The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Modeling >> Semiconductor Devices >> what is the spectre format of mos transistors ? &n
https://designers-guide.org/forum/YaBB.pl?num=1142847763

Message started by zhonghan on Mar 20^th, 2006, 1:42am

Title: what is the spectre format of mos transistors ? &n
Post by zhonghan on Mar 20^th, 2006, 1:42am

i just want to write a simplest spectre model by myself. I know the format in Hspice , like
.model mn nmos vth0=0.7 gamma=0.4 lambda=0.05. what is the coresponding format in spectre( incuding version )?
Then how to cite this model in spectre , I know " .lib 'path' corner " in HSPICE is just ok .

Title: Re: what is the spectre format of mos transistors
Post by Geoffrey_Coram on Mar 20^th, 2006, 4:15am

Spectre can parse Spice syntax, so you should be able to use the HSpice-style .model card -- particularly if you're using the .lib statement, which is also Spice.

We usually use Spectre format:

simulator lang=spectre
model mn mos1 type=n vto=0.7 gamma=0.4 lambda=0.05

What LEVEL are you using? vth0 is a BSIM3/4 parameter (level=1 uses vto), but gamma is a level=1 or level=3 parameter (bsim3v3 has gamma1, gamma2 but no gamma).

Title: Re: what is the spectre format of mos transistors
Post by zhonghan on Mar 20^th, 2006, 7:36am

Thank you , I have resolved this issue. you are right , I just copy the "vth0 " from a bsim3v3 model. By the way ,do you know the simple way to calculate the Ro of transistors with a bsim3v3 model?

Title: Re: what is the spectre format of mos transistors
Post by Geoffrey_Coram on Mar 22^nd, 2006, 9:18am

There's not an easy way directly from the parameters, but I think you get it from the slope of the Id/Vd curve (or 1/Gds for a Vd sweep).

Title: Re: what is the spectre format of mos transistors
Post by zhonghan on Mar 24^th, 2006, 11:07pm

I know the 1/ro is equal to the slope of the Id/Vd curse. But the ro is dependent on the operating point, in the other word dependent on the Vgs. So does it mean I should get different ro under different Vgs ?

Title: Re: what is the spectre format of mos transistors
Post by Geoffrey_Coram on Mar 27^th, 2006, 3:26am

Yes, you should. I suppose, if you are in saturation, then the Id/Vd curves are nearly parallel for different Vgs, so ro will not be strongly dependent on Vgs.