Pulse Pattern Generator Research Articles

A new Pulse-Pattern Generator based on LabVIEW FPGA

For the control of experimental sequences composed of triggers, gates and delays a Pulse-Pattern Generator (PPG) has been developed based on a Field Programmable Gate Array (FPGA) addressed in a LabVIEW environment. It allows a highly reproducible timing of measurement procedures by up to 64 individual channels with pulse and delay periods from the nanoseconds to the minutes range. The PPG has been implemented in the context of the development of a new control system for the ClusterTrap setup, an ion storage device for atomic-cluster research, in close contact with the SHIPTRAP and ISOLTRAP collaborations at GSI and CERN, respectively. As the new PPG is not ion-trap specific it can be employed in any experiment based on sequences of triggers, pulses and delays.

Utilization of a cryo-prober system for operation of a pulse-driven josephson junction array

We demonstrated the operation of pulse-driven Josephson junction arrays (JJAs) for AC voltage standard using a wideband cryo-prober system with a 4-K Gifford-MacMahon (GM) cooler. This unique system was originally developed for high-speed network switch applications of rapid-single-flux-quantum (RSFQ) circuits and enables wideband data transmission at bit rates of higher than 10 Gbps between room-temperature and cryogenic environments. JJA chips were fabricated using NbN-based superconductor-normal metal-superconductor (SNS) junctions. A 5-mm chip was mounted on a 16-mm chip carrier using flip-chip bonding technology for probe contact. To obtain bipolar output voltages, we tried two types of testing based on the AC coupling technique proposed by the National Institute of Standards and Technology (NIST). A pulse pattern generator (PPG) with a large memory of 134 Mbit was used for covering a wide frequency range of output signals. As a result, we succeeded in bipolar operation of the JJA, generating waveforms at frequencies from 60 Hz to several tens of kilo hertz. The maximum rms voltage obtained for a single array was 12.7 mV. The observed spurious level was lower than -93 dBc at 16 kHz.

A new coding technique in serial data transmission and demodulation with Josephson junctions array

We have developed a coding technique to drive an overdamped Josephson junction array (JJA) using modulated optical pulses for voltage standard applications. Our system is composed of a multi-channel pulse pattern generator (PPG), a LiNbO3 (LN) modulator with an electrical multiplexer (MUX), a photodiode (PD), and an over-damped JJA cooled with 4 K GM cryocooler. The modulated optical pulses are transmitted via an optical fiber to a PD that is installed close to the JJA on a cold stage, and they are then converted into an electrical current pulse train in order to drive the JJA. To avoid a problem in our LN modulator system, i.e., the duty-ratio dependence of the output pulse waveform, pseudo signals that maintain the duty ratio at approximately 50% are inserted in the original bit stream. We demonstraited that this technique is applicable for arbitrary return-to-zero (RZ) binary bit streams.

Sub-$\mu{\rm m}$ SNS Josephson Junction Arrays for the Josephson Arbitrary Waveform Synthesizer

The experimental set-up of a Josephson arbitrary waveform synthesizer (JAWS) has been further optimized to generate AC voltages with fundamental accuracy. Josephson junction series arrays for the JAWS, consisting of sub-mum SNS type junctions (superconductor-normal conductor-superdonductor), are fabricated using a technology which combines electron-beam lithography and chemical-mechanical polishing. Bipolar pulses are realized by the superposition of unipolar pulses from a pulse pattern generator and a continuous sinusoidal microwave provided by a signal generator. A second-order delta-sigma modulator is optimized to generate a high-quality pulse code.

Gigabits-per-Second Signal Transmission from Single-Mode Vertical-Cavity Surface-Emitting Laser via Thin-Film Waveguide for Wavelength-Division-Multiplexing Optical Interconnect Board

A wavelength-division-multiplexing (WDM) optical interconnect board providing broad-band transmission from a two-dimensional (2D) array of vertical-cavity surface-emitting lasers (VCSELs) to a 2D array of photodetectors is one of the attractive candidates for constructing future ultrahigh performance signal processing systems. Focusing grating couplers and distributed Bragg reflectors were integrated into a thin-film glass waveguide to form free-space-wave optical add/drop multi/demultiplexers required for the WDM optical interconnect board. A single-mode VCSEL was placed at the focal point of a focusing grating coupler, and a diverging wave from VCSEL was coupled and collimated into the waveguide. After 15 mm propagation, the guided wave was dropped by an optical drop demultiplexer to a focusing wave in free space. VCSEL was driven directly by a pulse pattern generator and the transmitted signal was detected. An open eye diagram of a 1 Gbps pseudo-random-binary-sequence non-return-to-zero signal was confirmed.

