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Simulators >> Circuit Simulators >> Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
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Message started by ValarMorghulis on Apr 14^th, 2016, 10:34am

Title: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by ValarMorghulis on Apr 14^th, 2016, 10:34am

Hi,

I am using Cadence 6.1.6 and Spectre simulator.
I am trying to sweep the threshold voltage of the transistors to see the effect of variation on the output signals. Can anyone please help me how can I do that in ADE?

Thank you for your time and help.

Regards,
VM

Title: Re: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by AA on Apr 14^th, 2016, 12:08pm

I hope this tutorial helps:

http://www.engrclasses.pitt.edu/electrical/faculty-staff/levitan/1192/2008/Tutorials/Tutorial2/Tutorial_Sweep.htm

AA

Title: Re: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by ValarMorghulis on Apr 14^th, 2016, 2:03pm

Hi,

Thank you for your reply.

This tutorial tells us about how to sweep the gate voltage. I am trying to sweep the threshold voltage which is a model parameter. Do you know anything about that?

Thanks!

Title: Re: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by AA on Apr 15^th, 2016, 12:45pm

If you can change the threshold parameter manually, you can also sweep it.

Try this:

In the value field of this parameter, instead of a numeric value, enter a variable name, e.g., v_th.

In the ADE, click Variable -> Copy from Cell view

You will see your v_th variable.

Click on Tools -> Parametric analysis, and with your variable selected, enter the range.

AA

Title: Re: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by ValarMorghulis on Apr 15^th, 2016, 1:05pm

Hi,

Just to make sure, are you saying to modify the model file? In the model file Vth value of the transistor is depended on several parameters.

Or just to the define the value of applied voltage to the gate as a variable(Vgs)?

Thank you.

Title: Re: Parametric sweep of Vth and OUTPUT to see the effect of Vth variation on OUTPUT
Post by AA on Apr 18^th, 2016, 12:02pm

Sorry, my semiconductors background is rusted.

Yes, you are right, the threshold voltage is a dependent variable, therefore, you cannot sweep it. However, you can sweep the other parameters that directly influence its value iff the model exposes these process-dependent parameters to you (which I doubt).

Anyway, I found this relevant thread:

https://groups.google.com/forum/#!topic/comp.cad.cadence/jB7iz9lwiLw