input voltage Vi provided via an RC filter coupled to the load for removing higher frequency noise on Vo, is substantially reduced by providing a sensor circuit with differential inputs Vi, Vo. The sensor circuit drives a charger circuit coupled to a DC potential and the load so that rapid charging of C to Vo does not depend on R. As Vo approaches Vi, the sensor circuit deactivates the charger circuit to stop further charging and a latch coupled to the sensor circuit shuts off the sensor circuit to reduce power consumption while (Vo˜Vi)>0. A current mirror buffer is desirably included between the sensor output and the latch for level shifting.

Patent
05 Sep 1997
TL;DR: In this paper, an earth-leakage monitoring method for a power distribution system, and in particular a DC 4-rail traction system, incorporating a pair of current-conductors (current rails) (16, 18) and an earth reference (a pair of running rails (10, 12) or an earthing system), is presented.
Abstract: An earth-leakage monitoring method for a power distribution system, and in particular a DC 4-rail traction system, incorporating a pair of current-conductors (current rails) (16, 18) and an earth reference (a pair of running rails (10, 12) or an earthing system), comprises measuring the conductor-to-earth voltage for each conductor; forming a ratio of these voltages; connecting a known resistance (R S ) between one conductor and earth; re-measuring the two conductor-to-earth voltages; forming a new voltage ratio, and calculating the value of leakage resistance (R L ) existing between each conductor and earth using the known resistance value and the two voltage ratios. An earth-leakage fault method is also disclosed in which the earth-leakage monitoring arrangement is adapted to continuously display the value of conductor-to-earth voltage of the two conductors, the power-distribution system having a number of such monitoring arrangements along its length; the behaviour of this displayed voltage is monitored, and the monitor with the fastest indicated voltage rise time is taken to be the monitor lying in the same section of the distribution system as the fault.

Journal ArticleDOI
TL;DR: In this paper, the behavior of laser ultrasound sources in isotropic metals using ultra-short laser pulses in the thermoelastic regime was investigated, and numerical results showed that the thermal response rates of both steel and aluminum are much faster than their mechanical response rates.

Proceedings ArticleDOI
22 Dec 1997
TL;DR: In this paper, it has been shown that the time walk effect can be reduced to more or less zero, for a dynamical range from single photon up to more than 1000 photons.
Abstract: The SPAD has proven already its capability of timing single- photon events with picosecond accuracy; it does that also for multi-photon events, but introduces here a time walk effect: with received energies of 1000 photons and more, the measured epoch time is shifted 200 ps or more towards earlier times; although the specific SPAD type used shows the lowest time walk effect of all measured silicon avalanche diodes, this effect still might introduce range errors of up to 30 mm, when measuring distances to satellites. It has been shown that this time walk effect is connected with a very small change of the avalanche rise time; this effect has been successfully used to develop an electronic circuit which measures this rise time difference, and uses it to compensate automatically almost all of the time walk effect. Some prototypes have been built and tested successfully in the satellite laser ranging station Graz; improved versions of the circuit are operated or tested now successfully in other SLR stations. It has been shown that the time walk effect can be reduced to more or less zero, for a dynamical range from single photon up to more than 1000 photons. For best time walk compensation, the circuit is adjusted for a specific laser pulse length; it has been shown however, that this adjustment also gives good time walk compensation for other laser pulse lengths.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Journal ArticleDOI
TL;DR: In this article, a high bandwidth measurement of the transient inter-subband photocurrent of a GaAs/AlGaAs multiple quantum-well infrared photodetector (QWIP) was performed.
Abstract: We report on a high bandwidth measurement of the transient intersubband photocurrent of a GaAs/AlGaAs multiple quantum-well infrared photodetector (QWIP). The photocurrent is excited via tunable subpicosecond infrared pulses. The response time of the detector has a full width at half-maximum of 18.5 ps and a rise time of 14.5 ps, which is limited by the electrical circuit. The decay time of the photocurrent response exhibits a significant dependence on the applied voltage, with increasing decay times for increasing bias voltages. From the experimental data, we conclude that the intrinsic response time of a QWIP is less than 7 ps.

Proceedings ArticleDOI
N. Foulon1, J.-P. Lucas, G. Barre, R. Mailfert, J. Enon 
22 Sep 1997
TL;DR: In this article, a fast voltage surge generator and laboratory cells have been built, to study partial discharge development and material degradation according to voltage magnitude, polarity, rise time and surge repetition rate.
Abstract: Electrical rotating machines are subjected to nonsinusoidal wave shapes when supplied from high frequency inverters. PWM (pulse width modulated) voltage sources with steep wave fronts can be destructive to the insulation and criteria normally used under sinusoidal conditions cannot necessarily be transposed to this new case. In order to determine the influence of this electrical stress, laboratory experiments were carried out to determine whether such repetitive voltage surges can precipitate premature failure of high voltage motor windings. A fast voltage surge generator and laboratory cells have been built, to study partial discharge development and material degradation according to voltage magnitude, polarity, rise time and surge repetition rate. Partial discharges (PD) are strongly dependent on the voltage waveform, related to the statistical time lag which is necessary before PD inception. Physical and chemical analysis and surface potential decay measurements show that the ageing process is related to the voltage waveform (frequency, shape factor, etc.). It is suggested that under PWM operation, insulation ageing mechanisms are predominantly controlled through an electrostatic phenomenon, different from the 50/60 Hz sinusoidal case.

