Rise time

About: Rise time is a research topic. Over the lifetime, 4748 publications have been published within this topic receiving 47512 citations.

Inaccurate Switching Loss Measurement of SiC MOSFET Caused by Probes: Modelization, Characterization, and Validation

Abstract: SiC metal–oxide–semiconductor field-effect transistor (MOSFET) has a fast switching speed and high slew rate. However, its ultrashort switching time approximates the rise time and propagation delay of the measurement instruments, which results in an inaccurate assessment of the switching loss and challenges the thermal design of the power converter. In this article, aiming to reveal the principles of accurate measurement for the switching behavior of SiC MOSFET, insightful models are proposed for baseline probes and transient trajectories to characterize the measurement error of the switching losses. By using the Gaussian function, the mathematical models for the rise time, bandwidth, and propagation delay of the measurement instruments are achieved, which is also confirmed by the surveyed specifications of commercial probes. Concerning the accurate measurement, the turn-on and turn-off losses of the SiC MOSFET influenced by the rise time and propagation delay of probes are comprehensively modeled and characterized. With respect to different current probes, voltage probes, and gate driver resistances, extensive experiments are demonstrated to confirm the validity of the proposed models. The experimental findings are in line with the conducted predictions of the proposed models. It is found that, due to the very fast switching transients of the SiC MOSFET, the limited bandwidth and inevitable propagation delay of measurement instrument may result in a prominent error of the switching loss and impede the widespread implementation of the SiC MOSFET.

The design and operation of a compact high-voltage, high pulse repetition frequency trigger generator

Abstract: A high-voltage trigger generator has been developed to trigger an in-line plasma closing transfer switch. The trigger generator is capable of producing 70 kV voltage pulses, having a rise time and duration of 10 and 60 ns respectively. It uses a stacked Blumlein cable generator fired using a triggered corona stabilized (TCS) switch and is fully controllable in frequency from single shot up to 10 kHz in a burst mode. The device is very compact, portable and is operated via a fibre optic link from a solid state pulse generator. The trigger generator can also be used as a fast high-voltage, high peak power and high-frequency driving device.

Traveling-Wave Marx Circuit for Generating Repetitive Sub-Nanosecond Pulses

Abstract: The traveling-wave Marx generator was first proposed by Carl Baum to analyze the switch-closure propagation process in fast pulsed-power systems. To improve the performance of the transistorized sub-nanosecond pulse generator, the traveling-wave Marx circuit with inter-stage transmission lines is studied. Simulations indicate that the delay time and the impedance of inter-stage transmission lines [microstrip lines on printed circuit board (PCB)] are main factors affecting the pulse waveform. Based on it, the series connection of modularized Marx circuits is proposed, which has the advantages of adjustable amplitude and bendable circuit layout. A compact high-amplitude pulse generator is developed with the amplitude of 8.2 kV, the rise time of 150 ps, and the PCB length of 35 cm. For higher pulse repetition rate, the heat dissipation design of PCB is necessary; however, due to the variations in the microstrip line structure, the commonly used metallic heat sink may cause a significant decrease in pulse amplitude. Thus, a novel heat dissipation design is proposed by optimizing the layout of metallic sinks and introducing heat-conducting ceramic sinks. A high-repetition-rate pulse generator is developed with the maximum pulse repetition rate of 600 kHz, the amplitude of 1.1 kV, and the rise time of 160 ps.

Memory circuit with increased operating speed

Abstract: Digit lines, connected to the input and output terminals of a memory cell composed of MISFETs, are coupled to common data lines through a switching circuit which is controlled by a decoder circuit. There is also connected with the digit lines a load which is composed of a plurality of enhancement mode MISFETs connected in series in the diode form. The high level of the signals at the digit lines is lowered by the action of the load means. In response to the reduction in the potentials at the digit lines, the switching means is rendered conductive at an early rise time of control signals. As a result, the operating speed of the memory circuit can be increased.

X-ray radiation from the volume discharge in atmospheric-pressure air

Abstract: X-ray radiation from the volume discharge in atmospheric-pressure air is studied under the conditions when the voltage pulse rise time varies from 0.5 to 100 ns and the open-circuit voltage amplitude of the generator varies from 20 to 750 kV. It is shown that a volume discharge from a needle-like cathode forms at a relatively wide voltage pulse (to ≈60 ns in this work). The volume character of the discharge is due to preionization by fast electrons, which arise when the electric field concentrates at the cathode and in the discharge gap. As the voltage pulse rise time grows, X-ray radiation comes largely from the discharge gap in accordance with previous experiments. Propagation of fast avalanche electrons in nitrogen subjected to a nonuniform unsteady electric field is simulated. It is demonstrated that the amount of hard X-ray photons grows not only with increasing voltage amplitude but also with shortening pulse rise time.