Superconducting NbN nanowire photo switches for generating single flux quantum pulses

We investigated superconducting NbN nanowire as a photo switch for generating single flux quantum (SFQ) pulses. Epitaxially grown NbN thin films were prepared on MgO(100) substrates by a dc magnetron sputtering method using gas mixture of Ar+N2, without substrate heating. NbN thin films showed Tc of 13.6 K for 8 nm, and 10 K for 4 nm. NbN nanowires were patterned using a electron beam lithography with 200 nm thick electron beam resist. To increasing photo-sensitive regions, we fabricated 50 × 50 μm2 meander patterns with NbN nanowires. Line width of nanowires was varied from 150 nm to 500 nm. Critical current density of NbN nanowires was about 3×106A/cm2 at 4.2 K. We irradiated 850-nm laser pulses via 50-μm multi-mode optical fibers. Repetition frequency and pulse width could be controlled by a pulse pattern generator. The maximum laser pulse power was about 1 mW. Using 150-nm-wide NbN nanowires, half of critical current was suppressed by 1 mW CW laser irradiations. High speed responses were observed for laser pulses with repetition frequency of 1 MHz and pulse width of 2 ns. Besides the NbN nanowire photo switches, we designed an SFQ interface circuit based on Josephson transmission lines. The designed circuit could generate SFQ pulses by input current of 10 μA, 25 GHz current pulses. Dc bias margin of the circuit was ±15% for 60 μA current pulses.

SNS Josephson Junction Series Arrays for the Josephson Arbitrary Waveform Synthesizer

The Josephson arbitrary waveform synthesizer (JAWS) allows AC voltages to be generated with fundamental accuracy. Lumped arrays of superconductor/normal conductor/superconductor (SNS) Josephson junctions were developed and investigated for this application. Combining electron-beam lithography and chemical-mechanical polishing, series arrays of sub-micrometer SNS junctions consisting of Nb/HfTi/Nb were fabricated. The junction size varied from 0.04 mum2 to 4 mum2 in series arrays up to 2560 junctions in different microwave designs. Stable Shapiro steps are generated in a frequency range from 5 GHz to 20 GHz using continuous microwave irradiation. Using a simple pulse pattern at different pulse repetition frequencies, the arrays show current-voltage characteristics with flat Shapiro steps. Sinusoidal AC voltages were synthesized using a commercial pulse pattern generator. Peak-to-zero voltages of some mV for frequencies below 1 kHz were achieved. Higher harmonics were measured to be more than 80 dB below the fundamental tone. The behavior of the arrays was investigated in more detail by measuring the amplitude-frequency spectra.

A Cross-Type SNS Junction Array for a Quantum-Based Arbitrary Waveform Synthesizer

Central to quantum-based arbitrary waveform synthesizers is a Josephson junction array driven by short pulses. Its linear dimensions should be small compared to the line wavelength in order to generate an ac voltage with quantum accuracy. Therefore, we use coplanar strip transmission lines to integrate a large number of cross-type SNS Josephson junctions into multiple parallel arrays. First measurements show that a circuit with 1,760 junctions exhibits Shapiro steps over a large frequency range. By using pulse driving the chip generates unipolar voltages up to 6.4 mV at a clock frequency of 3.5 GHz, the maximum frequency of the available pulse pattern generator.

Controlling high-frequency chaos in resonant tunneling chaos generator circuits

Controlling chaos signal patterns at 12GHz was demonstrated on the resonant tunneling chaos generator circuit. This was made possible by implementing the reset switch, which resets the circuit to various initial conditions periodically. The reset period was set so short that the initial condition errors can not grow significantly. Thus the circuit repeated identical signal patterns, and they can be clearly observed by a sampling oscilloscope. The application of this circuit to fabricate ultrahigh speed pulse pattern generator was also discussed in this paper.

Direct Self-Control and Synchronous Pulse Techniques for High-Power Traction Inverters in Comparison

High-power inverters for traction drives employ in the upper range of stator frequency special pulse control methods, optimized synchronous pulsewidth modulation (PWM), mainly in combination with rotor-flux-oriented control schemes, and direct self-control (DSC) which encompasses motor control and pulse pattern generation. The well-known symmetrized sinusoidal PWM is only to be used in the lower speed range. This paper presents and compares exemplarily the stationary behavior of these two control methods; criteria are inverter peak current, motor harmonic losses, torque ripple, and DC-link harmonics. For these low switching frequencies DSC shows, in spite of its simplicity, a very good overall performance, mainly by avoiding the imperfect use of switching frequency by the synchronous pulse patterns.

