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
Q. Determine the voltages V x using voltage division and equivalent resistor reductions for the circuits shown in Figure.

Short-Term Measures for Technical Loss Reduction The short-term measures involve measures needs for immediate improvement and reduction of losses within the system. These are

Code, Stack, Data, Extra Segment registers in 8086.

what is inductor

Second Generation ( 1954- 1964) After the invention of semiconductor devices mainly transistors size of computer s was reduced a lot computing power increased reliability was

What are the blocks of the microprocessor depends system? The blocks of the microprocessor depends system are: The Memory and I/O System The Data Operating System

Mention how do the NEG & NOT instructions differ in their functionality Here, NOT: The one's complement or logical inversion NEG: The two's complement or arith

Explain the different instruction formats with examples The instruction set is grouped into the following formats One byte instruction MOV C,A Two byte instruction

1. Suppose the California government sets aside a square patch of land that is 10 kilometers on each side and plans to use this land to generate electrical power with wind turbines

Carry Fla Registers  The  size  of the accumulator is of 8 bit  if after  any arithmetical  or logical  operation 9 th   bit is generated i e  there is  carry beyond  D 7   bi