Fall Time Tf Research Articles

Squeeze-Type Piezoelectric Inkjet Printhead Actuating Waveform Design Method Based on Numerical Simulation and Experiment.

The piezoelectric inkjet printing technique has been commonly used to produce conductive graphics. In this paper, a trapezoidal waveform design method for squeeze-type piezoelectric inkjet printhead is presented to provide a modified steady ejection and optimal droplet shape, in which a coupled multi-physics model of a piezoelectric inkjet printhead is developed. This research describes the effects of parameters, including rising time tr, falling time tf, and dwelling time td, of the trapezoidal waveform on the pressure at the nozzle through numerical simulations. These parameters are initially optimized based on numerical simulations and further optimized based on experimental results. When the printhead is actuated by the optimized waveform with the tr = 5 µs, td = 10 µs, and tf = 2 µs, the droplets are in optimal shape, and their size is about half the diameter of the nozzle. The experimental results validate the efficacy of this waveform design method, which combines numerical simulation and experiment, as well as demonstrating that ink droplet formation can be studied from the point of pressure variation at the nozzle.

Performance Analysis of CMOS Circuits using Shielded Channel Dual Gate Stack Silicon on Nothing Junctionless Transistor

In this paper it has been demonstrated that a shielded channel made by varying the side gate length in silicon-on-nothing junctionless transistor not only improves the short channel effect but also improve the performance of CMOS circuits of this device. The proposed device shielded channel dual gate stack silicon on nothing junctionless transistor (SCDGSSONJLT) drain induced barrier lowering (DIBL), cut-off frequency and subthreshold slope are improved by 20%, 39% and 20% respectively over the single material gate silicon on insulator junctionless transistor (SMG SOI JLT). The proposed device CMOS inverter fall time Tf (pS) and noise margin improves by 50% and 10% compare to shielded channel silicon on insulator junctionless transistor (SCSOIJLT). It has been observed that circuit simulation of CMOS inverter, NAND and NOR of proposed device. The static power dissipation in the case of proposed SCDGSSONJLT device are reduced by 45%, 81% and 83% respectively over the SMGSOIJLT. Thus, significant improvement in DIBL, cut-off frequency, propagation delay and static power dissipation at low power supply voltage shows that the proposed device is more suitable for low power CMOS circuits.

Lightning Impulse Long Delay Breakdown of Centimeter Vacuum Gaps

This paper presents an experimental investigation into the breakdown voltage fall time tf of lightning voltage breakdown of 2-4 centimeter vacuum gaps having a long breakdown delay time td(>30 μs). The results show that the average 50% breakdown voltage fall time t50 decreases with increasing vacuum gap. It is considered that the lightning impulse breakdown of the centimeter vacuum gaps with a long breakdown delay time may be initiated by the interaction between the cathode thermal processes and the micro-particles phenomena. The increase of the electrode diameter and the decrease of the electrode radius of curvature may contribute to the decrease of the breakdown voltage fall time.

Experimental study and mechanism of bistable all-optical switching based on diarylethene-doped film

A method for constructing bistable all-optical switching based on the changes in the photoinduced-absorption characteristics of diarylethene-doped organic films is proposed. A doped organic film sample (10 wt.% doping concentration) was prepared by doping cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene diarylethene into polymethyl methacrylate using a 375-nm continuous wave (CW) laser (40 mW) and 532-nm laser (CW, 5 mW) as the pump beam and a 632.8-nm laser (CW, 3 μW) as the probe beam. The experimental results of the bistable all-optical switching effect of the thin-film sample were obtained. The modulation depth M of the switching signal was 8.2 %, the rise time tr of the switching was approximately 36 s, and the falling time tf was approximately 47 s. The influence of the change in the pump beam power on the switching signal was studied experimentally. Based on the photochromic two-level system, a theoretical model of the bistable all-optical switching signal changing with time was established, the mechanism of bistable all-optical switching was clarified, and the experimental results were analyzed. The nonlinear fitting results show that the experimental data are in good agreement with the theoretical model. This bistable all-optical switching is simple and easy to implement, and it has potential application value as a low-speed bistable all-optical switching method.

