Driving a new monolithic cascode device in a DC-DC converter application

In this paper, a case study application of a new device, which is based on a bipolar-MOSFET cascode connection, is presented. The monolithic device can be designed for high-voltage applications up to 1.7-2.2 kV. The basic features of this power device are described in terms of the physical structure and the electrical performance. An application in the field of dc-dc converters is presented, and the drive unit requirements are investigated and discussed through several circuit topologies that are devoted to energizing the four-terminal device. The advantages and the drawbacks of the device are compared with those of a MOSFET in terms of the switching losses and the command circuitry. The correlation between the physical structure of the cascode and its electrical characteristics is explained to better understand some interesting features of the device. Last, the new device is tested by using a forward converter as a workbench to provide converter designers with useful guidelines concerning the switching behavior and the power losses. Index Terms--Bipolar junction transistor (BJT), cascode, forward converter, metal-oxide-semiconductor field-effect transistor (MOSFET).