Trench insulated gate bipolar transistor - a high power switching device

This paper presents a comprehensive theoretical study of the Trench Insulated Gate Bipolar Transistors (TIGBT). Specific physical and geometrical effects, such as the accumulation layer injection, increased channel density, increased channel charge and transversal electric field modulation are discussed. The potential advantages of the Trench IGBT over its conventional planar variant are highlighted. It is concluded that the Trench IGBT is one of the most promising structures in the area of high voltage MOS-controllable switching devices.

Dead-time minimisation using active voltage control gate drive for high-power IGBT converters

High-power converters usually need longer dead-times than their lower-power counterparts and a lower switching frequency. Also due to the complicated assembly layout and severe variations in parasitics, in practice the conventional dead-time specific adjustment or compensation for high-power converters is less effective, and usually this process is time-consuming and bespoke. For general applications, minimising or eliminating dead-time in the gate drive technology is a desirable solution. With the growing acceptance of power electronics building blocks (PEBB) and intelligent power modules (IPM), gate drives with intelligent functions are in demand. Smart functions including dead time elimination/minimisation can improve modularity, flexibility and reliability. In this paper, a dead-time minimisation using Active Voltage Control (AVC) gate drive is presented. © 2012 IEEE.

SuperJunction IGBTS: An evolutionary step of silicon power devices with high impact potential

15 years ago the vertical SuperJunction (SJ) concept conceived for SJ power MOSFETs was the last, major breakthrough in the field of silicon power devices. Today, the SuperJunction MOSFET technologies have reached a mature stage characterized by gradual performance improvements. SuperJunction Insulated Gate Bipolar Transistors (SJ IGBTs) could interrupt this stagnation holding promise to revitalize voltage classes from 600 up to 1200 V. Such SJ IGBTs surpass by a very significant margin their SJ MOSFET counterparts both in terms of power handling capability, on-state and turn-off losses, all at the same time. On the higher end of the voltage class, SJ IGBTs would top the performance of 1.2 kV IGBTs by a similar margin. © 2012 IEEE.

Theory of high-power mode-locked lasers with a slow absorber

We develop an analytical theory of high-power passively mode-locked lasers with a slow absorber; the theory is valid at pulse energies well exceeding the saturation energy. We analyze the Haus modelocking master equation in the pulse-energy-domain representation, approximating the intensity profile function by a series in the vicinity of its peak value. We consider the high-power operation regime of subpicosecond blue-violet GaN mode-locked diode lasers, using the approach developed. © 2010 Springer Science+Business Media, Inc.

High power, low-jitter encoded picosecond pulse generation using an rf-locked self-q-switched multicontact GaAs/GaAlAs diode laser

The RF locking of a self-Q-switching diode laser is shown to reduce the jitter of a 2.48 GHz train of 1 W peak power picosecond pulses to less than 300 fs. By using direct modulation of the loss in the Q-switched laser, direct encoding of data has been achieved at rates in excess of 2 Gbit/s.

Narrow line high power picosecond pulse generation in a multicontact distributed feedback laser using modified Q switching

High power bandwidth-limited picosecond pulses with peak powers in excess of 200 mW have been generated using multi-contact distributed feedback laser diodes for the first time. The pulses have widths typically less than 10 ps, time-bandwidth products of as little as 0·24, and can be generated on demand at generator limited repetition rates of up to 140 MHz.

A high temperature and low power SOI CMOS MEMS based thermal conductivity gas sensor

The design, 3D FEM modelling and measurement results of a novel high temperature, low power SOI CMOS MEMS thermal conductivity gas sensor are presented here. The sensor consists of a circular membrane with an embedded tungsten micro-heater. The high sensing capability is based on the temperature sensitivity of the resistive heating element. The sensor was fabricated at a commercial foundry using a 1 μm process and measures only 1×1 mm 2. The circular membrane has a 600 μm diameter while the heating element has a 320 μm diameter. Measurement results show that for a constant power consumption of 75 mW the heater temperature was 562.4°C in air, 565.9°C in N2, 592.5°C for 1 % H2 in Ar and 599.5°C in Ar. © 2013 IEEE.

Comparative analysis of static and switching performance of 1.2 kV commercial SiC transistors for high power density applications

This paper presents a critical comparison of static and switching performance of commercially available 1.2 kV SiC BJTs, MOSFETs and JFETs with 1.2 kV Si IGBTs. The experiments conducted are mainly focussed on investigating the temperature dependence of device performance. As an emerging commercial device, special emphasis is placed on SiC BJTs. The experimental data indicate that the SiC BJTs have relatively smaller conduction, off-state and turn-off switching losses, in comparison to the other devices. Furthermore, SiC BJTs have demonstrated much higher static current gain values in comparison to their silicon counterparts, thereby minimising driver losses. Based on the results, the suitability of SiC devices for high power density applications has been discussed. © 2013 IEEE.

Predictive optimisation of high-power IGBT switching under Active Voltage Control

Active Voltage Control (AVC) is an implementation of classic Proportional-Derivative (PD) control and multi-loop feedback control to force IGBT to follow a pre-set switching trajectory. The initial objective of AVC was mainly to synchronise the switching of IGBTs connected in series so as to realise voltage balancing between devices. For a single IGBT switching, the AVC reference needs further optimisation. Thus, a predictive manner of AVC reference generation is required to cope with the nonlinear IGBT switching parameters while performing low loss switching. In this paper, an improved AVC structure is adopted along with a revised reference which accommodates the IGBT nonlinearity during switching and is predictive based on current being switched. Experimental and simulation results show that close control of a single IGBT switching is realised. It is concluded that good performance can be obtained, but the proposed method needs careful stability analysis for parameter choice. © 2013 IEEE.

High-power ultrafast solid-state laser using graphene based saturable absorber

We demonstrate a graphene based saturable absorber mode-locked Nd:YVO4 solid-state laser, generating ~14nJ pulses with ~1W average output power. This shows the potential for high-power pulse generation. © 2011 Optical Society of America.

High-power ultrafast solid-state laser using graphene based saturable absorber

We demonstrate a graphene based saturable absorber mode-locked Nd:YVO4 solid-state laser, generating ~14nJ pulses with ~1W average output power. This shows the potential for high-power pulse generation. © 2011 Optical Society of America.

High-power ultrafast solid-state laser using graphene based saturable absorber

We demonstrate a graphene based saturable absorber mode-locked Nd:YVO4 solid-state laser, generating ~14nJ pulses with ~1W average output power. This shows the potential for high-power pulse generation. © 2011 Optical Society of America.