changing parameters in virtuoso

[praveen450]

Hi,
I'm designing a circuit in cadence virtuoso.I want to change the parameter values in the circuit.

For example,I want to change the threshold voltage of a nfet transistor.While running the simulations I changed the threshold value in ADE environment by changing Vth in nfet.scs file.I'm not seeing any change after doing this.Still nfet transistor has previous Vth.

The question is am I changing the threshold value in the correct file?.

Can anyone help me in this regard

Thanks in advance,
Praveen

 

[dick_freebird]

You should be able to inspect the netlist and see what
model is called out, and inspect the setup model libraries
to see where the models are pulled from.

If you change the bottom-level file and don't do anything
to make the ADE think there's a reason to netlist, you
may just keep running the old netlist and not repeat the
model readin / evaluation. Try a "recreate netlist" and
see if that does anything.

You can change the VT value in the model file to a
variable (e.g. VTnfet) and then the simulation should
fail and demand that you set the variable to something.
You can then use that variable in Parametric Analysis
or whatever.

 

[praveen450]

I also changed the path of model library files and when I created the netlist it is giving the modified path but still showing the old Vth.