Journal ArticleDOI
TL;DR: In this paper, a new application of the nonlinear transmission line (NLTL) for high-voltage pulse generation is reported, where the head-on collision of two solitons is quite effective to generate a highvoltage and short-width pulse.
Abstract: A new application of the nonlinear transmission line (NLTL) for high-voltage pulse generation is reported. In this NLTL, a rise time of an input pulse voltage of 20-kV amplitude can be reduced from 500 to less than 120 ns. Using this circuit, we demonstrated excitation of a pulsed CO/sub 2/ laser, and obtained output energy of 129 mJ at an efficiency of 4.3%. Moreover, we find that the head-on collision of two solitons is quite effective to generate a high-voltage and short-width pulse. The input pulse is doubled in amplitude and sharpened in width, from 3.6 kV-300 ns to 11 kV-76 ns. With this method, the utilization of semiconductor devices such as the SI thyristor is possible as a primary switching device. Finally, a xenon lamp has been flashed at a repetition rate of 1 kHz.

Patent
10 Mar 1997
TL;DR: A test instrument for testing magnet wire which is provided which tests, collects and permits analyzing the effect of temperature, frequency, voltage and rise time associated with magnet wire use, and more particularly, the effects of those variables on the insulation of the wire, so as to evaluate the magnet wire performance and inverter controlled dynamoelectric machine applications is described in this article.
Abstract: A test instrument for testing magnet wire which is provided which tests, collects and permits analyzing the effect of temperature, frequency, voltage and rise time associated with magnet wire use, and more particularly, the effects of those variables on the insulation of the wire, so as to evaluate the magnet wire performance and inverter controlled dynamoelectric machine applications.

Journal ArticleDOI
TL;DR: In this paper, a dynamic micromagnetic model which includes gyromagnetic effects via the Landau-Lifshitz equation and eddy currents has been developed and applied to the rise time problem in thin film write heads.
Abstract: A dynamic micromagnetic model which includes gyromagnetic effects (via the Landau–Lifshitz equation) and eddy currents has been developed and applied to the rise time problem in thin film write heads A cross-section of the part of the head covering the coils is simulated with this model, while the rest of the head is modeled as saturable reluctances The reluctances do not include eddy currents, but they do include leakage, fringing and saturation, and allow for computation of the deep gap field This model is used to study the details of the dynamics of the magnetization in the yoke as well as the dependence of rise time on geometric and material parameters It is found that switching starts at the surfaces of the pole and moves inward in “transition zones” Also, if rise time is defined as the time it takes the deep gap field to reach 7 kOe, the rise time increases with pole thickness but decreases with saturation magnetization and driving current

Journal ArticleDOI
TL;DR: In this paper, the authors describe the behavior of the magnetization rise time at the air-bearing surface of a thin film recording head, as a function of the amplitude of current pulses in the write coil.
Abstract: Time-domain optical measurements of magnetization dynamics can now be performed with sufficient resolution to reveal the intrinsic speed of many structures relevant to magnetic recording. Here we describe the behavior of the magnetization rise time at the air-bearing surface of a thin film recording head, as a function of the amplitude of current pulses in the write coil. The spatial profile of the magnetization on both sides of the gap is also examined through time-resolved, current dependent measurements. Spatial resolution enhancement via a solid immersion lens allows domain features to be discerned in the data.

Journal ArticleDOI
TL;DR: A novel termination metric is described that is based upon forcing the impulse response waveform to be symmetric using the first three moments of the distributed system response to provide an efficient means to trade off between signal rise time and ringing without requiring a time-domain simulation.
Abstract: The design of system level interconnects to meet signal integrity objectives is a challenging problem. This paper formulates the transmission line synthesis problem as a constrained multidimensional optimization task for performance-driven routing of the complete net, taking into account factors like loading conditions on the line, loss in the line, and rise time of the input signal. Different design variables, such as width or resistivity of the interconnect, resistive source, or far-end termination, etc., can all be considered concurrently. A novel termination metric is described that is based upon forcing the impulse response waveform to be symmetric using the first three moments of the distributed system response. This metric provides an efficient means to trade off between signal rise time and ringing without requiring a time-domain simulation. Several examples are presented to demonstrate the efficacy of the proposed methodology.

Proceedings ArticleDOI
20 Apr 1997
TL;DR: By allowing the upper switching level to be proportional to the velocity if it is possible to achieve a damped response, analogous to PD control for linear systems, effectively quenching the limit cycle.
Abstract: Further development of a three level switching controller (Grant and Hayward, 1995) is presented. The controller was originally designed to drive a novel shape memory alloy (SMA) actuator consisting of a number of thin NiTi fibers woven in a counter rotating helical pattern around supporting disks. While the original controller performed satisfactorily, it was hampered by the presence of limit cycles at higher gains. By allowing the upper switching level to be proportional to the velocity if is possible to achieve a damped response, analogous to PD control for linear systems, effectively quenching the limit cycle. With this damping, it is possible to decrease the rise time by almost half and maintain the same steady state accuracy.

