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Substrate extraction issue - gpdk090

jgmelo

 Hi all,

 I am facing a problem when trying to extract the substrate parasitics (substrate only!) with QRC from a layout, technology gpdk090. The system is a simple inverter, and I am able to do all the steps up to the av_extract sucessfully (including it - DRC, LVS, QRC extraction), except that the values of the resulting substrate resistor mesh do not make sense, i.e., my extracted inverter with substrate parasitics do not work with such values.

  At first, I thought it would be a problem about n-well/p-sub tap placing and quantity. I have tried many tapping configurations, which actually change the values of the resistances. Nevertheless, they still do not make sense.

  When I simulate my inverter with the substrate netlist generated by av_extract, I get a signal near to vdd as output, with switching characteristic, but negligible signal excursion, in the order of tens of mV (input: 1.2 V square wave). Something must be wrong with the tool usage, as the inverter layout seems correct (I checked it with more experienced colleagues). My first thought is that some file associated with extraction must be configured with voltages and signals, as QRC cannot calculate resistance values in the substrate without knowing the power and signal values that drive the circuit.

  Could someone help me on this issue? If any additional information/file/image/configuration is necessary, please ask me. I prefer not to dump lots of information in this post for the sake of simplicity for the reader. Thanks in advance!

 

 ====== Products versions ======

 virtuoso version 6.1.5
sub-version  IC6.1.5.500.11

spectre  version 11.1.0 32bit
sub-version  11.1.0.576.isr17

assura version av4.1:Production:dfII6.1.5:IC6.1.5.500.17
sub-version 4.1_USR4

-----------------------------------------------------------------
Name           : qrc - Cadence Extraction QRC - (32-bit)
Description    : Parasitic Extractor
Version        : 11.1.2-p106

===========================

Parents

  •  Hi Dominik and Queck,

      Thank you for your reply.

      I checked extview.tmp, and there were no such nets! It actually gave me a great insight, as I became even more certain that the layout was not the problem.

      So, I focused on the tool usage, and found a document suggesting to modify the "avEXT.rul" file. At first, I had something to try, but I soon found out that the

    file did not exist (the document was about Assura RF, not QRC).

      The great news is that this document showed a piece of code which had the statement "if (avSwitch = "SNA") then ...", and it rang a bell! On the LVS run form,

    there is a field labeled "Switch Names". Bingo! I clicked on it, and there were two options, one of them being SNA. I selected it, and everything ran perfectly!

      It actually strengthened my belief that most things about parasitic extraction starts at the LVS run!

      Thank you all for your help, this issue is solved!

    Best regards,

    jgmelo

Reply

  •  Hi Dominik and Queck,

      Thank you for your reply.

      I checked extview.tmp, and there were no such nets! It actually gave me a great insight, as I became even more certain that the layout was not the problem.

      So, I focused on the tool usage, and found a document suggesting to modify the "avEXT.rul" file. At first, I had something to try, but I soon found out that the

    file did not exist (the document was about Assura RF, not QRC).

      The great news is that this document showed a piece of code which had the statement "if (avSwitch = "SNA") then ...", and it rang a bell! On the LVS run form,

    there is a field labeled "Switch Names". Bingo! I clicked on it, and there were two options, one of them being SNA. I selected it, and everything ran perfectly!

      It actually strengthened my belief that most things about parasitic extraction starts at the LVS run!

      Thank you all for your help, this issue is solved!

    Best regards,

    jgmelo

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