Gyaan Series

JUNCTION FIELD EFFECT TRANSISTOR The JFET is abbreviated as Junction Field Effect Transistor. JFET is just like a normal FET. The types of JFET are n-channel FET and P-channel FET. A p-type material is added to the n-type substrate in n-channel FET, whereas an n-type material is added to the ptype substrate in p-channel FET. Hence it is enough to discuss one type of FET to understand both. N-Channel FET: The N-channel FET is the mostly used Field Effect Transistor. For the fabrication of Nchannel FET, a narrow bar of N-type semiconductor is taken on which P-type material is formed by diffusion on the opposite sides. These two sides are joined to draw a single connection for gate terminal. This can be understood from the following figure.  These two gate depositions (p-type materials) form two PN diodes. The area between gates is called as a channel. The majority carriers pass through this channel. Hence the cross sectional form of the FET is understood as the following

FIELD EFFECT TRANSISTOR A  FET is a three-terminal unipolar semiconductor device . It is a voltage controlled device unlike a bipolar junction transistor. The main advantage of FET is that it has a very high input impedance, which is in the order of Mega Ohms. It has many advantages like low power consumption, low heat dissipation and FETs are highly efficient devices. The following image shows how a practical FET looks like.  The FET is a unipolar device, which means that it is made using either p-type or n-type material as main substrate. Hence the current conduction of a FET is done by either electrons or holes. Features of FET: The following are the varied features of a Field Effect Transistor. . Unipolar − It is unipolar as either holes or electrons are responsible for conduction. . High input impedance − The input current in a FET flows due to the reverse bias. Hence it has high input impedance. . Voltage controlled device − As the output voltage of a FET is co