Proceedings ArticleDOI
29 Jun 1997
TL;DR: The 80 kV all solid-state nanosecond pulser with rise time 0.9 ns, repetition rates up to 1 kHz and pulse duration of 2 ns is developed in this paper.
Abstract: The 80 kV all solid-state nanosecond pulser with rise time 0.9 ns, repetition rates up to 1 kHz and pulse duration of 2 ns is developed. As the basic switches in the generator drift step recovery diodes (DSRD) and fast ionization dynistors (FID) are used. That allows creation of the outlet power block generating voltage pulse with amplitude 80 kV, with dimensions of 150/spl times/150/spl times/100 mm. The efficiency of the generator is about 35%. As a cooling subsystem an air-oil system pumping of oil through the power block is used. Special high-voltage connectors capable of transmitting voltage pulses with amplitude up to 100 kV and edges less than 0.5 ns, are developed. An attenuator was also developed that allowed output voltage of the generator to be measured.

Journal ArticleDOI
TL;DR: In this article, the development and experimental investigation of a large-current radiator with a pulse generator using avalanche transistors is reported, which is intended for radiating nonsinusoidal pulse electromagnetic waves with a duration of 2 ns.
Abstract: The development and experimental investigation of a large-current radiator (LCR) with a pulse generator using avalanche transistors is reported. The LCR is intend for radiating nonsinusoidal pulse electromagnetic waves with a duration of 2 ns. The radiated field strengths in both the near and the far field are measured. The LCR described produces magnetic field strengths of about 4.2 mA/m at a distance of 5 m for radiator current amplitudes of about 0.7 A with rise time of 1 ns. The width of the antenna pattern, measured by the drop of the field strength to one half of its peak value is 120/spl deg/.

Proceedings ArticleDOI
01 Jul 1997
TL;DR: In this paper, a conventional pulse transformer with a rise time of 250 ns and a pulse droop of 3.6% has been designed and analyzed using a simplified lumped circuit model.
Abstract: The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250 ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented.

Proceedings ArticleDOI
29 Jun 1997
TL;DR: In this paper, the results of the multi gap, multi channel switch development performed at the High Current Electronics Institute in order to reach the requirements of the SYRINX project (France).
Abstract: The switches that are designed for application in high pulsed power drivers should meet some hard requirements, the main of them being small inductance and big charge flowing through the switch. In order to reduce the inductance and to increase the charge it is preferable to divide the switched current into multiple parallel channels. Such parallel current channels could be obtained in railgap three-electrode switches, or in surface switches, due to electrical field disturbance which occurs when a trigger pulse rising as -10/sup 13/ V/s is applied to the switch. Multi channel discharge could also be realized in multi gap spark switches. We report the results of the multi gap, multi channel switch development performed at the High Current Electronics Institute in order to reach the requirements of the SYRINX project (France). These requirements are: operating voltage 90 kV, switch current >500 kA, current rise time <1/spl mu/s, and switch inductance <10 nH. Different switches are described developed in consecutive steps of our collaboration. In these switches, the multi channel discharge is realized in multi gap spark switch configuration, where the voltage during charging is uniformly distributed between the few gaps connected in series. The triggering occurs due to disturbance of voltage distribution between the gaps when a trigger pulse is applied. The number of parallel current channels is controlled by the number of parallel multi gap chains.

Proceedings ArticleDOI
30 Oct 1997
TL;DR: In this article, a high voltage stimulator was designed to allow transcutaneous stimulation of tactile fibers of the fingertip, and the output stage was based upon an improved Howland current pump topology, modified to allow high load impedances and small currents.
Abstract: A high voltage stimulator has been designed to allow transcutaneous stimulation of tactile fibers of the fingertip. The output stage is based upon an improved Howland current pump topology, modified to allow high load impedances and small currents. The current output accuracy is better than 15% for 1 to 10 mA for 30 /spl mu/sec pulses. The rise time for square pulses is less than 2 /spl mu/sec. Common mode latch-up power supply problems are discussed.

Journal ArticleDOI
TL;DR: In this paper, the conductance transient of three thick-film tin oxide gas sensors under successive step rises in the gas concentration is analyzed and the measured set of rise times is characteristic for each sensor - gas pair and may give useful information for gas recognition.
Abstract: Dynamically characterizing the electrical response of chemical sensors is a strategy to improve their selectivity. In this paper, the conductance transient of thick-film tin oxide gas sensors under successive step rises in the gas concentration is analysed. The transient response of three thick-film tin oxide gas sensors in the presence of organic solvent vapours (toluene, o-xylene and ethanol) has been measured. As a main result, it has been found that, although the first step in the conductance-transient rise time is concentration independent, for the second and successive steps, decreases and becomes concentration dependent. This behaviour has been modelled successfully with a nonlinear diffusion - reaction model. The measured set of rise times is characteristic for each sensor - gas pair and may give useful information for gas recognition. Furthermore, the successive injection of gas samples during the sensor-calibration procedure may be a time-saving technique.