MOSFET Vs

THE MOSFET TRANSISTOR

METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR

The power MOSFET transistor is an array of hundreds transistors integrated in a same silicon substrate. Each transistor drive a proportional part of total current.

The principal MOSFET development reason was the multiple limitations of the traditional Bipolar Junction Transistors.

Each manufacturer has development his own integration technology. MOSFET are known with the following brand names VMOS, UMOS, TMOS, HEXFET, referring with the first letter to the silicon integration geometry.

MOSFET's are voltage controlled devices, this means that drain current is function of gate voltage. The following figure is the transfer characteristic of a MOSFET transistor.

Transconductance, always crescent with drain current, has the responsibility of the MOSFET characteristic sound, the distortion harmonics components fall strongly beyond the second.

MOSFET's are extremely fast devices, because needs a very small gate current to saturate or release the channel charge. For this property MOSFET's are widely used in switching applications. MOSFET's faster characteristics permits to design power output stages with wide bandwith and gain with better sound.

MOSFET's has a very high input impedance, in consequence the driver stage is a low power circuit incrementing the global amplifier efficient. In other hand, the low power driver requires less transistors incrementing the free time between fails.

In high power designs MOSET's transistor can paralleling in order to drive more current. This configuration is very stable thermically.

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