Stats

  • Locked Locked
  • Replies 8
  • Subscribers 126
  • Views 19312
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

How to probe in av_extracted view?

starsky

 Hello All,

I am using the cadence spectre IC5141. I am trying to simulate LC-VCO through assura layout.

I have cleared all DRC, LVC and have an av_extracted view. But when I simulate the layout / av_extracted view of this LC-VCO from config it doesnt work /oscillate. 

I want to probe on various points say vdd, gnd etc in the extracted view itself and see if all the voltages sources etc are connected properly. 

How to do that?

Thanks in advance.

  • Hi starsky

    What you are looking for is "out of context" probing. This means to simulate using av_extracted view and to do subsequent probing using the schematic view. In short, to backannotate the results from the extracted view to the schematic for easier viewing and analysis.

    After doing the simulation, simply descend back into the schematic view from the top level config view. You will see "out of context" in the title bar of the window. You can now proceed as per usual when analysing schematic simulation results.

    For more details, you can refer to the parasitic simulation user guide located at $CDSHOME/doc/parasim/parasim.pdf. It contains a tutorial which shows the parasitic simulation flow. The tutorial database is located at $CDSHOME/tools/dfII/samples/tutorials/msps.

    Best regards
    Quek

  • You can probe the av_extracted view directly after simulation. Simply descend edit the symbol in your testbench and choose the av_extracted view, then use the Direct Plot form in ADE to choose which net (or segment of a net) you want to plot. You should be able to get currents as well with the correct save statements.

  •  Thank you guys,

    I have 1 more question...when I simulate the av_extracted view it is giving me error  saying:

    Only one connection to the following 4 nodes :

    I0.avc9, I0.avc6, I0.avc8, I0.avc7

    No DC path from node  I0.avc9 to ground, Gmin installed to provide path.

    No DC path from node  I0.avc6 to ground, Gmin installed to provide path.

    No DC path from node  I0.avc8 to ground, Gmin installed to provide path.

    No DC path from node  I0.avc7 to ground, Gmin installed to provide path.

    My question is how do I fine out where these nodes are in extracted view?

     Thanks.

     

  • One thing worth pointing out too is that you need to ensure the layers used in the av_extracted view are valid and selectable in the LSW/layer palette. Often Assura rules create the interconnect layers on the "net" purpose, and not everyone has these purposes (for the metal layers, for example) valid and selectable (so you may need to make them valid).

    I've seen this happening before when people have difficulty probing nets to plot from extracted views.

    Best Regards,

    Andrew

  • Thanks Andrew,

    Can you please tell me where to go and  make these nets valid?

     

    Thanks and regards,

    starsky


  • Hi starsky

    Andrew meant making the layers as valid, not the nets. You can go to "LSW:Edit->Set valid layers" to do this.

    Best regards
    Quek

  •  Hi Quek,

     That works :)

     Thanks a lot.

     

  • You asked earlier about locating the nets such as avc6. You should be able to open the extracted view, and then under the Assura menu probe the net (you can type in the net name). I forget the details of what the menu is called, and can't test it right now.

    Most likely it's due to some floating pieces of metal, from which there is only capacitative coupling. That probably wouldn't cause any trouble though.

    Regards,

    Andrew.

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.