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Displaying current through a pin

mhkvy4

I was trying to figure out how to display current flowing into a pin in Cadence. I need to calculate the total power dissipated by the circuit. 

I clicked on Outputs>To be saved and then clicked on the pins I was interested in. Where are the current values saved? And is there a way to display them for different schematic pins like for DC node voltages. 

I am also getting the following warning. 

WARNING (ADE-3022): Schematics of the following net names could not be mapped to
simulators. Ensure that the specified schematic names are valid.
/I7/vdd! /I12/vss!

  • My guess is that you have clicked on the pin of a vdd or vss tap symbol (maybe from the basic or analogLib libraries) - these are not pins, but are just a way of naming a net to be a global net. Because they're not pins, there are no currents flowing through them.

    If you save the currents going through a instance's pin, the results will be generated in the psf results and you should be able to annotate them (assuming its a DC operating point simulation).

    Regards,

    Andrew.

  • Hello Andrew,

    Thanks for the clarification about the Vss and Vdd tap symbols
    could you explain what you mean by psf results? once I do a dc operating point simulation and save the op. point, how do I see the currents I selected on the schematic ( flowing through the pins of the instances) if I have saved the outputs ?

  • psf is the directory where the results are saved - it contains a set of databases for each analysis. You asked where it was saved, so I said where it was saved.

    I don't know which version you're using, but one issue may be that your symbols may have been created with the wrong template. If they were not created with the "artist" or "analog" template, they may not have the cdsTerm() labels on the symbol which is used as the placeholder for where the currents (or voltages) are displayed.

    How to enable display of currents is somewhat version dependent. In IC616 and later, you can display the currents using an info balloon - when you hover over the instances, but I won't go through the explanation of how to do that unless I know which version you're using (use Help->About in any of the windows - please give the full version number). That's why we suggest providing that information in the forum guidelines (the pinned post at the top of each forum).

    Regards,

    Andrew

  • Thanks for telling me what psf is. Sorry about not providing the version number. It is 6.1.6. how do you enable instance currents in this version ( the info balloon you spoke of)? 

  • OK, the first thing to check is to open the symbol for the block in question, and see if it has labels of the form cdsTerm("pinA") cdsTerm("pinB") etc on the pins. If it has, then all you need to do is ensure you've saved the terminal currents on that instance (outputs->to be saved->select on schematic, and either click on the pins, or click on the instance to select all pins for that instance), and then after simulation do (in the schematic) View->Annotations->DC Currents.

    If you don't have the cdsTerm() labels, you can either add them (using the create label command in the symbol editor), or having done the steps above, do View->Info Balloons (to turn on info balloons) and then hover over the instance to show the terminal currents in a table over the instance.

    Regards,

    Andrew.

  • Thanks Andrew. That helped a lot.

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