How to find the mobility of mos in 45nm technology library

Vinod,

First of all, by asking the question to me, you're rather excluding anyone else from answering. This is not "Andrew's forum" - it's a community forum which I happen to answer a fair number of questions in my spare time.

Secondly, you provided little information about exactly what you're looking at, or which technology you're using. At a wild guess, you're looking at u0 from the models and are using gpdk045. First of all, u0 is the "low field surface mobility at tnom" - it's not the effective overall mobility. If you look in the bsim4 equations in <MMSIMinstDir>/doc/spectremod/spectremod.pdf you'll see there are several complex equations describing how effective mobility (ueff) is computed. Of course, you might not be using this model if it's a different PDK you're talking about, but there will be similar equations for other models.

It's a slight anomaly that u0 in the nch models is lower than the pch models in gpdk045 (although I suspect you made a mistake in your post because you have the NMOS higher than the PMOS, which is what you'd expect - so my guess is you got the numbers back to front if you were looking at u0). However, in my quick simulations if I look at ueff (an output operating point parameter for bsim4) it's higher for NMOS than PMOS. Since numerous parameters make up the effective mobility, it may just be that u0 is a little unusual because of the fitting of this fictional process...

All I said above may be nonsense if you're not talking about gpdk045 or had the numbers the right way around in the first place.

Regards,

Andrew.

Vinod,

First of all, by asking the question to me, you're rather excluding anyone else from answering. This is not "Andrew's forum" - it's a community forum which I happen to answer a fair number of questions in my spare time.

Secondly, you provided little information about exactly what you're looking at, or which technology you're using. At a wild guess, you're looking at u0 from the models and are using gpdk045. First of all, u0 is the "low field surface mobility at tnom" - it's not the effective overall mobility. If you look in the bsim4 equations in <MMSIMinstDir>/doc/spectremod/spectremod.pdf you'll see there are several complex equations describing how effective mobility (ueff) is computed. Of course, you might not be using this model if it's a different PDK you're talking about, but there will be similar equations for other models.

It's a slight anomaly that u0 in the nch models is lower than the pch models in gpdk045 (although I suspect you made a mistake in your post because you have the NMOS higher than the PMOS, which is what you'd expect - so my guess is you got the numbers back to front if you were looking at u0). However, in my quick simulations if I look at ueff (an output operating point parameter for bsim4) it's higher for NMOS than PMOS. Since numerous parameters make up the effective mobility, it may just be that u0 is a little unusual because of the fitting of this fictional process...

All I said above may be nonsense if you're not talking about gpdk045 or had the numbers the right way around in the first place.

Regards,

Andrew.