Feasible enhancement of a three‐phase soft‐switching inverter with an auxiliary resonant DC link snubber

AbstractThe purpose of this paper is to improve power conversion efficiency of a three‐phase voltage source type soft‐switching inverter with a single auxiliary resonant DC link (ARDCL) snubber. First, the operating principle of an ARDCL snubber discussed here is described. Second, this paper proposes an effective pulse pattern generation method of the zero voltage space vector of the three‐phase soft‐switching inverter using IGBTs or power modules that can reduce power losses in the ARDCL snubber treated here. In particular, a zero voltage holding interval in the DC rail busline of this three‐phase soft‐switching inverter is to be regulated according to the generation method of the zero voltage space vector. Third, the maximum modulation depth Mmax under the condition of correction of the instantaneous voltage space vector can be improved by using a new zero voltage space vector generation method. Finally, the feasible experimental results of this inverter are obtained confirming the operating characteristics such as power conversion actual efficiency, as well as conventional efficiency THD and RMS value of the balanced three‐phase output voltage for an experimentally built three‐phase voltage source type soft‐switching pulse modulated inverter using the latest IGBT modules and evaluated from the standpoint of practical applications in industry UPS and new energy systems. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 89–99, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10234

Hardware simulator for photon correlation spectroscopy

We present a hardware simulator ideal for testing digital correlators in photon correlation spectroscopy. By using a PCI-6534 National Instrument I/O board, a personal computer (1.5 GHz Pentium 4), and an original algorithm developed in LabVIEW (National Instrument™), we realized an instrument capable of delivering a continuous stream of transistor-transistor logic pulses with the desired statistical properties over one or more channels. The pulse resolution could be set to values multiple of the clock period Δt=50 ns available on the board. When a single channel is used, the maximum count rate at Δt=50 ns was 〈I〉∼350 kHz. With two channels we obtained 〈I〉∼80 kHz at Δt=50 ns and 〈I〉∼120 kHz at Δt=100 ns. Pulse streams with Gaussian statistics and in the presence of shot noise were simulated and measured with a commercial hardware correlator. Photodetector defects, such as the presence of afterpulses, were also simulated and their elimination by cross correlation techniques was checked. The simulator works also as a general purpose pulse pattern generator (PPG). Compared with commercial PPGs, our simulator is slower, but permits a continuous output of the pulse stream (not allowed in PPGs). At the same time it offers many other nontrivial advantages related to its flexibility, relatively low cost, and easy adaptability to future technology developments.

A Static Synchronous Converter for Power Conditioning in Network Distribution with High Wind Energy Share

The integration of renewable energy sources, e. g. wind energy in weak or isolated power systems produces disturbances. Such disturbances are due to the power fluctuations caused by the stochastic fluctuating wind energy, current harmonics in the power system, switching operations, tower effects and reactive power consumption of the wind energy installations. These decrease the power quality at the point of common coupling (PCC). This paper introduces a concept to compensate the disturbances by the use of a static synchronous converter with an active damping circuit. This new concept is based on the principle of the static reactive power converter, and was extended by means of system integration of largely standardized components of the drive-converter technology. In combination with an active intervention in the pulse-pattern generator of the main converter, it is possible to balance asymmetrical loads and compensate the harmonics. The pulse pattern generator was realized through an assembler-programmed PC.

Three-Dimensional Imaging System Using Ultrasonic Encoded Wavefront –High Speed Computation and Array Geometry

We are developing a computed ultrasonic 3-D imaging system based on encoded wavefront transmission which enables acquisition of 3-D images with a very high flame rate. We have developed an underwater 3-D imaging system based on the proposed method. In order to expand our system to various applications including medical imaging, we are designing a new imaging system. The present data acquisition system consists of multi channel A/D converters and a pulse-pattern generator. A transducer array is now under development, with polymer and composite piezoelectric films. Computation is accelerated with a DSP coprocessor board. In this paper, we describe high-speed 3-D image reconstruction using sector-like grid geometry. Influence of the array configurations to artifact level are investigated using computer simulations.

Three-phase buck/boost-type high-power-factor switching converter

The harmonic pollution caused by ac-to-dc converters has been of great concern. To overcome this problem, several power-factor-correction (PFC) converters have been developed and applied in recent years. However, several power converter systems, such as the motor drive system, with a wide V/F control range, uninterruptible power supply system and dc power supply system with universal input voltage range, require an ac-to-dc converter or an off-line converter (preregulator) with a wide output-voltage control range in order to be highly efficient. However, the most conventional PFC converters employ a voltage-fed or current-fed type topology and they have a lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high-system efficiency. On the other hand, a buck/boost converter has a wide control range of the output voltage and acts in PFC operation under an appropriate control technique. Thus, study of the possibility of using the buck/boost ac-to-dc converter with PFC and a wide output-voltage control range is important to the realization of harmonic-free and efficient power conversion systems. In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes the following two new techniques. One is the pulse integral value modulation that compensates modulation errors in conventional pulse-width-modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge as a way to simplify the pulse pattern generation process. This paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed buck/boost converter system. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 41–55, 1997

