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# Using ADE calculator on x-axis with DC sims

Last post Sun, Feb 22 2009 7:11 PM by sporre. 2 replies.
 Started by sporre 08 Feb 2009 07:56 AM. Topic has 2 replies and 2765 views
• #### Sun, Feb 8 2009 7:56 AM

• sporre
• Joined on Sun, Feb 8 2009
• Posts 5
• Points 70
Using ADE calculator on x-axis with DC sims
 When I run a DC sim with a swept DC voltage, such as a gate voltage, and then I plot a current, the plot puts the current on the y-axis and the swept DC voltage on the x-axis.  Is there any way to apply calculations to the x-axis (swept DC parameter) the way that you can with the y-axis data?  For example, when I sweep the gate voltage on a PMOS device, I would rather plot Ids versus Vg-VDD instead of Vg with respect to ground.   Does anyone know if this is possible?
• Post Points: 20
• #### Fri, Feb 20 2009 10:20 AM

• Jim McMahon
• Joined on Fri, Feb 20 2009
• San Jose, CT
• Posts 21
• Points 355
Re: Using ADE calculator on x-axis with DC sims
 Yes.After the simulation completes and the DC results are plotted, do the following:1. Open the Calculator and create an expression for the x-axis quantity. E.g. VS("/gate") - VS("/vdd"). 2. Make sure the plot mode is set to "append" and plot the expression. The expression should now visible in the graph window.3. Double-click on the x-axis to access the axis attributes. Change the "Plot vs." field to above expression and "OK" the form. Jim
• Post Points: 20
• #### Sun, Feb 22 2009 7:11 PM

• sporre
• Joined on Sun, Feb 8 2009
• Posts 5
• Points 70
Re: Using ADE calculator on x-axis with DC sims
 Jim, thanks for replying.  I tried it and it worked.  The timing of your answer was perfect, because I had another school assignment tonight that I needed this answer for.  Tonight I actually needed to do the same thing for a transient simulation, and that worked also.  For example, I needed to plot Vout vs. Vin for a digital gate using a transient sim.  The same method works.
• Post Points: 5