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CCCS unusable in graphic schematic: Spectre Netlist Does Not Include gain parameter

msharma

Hi,

 

I am using IC616, and my circuit contains a CCCS from analogLib. However, the spectre circuit netlist does not contain the gain parameter of the CCCS. Thus the output current of my CCCS always comes 0. In the siminfo, gain is mapped to fgain:  "propMappin-> nil gain fgain propbe vref" "instParameters-> gain m" "otherParameters-> fgain vref".

Also, my analogLib is called NCSUAnalogLib because we use NCSU  CDK.

 

Best Regards,

Mohit

 

  • Mohit,

    I merged your two posts together as the forum guidelines tell you not to double post.

    The propMapping looks reasonable - the parameter on the instance is called fgain, but it should end up netlisted as gain. It seems your component is a cut-down version of what is in analogLib (probably based on an old version), so you could just use our analogLib rather than the NCSU version - add:

     analogLib       $(inst_root_with:tools/dfII/bin/virtuoso)/tools/dfII/etc/cdslib/artist/analogLib

    into your cds.lib

    However, I suspect the issue might just be that you don't have $CDS_Netlisting_Mode set. In the CIW, if you type:

    cdsGetNetlistMode()

    does it return "Digital" or "Analog"? If it is "Digital", then it will not take notice of default CDF values - and so it would omit the gain parameter (if you'd left the "Current Gain" at the default value). You can solve this by doing:

      setenv CDS_Netlisting_Mode Analog   # in csh

    or:

      export CDS_Netlisting_Mode=Analog   # in ksh or bash

    before starting virtuoso. You may need to do a Simulation->Netlist->Recreate to force it to re-netlist. 

    Regards,

    Andrew.

  •  Andrew,

     

    Thanks for the suggestions. I tried both, and  cdsGetNetlistMode() returned analog. However, switching to the installation's analogLib removed this problem. So, this could be an issue of backward incompatibility.

     

    Also, regarding the double post, I had posted on 'mixed signal design' forum but had no reply for 2-3 days, and I reposted in custom ic design forum. So thanks for your reply.

     

    Best Regards,

    Mohit

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