Cesare Ronsisvalle

A new monolithic emitter-switching bipolar transistor (ESBT) in high-voltage converter applications

In this paper a new family of devices, which is based on a bipolar-MOSFET cascode connection, is presented. The monolithic device is suitable for high-voltage applications. The basic features of this power device, the emitter-switching bipolar transistor (ESBT) component, are described both in terms of physical structure and electrical performances. The field of applications along with the driver requirement is discussed too. The advantages and drawbacks of the presented device in terms of both switching losses and base-gate command circuitry are compared with those of a MOSFET. Finally, the new device is tested by using as a workbench an actual off-line power supply (forward converter), in order to carry out useful information for the power converter designer about the switching behavior and the power losses.

Different designs for the optimization of monolithic ESBT(Emitter-Switched Bipolar Transistor)

This study is aimed to improve the electrical performance (both on-resistance and current capability) of the novel power actuator by varying its horizontal geometry. As a matter of fact the topology of the elementary cell of ESBTreg has the peculiarity that the MOSFET cells are drawn inside the emitter fingers of the bjt side: this in order to achieve the monolithical solution of cascode connection between an high voltage bjt and a low voltage MOSFET. The object of this study is the one to discover which is the best trade-off between the perimeter of the emitter finger of the bjt part and the perimeter of the channel of the MOSFET part

ESBT® power switch in high-power high-voltage converters

Recently available on the market the emitter switched bipolar transistor (ESBT) having high voltage breakdown, low voltage drop, and low switching losses as well, represents an interesting alternative to other power transistors thus giving a new chance to further improve the system efficiency. This paper deals with a new silicon technology used to produce a high voltage monolithic cascode and gives a way to drive the new device in low range power Applications (>lkW). Special focus has been dedicated to inverters and a perspective on the device use in DC/DC converters is given. The loss cutting allows either a strong equipment size reduction or a higher power while maintaining the size.

Improvement of high-voltage junction termination extension (JTE) by an optimized profile of lateral doping (VLD)

The planar edge termination technique of junction termination extension (JTE) was investigated and optimized by using a two-dimensional device simulator. Particular attention was paid to achieve the least electrical field at the silicon/oxide interface of JTE region in order to decrease the surface charges sensitivity and then the reliability of the structure.

A new version of monolithic ESBT® power actuator with increased current capability

A simple trick in the device design has permitted to sensibly increase the current capability of ESBT devices. This improvement was obtained without altering neither the design rules, nor the diffusion process, but with a different shape of the base contact. This paper explains some points of the device physics with the help of 3D electrical simulations. As a matter of fact the simulations showed the presence of a lateral parasitic diode that can be inhibited by a proper layout design. The electrical measurements of the new packaged devices have fully confirmed the predictions of the simulations.

Theoretical study about the RBSOA of a monolithic ESBT ® (emitter-switched bipolar transistor) versus the saturation level before the switching-off

One of the main strength points of the new power actuator emitter-switched bipolar transistor (ESBT^(R)) is its excellent safe operating area: as a matter of fact the emitter-switching concept enables the driving of the bipolar transistor in a much safer way compared to the traditional base-switching one. Nevertheless, at very high current density, well above the working ones, its ruggedness decreases a little when the saturation level, just before the turn-off, is extremely low or extremely high. This paper explains that in these conditions the device switches off not exactly in emitter-switching conditions or it is not properly sized.

Optimal Design of Monolithic ESBT Device carried out by Multiobjective Optimization

This work concerns the multiobjective optimization of an monolithic ESBT_ device aimed to get a characterization of the best design. The optimization will select the epitaxial specifications (thickness, doping concentration) which minimize the energy dissipation, maximize the current flow and keep a breakdown voltage of 1000V. Since these goals are in conflict with each other the best solution must be characterized with respect to all trade-offs. The search was carried out with an extension of the DIRECT algorithm to the multiobjective case.