fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
Saturation region(on) and Cut off region(off).
FET
Remains constant
5v
A FET (Field Effect Transistor) is mainly used when the input signal needs to be isolated from the output. A FET has a very high input resistance, so very little current is required from the input. Voltage gain is not the main objective when using a FET.
Cutoff voltage is the point at which the battery is fully discharged. This is usually the point at which the device will shut itself off.
in BJT forwardbiasing & reverse biasing are carried out but in FET voltage divider biasing &self biasing are carried out.
Cutoff voltage is the point at which the battery is fully discharged. This is usually the point at which the device will shut itself off.
A Field Effect Transistor is a device with a single channel (conductor between two of the terminals). This channel is turned on an off by a voltage applied to the third terminal which is connected to the conducting channel in a J fet (junction Fet) or isolated from the channel in a Metal Oxide Semiconductor (MOS) fet. To keep the explanation simple, an enhacement mode MOS FET pulls charge carriers (electrons for N channel and holes for P channel) into the channel so its resistance decreases. This turns it on. By removing this voltage, charge carries move out of the channel and the FET turns off. It can be turned on partially by putting a small voltage on the control terminal called the GATE. In an N channel FET, the charge carriers (electrons) move from the SOURCE terminal (-ve) to the DRAIN terminal (+ve) when the FET is on. The voltage on the GATE is applied with respect to the SOURCE. In a P channel enhancement mode FET, charge carriers (holes) are also pulled into the channel in the same way but because the charge carriers are holes, the SOURCE is the +ve terminal and the DRAIN is the negative. The holes referred to are gaps in the crystal lattice of a substance like silicon which is doped (impurities added) with aluminum which has only 3 electrons in the outer shell instead of 4 like silicon. In a depletion mode FET, everything is the same except in reverse. Charge carriers are pushed OUT of the conducting channel.
since in an FET the value of the current depends upon the value of the voltage applied at the gate and drain...so it is known as voltage controlled device.. for example..in a mosfet..the current from drain to source depends upon the width of the depletion layer..which in turn depends upon the voltage applied on the gate.. so that is the reason
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