Improved time-base for waveform parameter estimation

An improved gated oscillator time-base and associated auto-calibration algorithm for use in a high-accuracy sampling waveform acquisition system are described. The time-base architecture consists of a stable 100 MHz gated oscillator, 24-bit counter chain, and a clock period interpolator. The nominal, uncorrected linearity of the time-base is approximately ±30 ps. By using an iterative, sine-fit based algorithm, the linearity has been improved to <5 ps. Details of the performance and major sources of error of the time-base and correction algorithm in an equivalent time sampling system are also discussed     

Design of a flash-based reference voltage generator for drain bias circuit

The design of a flash-based reference voltage generator used to generate the drain bias reference voltage for flash sensing is described. The flash cell drain must maintain a stable voltage during read operation, irrespective of supply voltage within the chip, to avoid drain disturb condition. Since this reference voltage needs to supply the entire chip, the high capacitance associated with this node usually requires a long time to power-up. A scheme used to reduce the power-up time by a factor 20times from conventional design, while maintaining the design required precision of 2% in the reference voltage output is described. Since the circuit is also required to be ON during the entire operational phase of the chip, design methods used to lower the current consumed by the circuit using a sample-and-hold scheme are also discussed     

A Digital Interpolation Technique in Time Measurement

The problem of measuring a time interval using a crystal oscillator as a time base is discussed. A statistical analysis is made of the free-running oscillator and gated counter when the time interval to be measured is repetitive. Using the equivalent circuit of a quartz crystal, the difficulties involved in using a pulsed crystal oscillator as a time base are investigated. A method is described to measure, at a random instant, the instantaneous phase of a free-running oscillator and use this information as the last significant figure in a time interval or pulse delay method. The method consists of sensing the coincidence between oppositely-traveling pulses on a delay line. A digital-delay generator was constructed using this technique. The accuracy of the delay was measured as ±0.01 us ±crystal time-base accuracy. The construction and testing of this device is discussed.     

A simple power supply and control unit for pulsed operation of a microchannel plate imaging detector

A simple power supply and control electronic system to operate microchannel plate (MCP) detectors for imaging transient events such as X-ray emission from laser-produced plasmas is described. The power supply consists of two parts, viz. a high voltage pulse generator of 1 kV amplitude with a variable pulse duration of 100 μs to 1 ms for the MCP input, and a regulated 5 kV d.c. for biasing the phosphor screen. The control unit synchronizes the high voltage pulse with the event and operates a safety switch to guard the detector against any accidental rise in the background pressure. A signal-to-noise ratio ≥ 75 is obtained, limited by the noise contribution of the Charge Coupled Device (CCD)-frame grabber combination attached to the MCP. The system is compact, has provision for both positive and negative pulses, is extendable to higher voltages for operating two-stage MCP, and is immune to electromagnetic interference.     

Development and Application of a Programmable Partial Discharge Calibrator

A programmable partial discharge (PD) calibrator composed of an arbitrary waveform generator that is series connected to a capacitor is described. The voltage waveform supplied by the generator is software controlled. The characteristics and capabilities of the calibrator are presented, and the procedures used for its characterization are discussed. The calibrator can reproduce different types of pulses, which include both the corona and PDs of random amplitudes and the predetermined phase relationship with respect to the high-voltage (HV) supply. Examples of the actual discharges measured in the laboratory are compared with the corresponding pulse sequences generated by the calibrator. Finally, by means of this developed instrument, the performances of four partial-discharge-measuring systems equipped with analog and digital measuring instruments are investigated and compared by generating suitable pulse charge sequences.      

R.F. diode sputtering in permanent-match mode

A constans-voltage r.f. diode sputtering set incorporating a self-excited oscillator was designed. The variable discharge impedance was stabilized, as seen from the r.f. generator output, by suitable capacitive discharge shunting combined with a rather tight coupling to the generator. A conventional r.f. power oscillator of the Colpitt type was used and, as the loading of the oscillator by the discharge and its associated electrical network was essentially constant, there was no need for an impedance matching network or voltage-and/or power-controlling servosystems to assure stable operation of the equipment.For bias sputtering, the variation in the substrate holder voltage was established by variation of the mutual inductance to the bias circuit which allows the bias voltage to be operated in phase or 180° out of phase with respect to the target voltage. The r.f. generator had a line-modulated power supply; its influence on the accelerating voltages governing sputtering was considered and the ion energy distribution was studied. The operation of the equipment is illustrated by refractive index results obtained in TiO₂ films deposited by in-phase and inverse-phase bias sputtering.     

