Phenomenon - fet operation, Electrical Engineering

Phenomenon - Fet operation:

For either improvement- or depletion-mode devices, at drain-to-source voltages very much less than gate-to-source voltages, changing the gate voltage will change the channel resistance, drain current will be proportional to drain voltage (referenced to source voltage). In this type of mode the FET operates such as a variable resistor and the FET is said to be operating in a linear modeor ohmic mode.

If drain-to-source voltage is gets increased, this creates a important asymmetrical change in the shape of the channel because of a gradient of voltage potential from source to drain. The shape of the inversion region turns "pinched-off" near the drain end of the channel. If drain-to-source voltage is raised further, the pinch-off point of the channel starts to move away from the drain in the direction of the source. The FET is supposed to be in saturation mode; a number of authors refer to it as active mode, for a better analogy along with bipolar transistor operating regions. The saturation mode, or the region in between the ohmic and saturation, is employed while amplification is required. The in-between region is occasionally considered to be part of the ohmic or linear region, even in which drain current is not approximately linear with drain voltage.

Although the conductive channel made by gate-to-source voltage no longer connects source to drain throughout saturation mode, from flowing the carriers are not blocked. Considering once again an n-channel device, a depletion region available in the p-type body that surrounding the conductive channel and drain and source regions. The electrons that have the channel are free to move out of the channel by the depletion region if attracted to the drain through drain-to-source voltage. The carriers' depletion region is free and comprises a resistance identical to silicon. Any type of rise of the drain-to-source voltage will increase the distance from drain to the pinch-off point, increasing resistance because of the depletion region proportionally to the applied drain-to-source voltage. This proportional change results in the drain-to-source current to remain comparatively fixed independent of changes to the drain-to-source voltage and quite different the linear mode operation. So in saturation mode, the FET acts like a constant-current source rather than like a resistor and can be used most efficiently as a voltage amplifier. In this type of case, the gate-to-source voltage ascertains the level of constant current by the channel.

Posted Date: 1/11/2013 4:50:02 AM | Location : United States







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

Write discussion on Phenomenon - fet operation
Your posts are moderated
Related Questions
A 100-kW, 230-V shunt generator has R a = 0.05  and R f = 57.5 . If the generator operates at rated voltage, calculate the induced voltage at (a) full load, and (b) one-half fu

Q. The line-to-line voltage of a balanced wye connected three-phase source is given as 100 V. Choose V AB as the reference. (a) For the phase sequence A-B-C, sketch the phasor

Give the properties and application of glass. Glass - It is an inorganic material made by the fusion of various metallic oxides. The properties of glass are as - Glass is


Q. Input bias current of operational amplifier? When operated at extremely low quiescent current values, the base bias currents will be low; but they do have to be taken into c

Hi, I need help simulating my project in Proteus, problem is, I have never used it before. This is what I have so far. However, feel free to suggest ideas that will make the circ

Explain graphics adapters. Video card converts digital output by the computer in an analog video signal and sends the signal by a cable to the monitor also termed as a graphic

Explain cascading of multiple PICS 8259.  The 8259A adds 8 vectored priority encoded interrupts to the microprocessor. It can be expanded to 64 interrupt requests by using one

Q.  A shunt generator gives full load output of 30 kW at a terminal voltage of 200V. The armature and field resistance are 0.05? and 50? resp.. The iron and friction losses are 10

Q. Explain Current and Magnetic Force? The rate ofmovement of net positive charge per unit of time through a cross section of a conductor is known as current, i(t) = dq / dt