Development of a Pulsed Power Supply Utilizing 13 kV Class SiC-MOSFETs

To resolve the drawback of conventional thyratron switches, development of a semiconductor high voltage switch utilizing a 13 kV class SiC-MOSFET developed by Tsukuba Power Electronics Constellations (TPEC) is proceeding. At first, the device evaluation test was carried out with a resistive load circuit. With the conditions of drain voltage of 10 kV and load resistance of 1 kΩ, turn on loss Eon, turn off loss Eoff, rise time Tr and fall time Tf were 1.7 mJ, 1.1 mJ, 64 ns, and 75 ns, respectively. Thereafter, the 2s-12p switch array was designed and assembled, where 12 MOSFETs are equally aligned on a circle shaped circuit board and two circuit boards are stacked in series. An 18 kV-318 A-1 us pulse with a rise time of 289 ns in the short pulse switching test were successfully demonstrated. Moreover, switching tests of 2nd generation MOSFET that has a twice larger device area was conducted. As a result, 60 % reduction of on-resistance was confirmed.

High Frequency Power Supply with 3.3 kV SiC-MOSFETs for Accelerator Application

Pulse switching characteristics of newly developed 3.3 kV SiC-MOSFET were investigated and they were provided for a prototype switching power supply (SPS). With supply voltage of 2.5 kV and the load resistor of 100 Ω, rise time Tr and fall time Tf were 76 ns and 88 ns respectively. The SPS exhibited a successful 2.5 kV-20 A-1 MHz burst mode operation.

A waveform design method for high DPI piezoelectric inkjet print-head based on numerical simulation

In order to increase the Dots Per Inch (DPI) of the piezoelectric inkjet print-head, the width and length of the pressure chamber have become much smaller. This makes some previous waveform design methods no longer suitable for the design of high DPI piezoelectric inkjet print-head. In this paper, a new waveform design method based on numerical simulation for high DPI print-head is proposed. Different parameters of the unipolar trapezoidal waveform were optimized using the multi-physics simulation software COMSOL to acquire the optimal waveform for good quality jetting. And meniscus motion at the nozzle exit was measured to predict the jetting behavior of print-head and verify the simulation results. When the high DPI print-head was actuated by the optimized waveform with the rising time tr = 3 µs, dwelling time td = 16 µs, and falling time tf = 3 µs, the high DPI piezoelectric inkjet print-head was continuous injection.

A high frequency and amplitude modulated CMOS laser diode driver for low noise readout applications

Laser diode driver (LDD) with high frequency modulation (HFM) output current is the key component for CD/DVD disk drive systems with low noise performance and better signal integrity during readout operation. The measured output current DC level can be up to 100 mA with oscillation frequency tunable from 150 to 660 MHz while the modulated amplitude up to 100 mA peak to peak, respectively. The current switching parameters about rising time tr is measured as 0.64 ns whereas the falling time tf as 0.58 ns. Besides, the activated or disable of built in HFM circuitry can be controlled through control signal. The novel LDD has been simulated and fabricated using TSMC 5 V 0.35 μm CMOS technology with overall chip size of 0.783 mm2. Experimental results have successfully proven the characteristics of this design and exhibited the capability to satisfy the wide tunable oscillated frequency and modulated swing which is suitable for low noise requirement of CD/DVD-Dual/RAM read mode operation.

(Invited) Characteristics of a Wire-Bonding-Less SiC Power Module Operating in a Wide Temperature Range

Introduction Using high-speed switching, wide bandgap semiconductor devices can reduce on-resistance in the on-state to realize low power converter losses. In addition, SiC power devices can be operated in high temperatures; thus, their cooling systems can be reduced in size or removed all together, thereby increasing the power density of the power converter. In this study, we designed and fabricated a SiC power module with a built-in snubber circuit. This power module is operable in high temperatures over 200 degrees C. Design of Power Module for High-Temperature Operation The manufactured power module, its components, and its circuit diagram are shown in Fig. 1. The module size is 30 × 44 × 29 mm3. Active metal brazing copper (AMC) substrates sandwich the four SiC-metal–oxide–semiconductor field-effect transistors (MOSFETs) in this structure. Two AMC substrates connect via the metal block. The C–R snubber circuit is built-in on the surface of AMC1 (Fig. 1(b)). The SiC-MOSFET and AMC1 are joined by a flip-chip-bonding technique using an Al bump. The others are joined by Au–Ge solder. Fig. 2 shows the 50-kHz switching waveforms. Fig. 3 shows the circuit configuration for the Fig. 2 waveforms. This power module can realize high-speed switching in a fall time tf @ 25 ns. Surge voltage and ringing are suppressed by the built-in snubber circuit. Acknowledgment This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation power electronics/Consistent R&D of next-generation SiC power electronics", and "the Novel Semiconductor Power Electronics Project Realizing Low Carbon Emission Society" (funding agency: NEDO). Figure 1

