[cadence newbie] plotting model parameter

[aindejeje]

Hi all,
I just want to ask, is it possible to plot a model parameter.
I want to plot vth (threshold voltage) of a transistor as i sweep input voltage.
Thanks.

 

[keith1200rs]

Vth (or more correctly vth0) does not vary when you sweep the input voltage, so it is not s logical thing to want to plot. In general model parameters are fixed, at least for each individual run of a simulation. You could make vth0 value dependant on a parameter and then plot a circuit characteristic relative to that parameter.

Maybe if you explain what you are trying to do it might help.

Keith.

 

[jimito13]

Hi aindejeje,

1.Create a file (with any text editor) with .scs extension (for example sigtype.scs) and
in this file write the following :

save * sigtype=all

2.Include the above file you just created to your model files from the ADE L environment.

3.Run the simulation with your custom swept parameter and via the menu Tools-->Results Browser of ADE L you will be able to plot any available parameter versus your swept variable.

Hope this is what you were asking for.

Regards,
Jimito13

 

[aindejeje]

Vth (or more correctly vth0) does not vary when you sweep the input voltage, so it is not s logical thing to want to plot. In general model parameters are fixed, at least for each individual run of a simulation. You could make vth0 value dependant on a parameter and then plot a circuit characteristic relative to that parameter.

Maybe if you explain what you are trying to do it might help.

Keith.

i try to plot vth as i sweep bulk voltage (vbs) of a transistor.
vth = vth0 + f(vbs)

 

[keith1200rs]

That should be easy enough provided you set up your circuit correctly. If you define vth as the gate source voltage at a (small) Idd then you create a circuit with a transistor and a fixed current source at that Idd. Then sweep the bulk voltage and plot the gate-source voltage.

Keith

 

[aindejeje]

Hi aindejeje,

1.Create a file (with any text editor) with .scs extension (for example sigtype.scs) and
in this file write the following :

save * sigtype=all

2.Include the above file you just created to your model files from the ADE L environment.

3.Run the simulation with your custom swept parameter and via the menu Tools-->Results Browser of ADE L you will be able to plot any available parameter versus your swept variable.

Hope this is what you were asking for.

Regards,
Jimito13

i got an error: "Unexpected operator "*". Expected end of file or end of line"
i included the file sigtype.scs into the Model Libraries
is it how it should be?
anyway im on spectre.

Added after 12 minutes:

That should be easy enough provided you set up your circuit correctly. If you define vth as the gate source voltage at a (small) Idd then you create a circuit with a transistor and a fixed current source at that Idd. Then sweep the bulk voltage and plot the gate-source voltage.

Keith

that is also another possible way.i will try it.
thanks Keith.

Aindejeje

 

[jimito13]

I check the file that i have as well and has the syntax i told you in my previous message...check out the characters you type,maybe you input something wrong in the file...