Three‐phase buck/boost‐type high‐power‐factor switching converter

The harmonic pollution caused by ac-to-dc converters has been of great concern. To overcome this problem, several power-factor-correction (PFC) converters have been developed and applied in recent years. However, several power converter systems, such as the motor drive system, with a wide V/F control range, uninterruptible power supply system and dc power supply system with universal input voltage range, require an ac-to-dc converter or an off-line converter (preregulator) with a wide output-voltage control range in order to be highly efficient. However, the most conventional PFC converters employ a voltage-fed or current-fed type topology and they have a lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high-system efficiency. On the other hand, a buck/boost converter has a wide control range of the output voltage and acts in PFC operation under an appropriate control technique. Thus, study of the possibility of using the buck/boost ac-to-dc converter with PFC and a wide output-voltage control range is important to the realization of harmonic-free and efficient power conversion systems. In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes the following two new techniques. One is the pulse integral value modulation that compensates modulation errors in conventional pulse-width-modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge as a way to simplify the pulse pattern generation process. This paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed buck/boost converter system. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 41–55, 1997

Widely tunable electrooptic pulse-pattern generation and its application to on-wafer large-signal characterization of ultra high-speed electronic devices

A pulse-rate-tunable, electrooptic pulse-pattern generator and a wideband high-efficiency optical-to-electrical (OE) conversion stimulus probe have been developed. Sinusoidal electrooptic amplitude/phase modulation and chirp compensation were used to provide picosecond pulsation, and the relationship between pulse-rate tunability and the extinction ratio has been studied analytically and experimentally. Return-to-zero (RZ) pylse patterns of 10–72 Gb s−1 have been generated by using LiNbO3 amplitude/phase modulators with a bandwidth of 18 GHz, a single dispersion shifted fibre, and a time-division multiplexer. A 1.55 μm waveguide p-i-n photodiode yielded high responsivity (0.75 A W−1) and a saturation peak voltage of 200 mV at the probe tip. The measured effective 3 dB bandwidth exceeds 50 GHz, which is currently limited by the frequency dispersion of the coplaner waveguide (CPW) used in the probe. Use of this generator and probe, in combination with electrooptic sampling, for on-wafer characterization of a broadband distributed amplifier revealed the amplifier's saturation characteristics and waveform distortion under actual operating conditions with a 64 Gb s−1, 120 mV per probe, RZ pulse-pattern input.

10-80-Gb/s highly extinctive electrooptic pulse pattern generation

A pulse-rate-tunable, highly extinctive, ultra-highspeed electrooptic pulse pattern generator has been developed. The optical short pulse generation is based on sinusoidal electrooptic phase modulation and linear chirp compensation using a dispersive medium. Filtering the nonlinear chirp components generated by sinusoidal phase modulation drastically improves the pulse extinction, and makes nearly background-free picosecond pulsation over a wide pulse-rate range even when the group delay dispersion value is fixed.

Demonstration of programmable optical pulse patterngeneratorfor 100 Gbit/s networks

A programmable 100 Gbit/s optical pulse pattern generator based on planar silica delay lines and semiconductor laser amplifier switches is demonstrated experimentally. The technology has key applications in ultrafast all-optical networks.

Three-Phase Buck/Boost-type High-Power-Factor Switching Converter.

The harmonic pollution caused by ac-to-dc converters has been our great concern. To overcome the problem, several Power-Factor-Correction (PFC) converters have been developed and applied in practice in recent years.However, several power converter systems, such as motor drive system with a wide V/F control range, uninterruptible power supply system, and dc power supply system with an universal input voltage range, require an ac-to-dc converter or an off-line converter (pre-regurator) with a wide output-voltage control range to obtain high efficiency. But the most conventional PFC converters employ a Voltage-Fed or Current-Fed type topology and they have lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high system efficiency.On the other hand, a Buck/Boost converter has a wide control range of the output voltage and acts PFC operation under an appropriate control technique. Thus, the study of a possibility about the Buck/Boost ac-to-dc converter with PFC and a wide output-voltage control range is important to realize harmonic-free and efficient power conversion systems.In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes following two new techniques. One is the “Pulse-Space-Modulation” to compensate modulation errors in conventional Pulse-Width-Modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge, to simplify the pulse pattern generation process.In the following, the paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed Buck/Boost converter system. Finally, the paper concludes the contents of this paper.