Fet operation, Electrical Engineering

FET operation:

1585_FET operation.png

Figure: I-V characteristics and output plot of a JFET n-channel transistor.

The FET manages the flow of electrons (or electron holes) from the source to drain by influencing the size and shape of a "conductive channel" created and affected by voltage (or lack of voltage) applied across the gate and source terminals (For easiness of discussion, this assumes body and source are related). This conductive channel is the "stream" by which electrons flow to drain from source.

A negative gate-to-source voltage causes a depletion region to expand in width and encroach on the channel from the sides, narrowing the channel, in an n-channel depletion-mode device. If the depletion region expands to fully close to channel, the resistance of the channel from source to drain turns large, and the FET is efficiently turned off like a switch. Similarly a positive gate-to-source voltage raises the channel size and permits electrons to flow easily.

On the other hand, in an n-channel enhancement-mode device, a positive gate-to-source voltage is essential to create a conductive channel, because one does not exist naturally within the transistor. The positive voltage that is attracts free-floating electrons within the body towards the gate, creating a conductive channel. But first, sufficient electrons must be attracted near the gate to counter the dopant ions added to the body of the FET; this makes a region free of mobile carriers called a depletion region, and the phenomenon is considered to as the threshold voltage of the FET. Further gate-to-source voltage rises will attract even much more electrons towards the gate that are able to create a conductive channel from source to drain; this process is termed as inversion.

Posted Date: 1/11/2013 4:48:47 AM | Location : United States







Related Discussions:- Fet operation, Assignment Help, Ask Question on Fet operation, Get Answer, Expert's Help, Fet operation Discussions

Write discussion on Fet operation
Your posts are moderated
Related Questions
Evaluate the form factor: For the saw tooth wave illustrated in Figure, find out the form factor. Figure: Saw Tooth Wave Solution Time period of given wave i

Explain the two types of materials that are formed after doping. Depending on the impurity added, extrinsic semiconductors can be then subdivided in two types of class: N-ty

Q.‘Pentium processor has a superscalar architecture'. Describe the meaning of statement. Ans:Pentium microprocessor is organized with three execution units. One executes float

Define NOT Gate - Microprocessor? The NOT GATE which is as well called an Inverter, is used to invert the logic state of a signal. The output Q is true while the input A is NOT

Ceramics are good (A)  Insulators.                 (B) Conductors. (C)  Superconductors.      (D) Semiconductors. Ans: Ceramics are good insulators.

Bronze is an alloy of (A) Copper and Tin.               (B) Copper and Steel. (C) Copper and Mercury.      (D) Copper and Aluminium. Ans: Bronze is an alloy of Cop

Calculation of Aggregate Technical and Commercial Loss The concept of AT&C loss was introduced within 2001-02. The AT&C losses are presently in the range of 18% to 62% in seve


Consider an electromagnet, as shown in Figure, which is used to support a solid piece of steel and is excited by a coil of N = 1000 turns carrying a current i = 1.5 A. The cross-se

fast decoupled program