IGBTs (Insulated Gate Bipolar Transistors) combine the simplicity of drive and the excellent fastswitching capability of the MOSFET structure with the ability to handle high current values typical of abipolar device. IGBTs also offer good behavior in terms of voltage drop. IGBT technology, developed inthe early 1980s, has quickly gained market share for applications exceeding 400V and that work up to130kHz. This paper includes a brief description of the structure and the physics of the device, followed byan analysis of the principal static and dynamic characteristics. Further details about the behavior inoperation will also be analyzed and discussed in order to give a complete overview of the mainparameters, features, and static and dynamic behaviors of this power component.2. IGBT STRUCTURE AND OPERATION.Figure 1: IGBT Structure And Equivalent SchematicIGBTs are a natural evolution of the vertical Power MOSFETs for high current, high voltage applicationsand fast end-equipment. This device eliminates the main disadvantage of current high voltage powerMOSFETs characterized by an high value of RDS(on) caused by the high resistivity of the source-drainpath necessary to obtain a high breakdown voltage BVDSS. The power conduction losses at high currentlevels are considerably less in IGBT technology even when compared with the latest generation of PowerMOSFET devices that have been greatly improved in terms of RDS(on). The lower voltage drop,ALUMINUM GATEEMITTERPOLYSILICONN+ N+ N+ N+P+ P+N-N+P+ SUBSTRATE J1J2J3COLLECTORCGEDecember 2001 1/16AN1491APPLICATION NOTEIGBT BASICS M. Aleo (mario.aleo@st.com)AN1491 - APPLICATION NOTE2/16translated into a low VCE(sat), together with the device’s structure allow a higher current density than astandard bipolar device simplifying the IGBTs driver schematic as well. The vertical section depicted infigure 1 together with the equivalent circuit shows IGBTs basic structure.
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