高速采样示波器中的时基失真及其估计

介绍了时基失真的概念及产生原理。改进了美国NIST提出的时基失真的数学模型，据此模型仿真出时基失真的数据，进而仿真出测量数据。给出了为估计采样示波器的时基失真所采取的方法——最小二乘法。这种方法需要在多相位、多频率上测量信号，可以精确地估计谐波模型的阶数。最后介绍了如何根据已经得到的估计值来修正时基失真。     

A uniform amplitude spectrum generator for test of the maximum effective pulse rate of MCAs

This paper describes a two dimensional random pulse generator with output pulses which are both random in time and amplitude. It creates a pulse amplitude spectrum with statistically uniform distribution. Besides, a high resolution stable pulse (reference peak) is also produced just beyond the high end of the spectrum. This generator is designed to replace the radioactive source in testing MCAs or computerized data acquisition and processing systems. Especially, the shift of channel address and the resolution of pulse amplitude of MCAs can be measured precisely and easily by this generator at various input pulse rate.     

2 cm spatial-resolution and 2 km range Brillouin optical fiber sensor using a transient differential pulse pair

We report a high-spatial-resolution and long-range distributed temperature sensor through optimizing differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA). In DPP-BOTDA, the differential signal suffers from a signal-to-noise ratio (SNR) reduction with respect to the original signals, and for a fixed pulse-width difference the SNR reduction increases with the pulse width. Through reducing the pulse width to a transient regime (near to or less than the phonon lifetime) to decrease the SNR reduction after the differential process, the optimized 8/8.2 ns pulse pair is applied to realize a 2 cm spatial resolution, where a pulse generator with a 150 ps fall-time is used to ensure the effective resolution of DPP-BOTDA. In the experiment, a 2 cm spatial-resolution hot-spot detection with a 2 °C temperature accuracy is demonstrated over a 2 km sensing fiber.     

Low-jitter trigger system for pulse calibration and intercomparisonof high-speed samplers

A low-jitter (<1 ps) trigger system for pulse-waveform-based calibration and intercomparison of high-speed samplers is described. The system uses a commercially available pulse generator and pulse splitter/delay line     

新型高功率因体激光器电源

用旋转磁通压缩脉冲发电机作为高功率固体激光器电源是一条新的技术路线,该类电源具有小型、机动、灵活、可靠、寿命长等特点。本文通过比较了各种类型脉冲电源的性能指标,解释了旋转磁通压缩、串级、自激、偏极与双机同壳等原理,给出电机的设计公式和一１０ＭＷ串级主动旋转磁通压缩脉冲发电机的设计与实验结果。     

The Design and Tests of Battery Power Supply System for Pulsed Flat-Top Magnets in WHMFC

A capacitor bank power supply of 14.8 MJ is built in Wuhan National Pulsed High Magnetic Field Center (WHMFC). Another pulse generator power supply of 100 MJ/100 MVA is expected to be finished by the end of August, 2012. These power supplies can drive pulsed magnets with a magnetic field of 50 T to 80 T and a pulse duration of 15 ms to 1000 ms (Li et al. in IEEE Trans. Appl. Supercond. 18:596, 2008). In addition to that, a new battery bank power supply system is also designed. This system can output a maximum voltage of 1000 V, a maximum current of 40 kA and a pulse duration of 2 s to feed pulsed flat-top magnets of 40 T/2 s. This power supply consists of battery bank and its charger, thyristor DC switch and its forced commutation, DC breaker, control system, Crowbar, PWM controller and magnet. The battery bank uses 945 lead-acid batteries and its modular design makes it easy to modify the voltage and current of the power supply by changing the connections of the batteries based on the requirement of single-coil, double-coil and triple-coil magnets. The design and primary tests of the battery power supply system will be introduced in this paper (Schillig et al. in IEEE Trans. Appl. Supercond. 10:526, 2000).     

