How can I use a schematic parameter (such as R1/r = 10K) in an Explorer calculation?

Dear Bret,

Bret Howe said:

Seems like there must be a simple way to do this. I tried making R1/r a parameter in the simulation and this allowed me to sweep the parameter but I could not find a way to use this parameter in a calculation.

If I properly understand your question (apologize if I am not!), and r is your design variable, to use the value of R1/r in a Calculator expression, the syntax should be:

R1/VAR("r")

Shawn

Bret was talking (I believe) about using the parameterisation capability to set up a sweep rather than using a design or global variable, and so the VAR() approach won't work, unfortunately. 

There isn't (as far as I know) a way of retrieving the parameter values directly from ADE - there's an enhancement request, CCR 1532207, asking for this. If you've saved the instance information on the Outputs->Save All form, you can retrieve the value of an instance parameter from the simulation results using:

    pv("/Iamp/M3" "l" ?result "instance")

That isn't necessarily the same as the value you entered though, because this is after callbacks have been called - and assumes you can figure out the relationship.

The alternative is to put a variable name as the value of the parameter in the Variables and Parameters assistant, and then sweep the variable. Then you can use VAR() as Shawn suggested.

Hope that helps,

Andrew

Thanks Andrew, I will give this a try. Sounds like it will probably get me close enough for what I want to calculate. I'm surprised this functionality is not available. Seems like there would be a PAR similar to VAR that could use a parameter instead of a variable.

Bret,

The challenge is that it would need to store this data in a result database that is readily retrievable. For variables, these are in a database already for ADE because Spectre needs the variable as a parameter in the netlist; that's not quite the case with the parameterisation flow - and as I said, the parameters that are stored may not be identical to the input parameters. Yes, it would be useful, but it seems not too many people have asked for it so far.

Regards,

Andrew

Andrew Beckett said:

If you've saved the instance information on the Outputs->Save All form

I haven't found how to do this on the "Save All" form. I don't see a "Save Instance Information". Would this be added to the "save circuit information analysis" table? 

Once I have it saved, I can use pv("/I0/R0" "r" ?result "instance") in an expression?

I was able to use calcVal function to pretty much do what I needed. I use calcVal to get the resistor calculated value for nominal case and then use that value in all the other corners.

It's the element/inst row in this table - needs to be checked to be saved:

Depending on whether the resistor is directly a resistor or a subcircuit model, it may be something beneath that. The best thing to do is to look in the results browser and and find the relevant component/parameter (you should be able to look in the instance database in the results).

Andrew