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Re: how does increase in vbs increases id in enhancement mos
anand ,
can u explain me how base wil act as another GATE......
increase in vbs wil decrease the depletion region between source & body and also bt D and Body....but channel lenght or width wil remain same???
Re: how does increase in vbs increases id in enhancement mos
if you imagine a diode between the body and the source then the more you forward bias it (upto a limit) the more the current. as it is also a cause of the change in drain current it can be thought of a second gate and thus referred to as the 'back gate'.
sohiltri said:
anand ,
can u explain me how base wil act as another GATE......
increase in vbs wil decrease the depletion region between source & body and also bt D and Body....but channel lenght or width wil remain same???
Re: how does increase in vbs increases id in enhancement mos
but body is bias to most negative potential....so even if u increase Vbs u r only decreasin reverse bias of diode u considered between source and body....u cannot say there wil be increase in current due to flow from body to source....explain me if i am wrong.....
Re: how does increase in vbs increases id in enhancement mos
No i think you don't get my point....
There can be any Id after the channel formation.....So assume there is some Id and now you apply some Vbs then Id will increase..... thats why i said...
"when vbs is incresed current flows from bulk to source which is then taken by drain........ can i say it like that can i assume it so....... "
Re: how does increase in vbs increases id in enhancement mos
Hey how does happen... an increase in Vbs can increase the current only between bulk and source... how could this be taken up by the drain... as differnt potentials are applied between source to drain and source to bulk...
Re: how does increase in vbs increases id in enhancement mos
if you analyse properly you can find that the gate voltage and the body voltage are of opposite polarity and hence the body terminal effectively aids in increase of the depth of the channel and effectively acting as another gate i.e. backgate... this leads to increase in Id...
Is this alright with u sohiltri.... i hope u get the point now...
Re: how does increase in vbs increases id in enhancement mos
Anand,
U mean to say tht consider in NMOS...gate is applied positive potential for channel formation....and thus instead of connectin body to source thus vbs=0.....we connect body to positive potential wrt source..thus increase in Vbs......now both body and gate are at same potential.....this in turn will decrease the depth of channel....
Re: how does increase in vbs increases id in enhancement mos
in case of NMOS gate is applied positive... source is applied negative and so body terminal should be applied more negative than this to backbias the body source diode.... which means that the negative potential at body terminal is gonna push more charge toward the channel further aiding the channel formation....
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