Why fet is a voltage sensitive device, Electrical Engineering

Assignment Help:

Q. Why FET is a voltage sensitive device explain from the drain characteristics?

The JFET consists of a thin layer of n-type material with two ohmic contacts,the source S and the drain D ,along with two rectifying contacts ,called the gates G .If a positive voltage is placed between drain and source,electrons will flow from source to drain .This conducting path between the source and the drain is called a channel.

Consider holding the drain source voltage fixed and varying the gate-source voltage .As the gate-source voltage is made negative ,the gate channel  pn junction is   reverse biased ,increasing the depletion red\gion between the gate and source .This decreases the channel width ,increasing the channel resistance.if the drain-source voltage  VDS is kept constant   ,the current IDS  decreases .when the gate-source voltage  is  made positive,the depletion region decreases until,for large positive gate-source voltages ,the channel opens .then the pn- junction  between gate and channel  becomes  forward biased and current flows from the gate to the source current Summarizing we find that varying the gate voltage varies the channel width ,and hence the channel resistance  .This  inturn  varies the current from drain to source,IDS .We see that it is the gate-source voltage variation which varies IDS ; thus the FET is a voltage sensitive device ,compared with the junction transistor , which is a current sensitive device.


Related Discussions:- Why fet is a voltage sensitive device

Explain priority interrupts of 8085, Explain priority interrupts of 8085. ...

Explain priority interrupts of 8085. The 8085 microprocessor has five interrupt inputs. They are TRAP, RST .5, RST 6.5, RST 5.5, and INTR. These interrupts have a fixed prio

Zener breakdown voltage, (a) For the Zener diode series voltage regulator s...

(a) For the Zener diode series voltage regulator shown in the Figure. calculate V L , I Z , V R and P Z for R L = 1.2 KΩ and repeat it for R L = 3 KΩ ? Consider Zener breakdow

Magnitude comparator, circuit diagram of 2 bit magnitude comparator

circuit diagram of 2 bit magnitude comparator

Measures for improving joints and connection, Measures for Improving Joints...

Measures for Improving Joints and Connection 1. Spacing of poles: The spacing between poles (for overhead lines) is also an important requirement. Long spans will result in

Material science, advantage and disadvantage of alloying steel with silicon...

advantage and disadvantage of alloying steel with silicon

Unconditional call instruction - call instruction , Unconditional Call Inst...

Unconditional Call Instruction CALL ( Unconditional Call) Instructions :This  instruction calls the subroutine program stored at memory  location specified  in the  instruction

Digital ttl circuit, Execution of Digital Logic Circuits A safety circ...

Execution of Digital Logic Circuits A safety circuit is employed on a lathe to prevent the motor turning if it is not safe to operate. A series of 2 switches are used to check

Half-wave rectifier, Half-wave rectifier: A half-wave rectifier will j...

Half-wave rectifier: A half-wave rectifier will just only give one peak per cycle and for this reason and other reasons is only employed in extremely small power supplies. A f

Find the diameter of the antennas, Two stations, located on mountain tops 4...

Two stations, located on mountain tops 40 km apart, communicate with each other using two identical paraboloidal antennas with pencil beam- width of 1°, aperture ef?ciency of 0.8,

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd