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why pmos threshold bigger than its nmos couterpart?

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I mean abosulute value. Why this happens? Can anyone tell me ,thank you!
 

A well-known formula for the threshold volatge:

\[V_{TH}=\Phi_{MS}+2 \Phi_{F}+ \frac{Q_{dep}}{C_{ox}}\]

Fermi potential: \[\Phi_{F} = \frac{kT}{q} \ln \frac{N_{Sub}}{n_{i}}\]


\[Q_{dep}=\sqrt{4q \eps_{Si} |\Phi_{F}| N_{Sub}}\]

It is not an accurate formula, but it pushes you to the right way.

Usually the difference between the PMOS and NMOS threshold voltages is approx. 100 mV.
I doubt it is because of the mobility.
I guess it is because of the differences in doping.
 

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    wwwww12345

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I think it depends on vth implant by the foundry.
 

PMOS have two doping i,NWELL implant and P+ implant.
 

Hi
I think the threshold voltage of NMOS and PMOS can be modified to a same level by the doping.
 

I think, too...Possible to make a techology with same threshold voltages.

But I guess it is not so important and determine a technology is a trade-off between many things.
Doping level is very important in breakdown, resistance , etc.
 

Yes, PMOS threshold for absolute value can be changed less than NMOS with threshold implant.
 

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