Design and construction of double-Blumlein HV pulse power supply

A double Blumlein pulse generator is constructed using a coaxial cable. This power supply is capable of providing a voltage up to 20 kV across a matched load and 40kV across an open load with a charging voltage of 10 kV. It is designed to provide a pulse width of 110ns. A rise time of ∼10ns is obtained with present spark gap. A rotating spark gap is also designed and constructed to get a pulse repetition rate of 25Hz. Although, in the present work this pulse generator is used to study the streamer discharge in air, it is useful in many other applications also.     

Chaotic pulse trains generated by a dynamical system driven by a periodic signal

Chaotic pulse trains (rf pulses) can be generated by a dynamical system driven by a periodic signal. This possibility is demonstrated using a generator of chaotic oscillations with 2.5 degrees of freedom. By controlling the frequency of external action and selecting a constant bias (working point), it is possible to vary the width of rf pulses and their repetition rate within broad limits.     

Pulse Generator and Flip-Flops

A simple pulse generator can be constructed using IC gates. Such a pulse generator is described and its use to construct edge-triggered flip-flops is demonstrated. A flip-flop for use in a phase comparator is described. Desirable and undesirable characteristics for this application are discussed and examples of R-S and J-K flip-flops given.     

Instrumental resistance-frequency converter chip

A special-purpose analog integrated circuit chip is described that converts the ratio between the temperature transducer resistance to a certain reference resistance into repetition period of pulses of fixed duration. The chip includes circuits for resistance current and current-oscillation period converters, and a current pulse generator in the power supply section. Stability of converter parameters is ensured by using supplies with temperature-stabilized current drift.Translated from Izmeritel'naya Tekhnika, No. 11, pp. 52–54, November, 1994.     

Calibration of a Kerr Cell System for High-Voltage Pulse Measurements

Several techniques for calibration of an electrooptical (Kerr cell) high-voltage pulse measuring system are described. Independent calibrations, without reference to pulse divider measurements, are achieved by application of a direct bias voltage to the Kerr cell. After calibration, experiments with voltages as high as 100 kV demonstrate reasonable agreement (to within 1 percent) between simultaneous Kerr cell and calibrated pulse divider measurements.     

Time-base nonlinearity determination using iterated sine-fitanalysis

A new method is presented to determine the time-base errors of sampling instruments. The method does not require a time-base error model and thus provides accurate estimates where model-based methods fail. Measurements of sinewaves at multiple phases and frequencies are used as test signals. A harmonic distortion model is used to account for amplitude nonlinearity of the sampling channel. Use of an independent method for estimating the channel noise and jitter allows an accurate estimate of the harmonic order. Methods are presented for separating the harmonics generated by the sampling channel from those generated by the time-base distortion. The use of an iterative sine-fit procedure gives accurate results in a short time. A new weighting procedure is described, which minimizes the error in the estimates. Guidelines are given for selecting good sets of test frequencies. Results are shown for both simulated and real data     

A low-cost bipolar pulse generator for high-frequency ultrasound applications

A design of a low-cost bipolar pulse generator for high-frequency (HF) ultrasound applications is presented. The pulse generator can produce N cycle (1-255 cycles) bipolar pulses with center frequency over 60 MHz. The measured pulse amplitude was over 160 Vpp, and the pulse ringing was less than 0.3 Vpp (i.e., signal-to-ring ratio is 55 dB). The pulser can be used in high-frequency ultrasound Doppler and B-mode imaging applications with arrays.     

High-bandwidth laser-pulse generator using continuous-wave lasers

A laser-pulse generator for the transfer of continous-wave (cw) absolute radiometric calibrations to high-speed pulse photodetectors is described. The cw input lasers are modulated by a spinning polygon mirror in a ring cavity to produce high-speed, constant-amplitude, constant-shape laser pulses. Constantamplitude outputs range temporally from cw to 15-ns full-width at half-maximum (FWHM) Gaussian pulses. An all-reflective optical design permits operation of the device from the visible to the far-infrared spectral regions. Design and performance estimates for the pulse generator as well as experimental verification are presented.