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How do we size NMOS and PMOS to increase the threshold voltage??

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mujju433

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How do we size NMOS and PMOS to increase the threshold voltage??

NMOS AND PMOS

I remember that shrink L will downgrade Vt, shrink W will increase Vt.

Re: NMOS AND PMOS

Dear friend.

To increase Vt,

1) Either increase Width
2) increase oxide thickness
3) Increase oxide capaitance
4) increase mobility (applicable for short channel)

Hope helps u

Phutane

mujju433

Points: 2
NMOS AND PMOS

hmm
right

But if u increase the width then the area will be more right??
and If u increase oxide capacitance then the delay will be more so wt shd we do at that time?

Re: NMOS AND PMOS

Dear mujju,

Of course there will be increase in area, but to acheive something

we need to sacrifice some thing right.

also we dont try to increase capacitance , also it si not in our hands.

Nice

phutane

mujju433

Points: 2
NMOS AND PMOS

the threshold voltage is only a function of the manufacturing technology
and the applied body bias VSB. The threshold can therefore be considered as a constant
over all NMOS (PMOS) transistors in a design.

mujju433

Points: 2
NMOS AND PMOS

I am getting confused bestwonbin bcoz phutane is saying something and ur saying something

Is this purely related to body effect or ? other than this as it is said by phutane??
wt do u say?

Re: NMOS AND PMOS

In ans provided by bestwobin, the equation of Vt is derived for two dimentional mos view. If Vt equation is found by considering all effects, it will contain the terms W & L. For this check out BSIM3 parameters equations.
Well Vt is directly proportional to L and inversly proportional to W.

NMOS AND PMOS

phutane said is more emphasize the manufacturing process,and i consider little about that.

In the formula,VT0 is an empirical parameter,which is the threshold voltage for VSB = 0, and is mostly a function of the manufacturing process.there is more details in <Digital Integrated Circuits>,Jan M. Rabaey.

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