![]() ![]() It is also feasible to make P-channel IGBTs and for which the doping profile in each layer will be reversed. ![]() The N+ layer at the top is the source or emitter and the P+ layer at the bottom is the drain or collector. It shares similar MOS gate structure and P wells with N+ source regions. It is evident that the silicon cross-section of an IGBT is almost identical to that of a vertical Power MOSFET except for the P+ injecting layer. This is one of several structures possible for this device. The basic schematic of a typical N-channel IGBT based upon the DMOS process is shown in Figure 1. It also has excellent forward and reverse blocking capabilities. It has superior current conduction capability compared with the bipolar transistor. It canbe easily controlled as compared to current controlled devices (thyristor, BJT) in high voltage and high current applications. Low driving power and a simple drive circuit due to the input MOS gate structure.So smaller chip size is possible and the cost can be reduced. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density.The main advantages of IGBT over a Power MOSFET and a BJT are: Optimized IGBT is available for both low conduction loss and low switching loss. It is equally suitable in resonant-mode converter circuits. IGBT improves dynamic performance and efficiency and reduced the level of audible noise. It also can be used in Uninterruptible Power Supplies (UPS), Switched-Mode Power Supplies (SMPS), and other power circuits requiring high switch repetition rates. The IGBT is suitable for many applications in power electronics, especially in Pulse Width Modulated (PWM) servo and three-phase drives requiring high dynamic range control and low noise. It combines the best attributes of both to achieve optimal device characteristics. It’s a functional integration of Power MOSFET and BJT devices in monolithic form. To make use of the advantages of both Power MOSFET and BJT, the IGBT has been introduced. Many designers view IGBT as a device with MOS input characteristics and bipolar output characteristic that is a voltage-controlled bipolar device. The Insulated Gate Bipolar Transistor (IGBT) is a minority-carrier device with high input impedance and large bipolar current-carrying capability. ![]()
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