The additional silicon oxide insulator reduces the capacitance of the gate which makes it vulnerable against the very high voltage spikes inevitably damaging the internal components. MOSFETs are more susceptible to electrostatic discharge (ESD) as high input impedance of MOS technology in a MOSFET won’t allow the charge to dissipate in a more controlled fashion. It efficiently blocks the applied voltage with the exception of a small leakage current. The layer is made of silicon oxide which is one of the best insulators used. MOSFETs require almost no input current to control the load current which makes them more resistive at the gate terminal, thanks to the isolation layer between the gate and the channel. They can be easy to control as compared to current controlled devices in high current applications. A MOSFET can function in two ways: Depletion mode and Enhancement mode.Īn IGBT is a voltage-controlled bipolar device with high input impedance and large current-handling capability of a bipolar transistor. MOSFET generally works by electronically varying the width of the channel by the voltage on an electrode called the gate which is located between the source and the drain, and is insulated by a thin layer of silicon oxide.

MOSFET is a special type of field-effect transistor in which the applied voltage determines the conductivity of a device.Īn IGBT is essentially a MOSFET device that controls a bipolar junction power transistor with both transistors integrated on a single piece of silicon, whereas MOSFET is the most common insulated gate FET, most commonly fabricated by the controlled oxidation of silicon. IGBTs are gatekeepers of current that combine the advantages of a BJT and MOSFET for use in power supply and motor control circuits. Although, both are voltage-controlled semiconductor devices that work best in switch mode power supply (SMPS) applications, IGBTs combine the high-current handling capability of bipolar transistors with the ease of control of MOSFETs. IGBT stands for Insulated-Gate Bipolar Transistor, whereas MOSFET is short for Metal-Oxide Semiconductor Field Effect Transistor. Its structure is almost identical to that of a MOSFET except the additional of a p substrate beneath the n substrate. They are a relatively new device in power electronics typically used as an electronic switch in a wide a range of applications, from medium to ultra high power applications such as switched mode power supplies (SMPS).

IGBT, stands for “Insulated Gate Bipolar Transistor”, is a three-terminal semiconductor device which combines the current-carrying capability of a bipolar transistor with the ease of control of that of a MOSFET. The technology is now used in all kinds of semiconductor devices to amplify weak signals. The gate is located between the source and drain and is insulated by a thin layer of metal oxide which prevents the current from flowing between the gate and the channel. It’s a four-terminal semiconductor device that controls both analog and digital signals. MOSFET, short for “Metal Oxide Semiconductor Field Effect Transistor”, is a special type of field effect transistor widely used in very large scale integrated circuits, thanks to its sophisticated structure and high input impedance. This article highlights some key points comparing the two devices. The IGBT is basically a cross between the bipolar transistors and MOSFETs and is also voltage-controlled like MOSFETs. Then, IGBTs came into the picture in the late 1980s. They have positive temperature coefficient for resistance that stops thermal runaway and as a result secondary breakdown does not occur. MOSFETs, however, are devices that are voltage controlled rather than current-controlled. The bipolar transistors have relatively slow turn-off characteristics and they exhibit negative temperature coefficient which may result in secondary breakdown. The BJTs have gone through vital enhancements of its electrical performance since its inception in late 1947 and is still widely used in electronic circuits. The bipolar transistors were the only real power transistor used until the very efficient MOSFETs came along in the early 1970’s.

Transistor vs mosfet