Sweeping Vth vs L of NMOS

[arjun_rp]

Hi all,

I am Arjun, Graduate student pursuing IC Design. I am trying to sweep the Vth of transistor with respect to its length. I saved a file with .scs extension and with the content save M0:all. I selected DC analysis and in the sweep i selected component parameter and transistor M0 where i selected its length "l". I also included the .scs file into model library. But when i run the simulation i am getting a error as given below.

ERROR (SFE-430) : 'dc' : Sweeping the parameters of a subcircuit instance ('M0') is currently not supported. Please use the spectre sweep instead.

Spectre terminated prematurely due to fatal error.

What should i do to overcome this error ? Please help me

 

[Dominik Przyborowski]

You have to do parameter simulation not dc sweep.

 

[arjun_rp]

You have to do parameter simulation not dc sweep.

Can you explain with steps ?

 

[Dominik Przyborowski]

I don't know which software are You using, but in virtuoso run ADE L and choose Tools→Parametric Analysis. Of course You have to set simple DC simulation and get Vth from dc OPs.

 

[dick_freebird]

Are you trying to assert some sort of relation between L and
VT0, or are you trying to characterize (in simulation) the VT0
dependence on L (DIBL)?

The latter requires you to do nothing but step the instance
param (make it a variable) and take the data & extrapolate
the intercept, like you would at WAT probe.

The former, you'd need to make relevant compact model
params into variables or maybe table functions (like, call
L "myM0_L" and use it as the instance property -and- the
index to a VT function, maybe just a delVT(myM0_L) adder.
You ought to copy PDK model-pile to your own private model
and edit things there, hooking it up in the Setup>Libraries.