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Howto read port currents when having multi-terminal bus ports in VerilogA ?

Herge

Hello,

I am using multi-terminal ports in VerilogA, and would like to extract the current on one of the bus-lines using the construct I(<myport[thisline]>) where thisline is a genvar. As far as I understand the VerilogA reference manual and the Verilog-AMS specifications this should be possible, however the syntax checker (when saving the veriloga view in the library) does not allow this construct.

Am I doing something wrong ? 

**  Below the declaration of my modules and the ports :

 module qnrmesh2d(majport,minport);
   
   // Majority carriers terminals  
   inout [1:`QNRMESH2D_NPORTS] majport;
   electrical [1:`QNRMESH2D_NPORTS] majport;

   // Minority carriers terminals  
   inout [1:`QNRMESH2D_NPORTS] minport;
   electrical [1:`QNRMESH2D_NPORTS] minport;

** Example statement I would like to construct :

for (thisPort = 1; thisPort < `QNRMESH2D_NPORTS; thisPort = thisPort + 1) begin
    ...
    Enorm[thisPort] = I(<majport[thisPort]>)/(Area[thisPort]*Sigma_maj);

 ** But the syntax checker only allowed me to make the following (which I don't like because I did not want to create branches to ground) : 

for (thisPort = 1; thisPort < `QNRMESH2D_NPORTS; thisPort = thisPort + 1) begin
    ...
    Enorm[thisPort] = I(majport[thisPort])/(Area[thisPort]*Sigma_maj);
 
  • Andrew Beckett

    This would have been much easier if you'd given a complete enough example to show the problem, and also which version of the simulator you're using. I used this:

    //
    i1 (n1 n2 n3 n4) qnrmesh2d
    ahdl_include "herge.va"
    dc dc

    and

    `include "disciplines.vams"

    `define QNRMESH2D_NPORTS 2
     module qnrmesh2d(majport,minport);

       // Majority carriers terminals
       inout [1:`QNRMESH2D_NPORTS] majport;
       electrical [1:`QNRMESH2D_NPORTS] majport;

       // Minority carriers terminals
       inout [1:`QNRMESH2D_NPORTS] minport;
       electrical [1:`QNRMESH2D_NPORTS] minport;

       real Enorm[1:`QNRMESH2D_NPORTS];
       real Area[1:`QNRMESH2D_NPORTS];

       real Sigma_maj;

    genvar thisPort;

    analog begin
        @(initial_step) Sigma_maj=1.0;
        for (thisPort = 1; thisPort < `QNRMESH2D_NPORTS; thisPort = thisPort + 1) begin
            Area[thisPort]=1.0;
            Enorm[thisPort] = I(majport[thisPort])/(Area[thisPort]*Sigma_maj);
        end
    end

    endmodule

    And this works fine - if I run "spectre herge.scs". I'm using  spectre version 11.1.0.366.isr7

    Regards,

    Andrew.

  • Andrew Beckett

    This also worked in  10.1.1.392.isr22

    Andrew,

  • Herge

    Yes, Andrew, the construct I(majport[thisPort]) works fine. But this returns in fact I(majport[thisPort],0). I have multiple branches connected to node majport[thisPort], and I am afraid that I(majport[thisPort]) will not return the sum of all currents through the module port majport[thisPort] but only what flows through branch I(majport[thisPort],0).

    From my understanding of VerilogA, I was thinking I should use : I(<majport[thisPort]>)  -- which is the "(< . >)" port flow-access operator.

     Thanks. 

  • Andrew Beckett

    Herge,

    Sorry, I cleaned that up when I was messing with the code - I thought it was just you highlighting the relevant part and removed it on auto-pilot, forgetting that this means the current through the port.

    If you use the archaic syntax:

         //Enorm[thisPort] = I(<majport[thisPort]>)/(Area[thisPort]*Sigma_maj);
        Enorm[thisPort] = I(majport[thisPort],majport[thisPort])/(Area[thisPort]*Sigma_maj);

    Then it compiles (with a warning that you should use <> instead...).

    Please log this as a service request so that we can get this fixed. Hopefully you can use this as a workaround though.

    Regards,

    Andrew.

  • Andrew Beckett

    And when you log that service request, please reference this post on the forum to avoid the AE having to re-do the work... 

    Thanks,

    Andrew.

  • Herge

    Created service request no 42907084.

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