ADE explorer Ids derivative definition question

The derivative is with respect to whatever the x-axis is - ie whatever you’ve swept over, which is going to be the innermost sweep if you swept multiple variables. 

You didn’t give any information as to what you’ve swept or how to set up the sweeps or even which ADE flavour you’re using but if you plot IDC without the derivative around it you’d see what the x-axis was. If you have more than one sweep and it’s the wrong variable as the innermost the you could use the swapSweep function and then use the deriv on the result of that. 

Andrew

Hello Andrew,I am using ADE explorer,I am doing DC sweep from the calculator i have exported the expression of derivative of Ids as shown bellow.

it gives me an EVAL error as shown in the printscreen bellow.
I dont have the option to say if i want variable with resprect to Vgs or variable with respect to Vds.

Why i picked the wrong variable? it doesnt let me choose a variable.
So you straight away deriv want let me and that i should use swap sweep first?

I also tried to export a plot data to the calculator and do a derivative to it.It didnt work either.
Thanks.

First of all,, if you're doing a DC sweep, you almost certainly want to use IS not IDC. IS will give you the current versus the sweep, whereas IDC will give you the current from the operating point. Since the operating point is a single value, you can't take the derivative - but you should be able to take the derivative of the IS.

Your post is a bit confusing - you show one expression which is using IS (but has two value functions around it, so will probably destroy any sweep data and hence give you a single value at a particular corner and Vgs value, so deriv would probably fail).

I would start by building this up piecemeal if it's not working:

1. Turn off the parameter sweep in ADE
2. Make sure you can plot the current expression first by adding IS("/NM0/D") - i.e. check that the current has been saved
3. Then add deriv() around that and make sure it works (this should be with respect to Vds if that's what you're sweeping in the DC analysis)
4. Re-enable the parameter sweep - see what happens - should give you a family of derivatives wrt Vds, one for each Vgs
5. Note that if you want the swapSweep to be in the output expressions, it will have to be set up to have the "eval type" being "sweeps" or "all" (the eval type column does not appear by default). I haven't got the energy to go back and forth for the next few days explaining this (based on your previous posts) so please contact customer support if you can't work this bit out.

Andrew

First of all,, if you're doing a DC sweep, you almost certainly want to use IS not IDC. IS will give you the current versus the sweep, whereas IDC will give you the current from the operating point. Since the operating point is a single value, you can't take the derivative - but you should be able to take the derivative of the IS.

Your post is a bit confusing - you show one expression which is using IS (but has two value functions around it, so will probably destroy any sweep data and hence give you a single value at a particular corner and Vgs value, so deriv would probably fail).

I would start by building this up piecemeal if it's not working:

1. Turn off the parameter sweep in ADE
2. Make sure you can plot the current expression first by adding IS("/NM0/D") - i.e. check that the current has been saved
3. Then add deriv() around that and make sure it works (this should be with respect to Vds if that's what you're sweeping in the DC analysis)
4. Re-enable the parameter sweep - see what happens - should give you a family of derivatives wrt Vds, one for each Vgs
5. Note that if you want the swapSweep to be in the output expressions, it will have to be set up to have the "eval type" being "sweeps" or "all" (the eval type column does not appear by default). I haven't got the energy to go back and forth for the next few days explaining this (based on your previous posts) so please contact customer support if you can't work this bit out.

Andrew