Shape Properties of Pulses Described by Double Exponential Function and Its Modified Forms

Double exponential function and its modified forms are widely used in high-power electromagnetics such as high-altitude electromagnetic pulse and ultrawide-band pulse study. Physical parameters of the pulse, typically the rise time t r , full width at half maximum t w , and/or fall time t f , usually need to be transformed into mathematical characteristic parameters of the functions, commonly denoted as α and β. This paper discusses the dependences of pulse shape properties, represented by ratios of t w / t r and t f / t r , on a dimensionless parameter A = β/α or B = α/β; and focuses on their limit correlations associated with the mathematical forms. It has been proven that pulses with t w / t r <; 4.29 cannot be expressed by the commonly used difference of double exponentials function. This limit can be mitigated partially by the latest proposed p-power of double exponentials function with a well-chosen p parameter. A novel form, difference of double Gaussian functions is also proposed to describe pulses with low t w / t r ratios better. Quotient of double exponentials, however, is shown to be the most flexible function for describing transient pulses with arbitrary t w / t r ratios, despite of its intrinsic drawbacks. All these functions are applied for several examples and further compared in both time and frequency domains.

Response of oscillation-controlled magnetic sensing

In the oscillation-controlled magnetic sensing system, the dependence of the response on the gain of the feedback loop and the oscillation frequency is investigated. Two types of response were observed according to the gain of the feedback loop. In the first response type, referred to herein as type A, the oscillation starts when the oscillation condition is satisfied and stops when the oscillation condition is not satisfied. In the second response type, referred to herein as type B, when the magnetic field changes, the oscillation starts and then stops because the oscillation condition was at the limit of being fulfilled. For an oscillation frequency of 31MHz, the rise time tR and the fall time tF were 179ns and 1.27μs, respectively, for the type-B response. These times were approximately 1∕10 of those observed for the type-A response. The linearity of the oscillation frequency and the response time in both logarithms was observed for the type-B response, and the rise time tR and fall time tF were reduced as the oscillation frequency was increased.

Double-interdigitated (TIL) bipolar transistor with heavily doped base wells

The letter reports the development of two interdigitation level (TIL) bipolar transistors with heavily-doped base wells (BW), having the following advantages in comparison with identical conventional devices: (a) an ∼18% and ∼23% increase of voltages VCEO(SUS) and VCBO, respectively; (b) a reduction of the turn-on delay (td)and rise (tr) times by a factor of ∼20; (c) a two-fold decrease of the fall time tf.

An ultra‐high‐voltage high‐speed switching power transistor with new fine emitter structure

AbstractAlong with the trend toward smaller size and lower energy consumption in electronic equipment, the dc stabilized power supply has been changed from the series dropping to the switching version, which tan he made more compact and light with high efficiency. the switching frequency in these efforts has increased with each year.Component parts are required for performance in higher frequency regions and it is also hoped that switching transistors will be improved in terms of high speed and large safe operating area. High‐speed switching and large safe operating area have hitherto progressed in a trade‐off relation. This was overcome by decreasing the base resistance via S‐parameter analysis. A newly developed fine emitter structure and oxide planar structure have led to creation of an excellent switching power transistor possessing ultra‐high voltage (1200 V), high‐speed switching characteristics (rise time tr = 200 ns, storage time tstg 2500 nsec, fall time tf = 70 nsec), and large safe operating area (secondary breakdown onset current Isb = 8 A, collector * emitter clamp voltage VCEX(clamp) = 90 V).