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 Open Instance connections Assura LVS error 

Last post Mon, Oct 18 2010 8:27 AM by Ankurc. 14 replies.
Started by jdgriggs 11 Oct 2010 05:18 AM. Topic has 14 replies and 5286 views
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  • Mon, Oct 11 2010 5:18 AM

    • jdgriggs
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    Open Instance connections Assura LVS error Reply
    Simple inverter as a Ring Oscillator Design is DRC clean but the Assura LVS brings up Nets Mismatch Tool...Open Instance Connections...

    I've tried severval ways to remove error but to no avail.  Any insight will be appreciated.

    attach are the screen shot

    • Post Points: 5
  • Mon, Oct 11 2010 5:21 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply

    Here is the lvs file 

     

     

    *******************************************************************************

    ****** 5_ring_oscillator_1 schematic Ring_Oscillator_inv_sch_1 <vs> 5_ring_oscillator_1 layout Ring_Oscillator_inv_sch_1

    *******************************************************************************

     

    Pre-expand Statistics

    ====================== Original

    Cell/Device schematic layout

    (inverter schematic Ring_Oscillat...) Cell 5 5

    (buffer schematic Ring_Oscillator...) Cell 1 1

    (bufferx2 schematic Ring_Oscillat...) Cell 1 1

    (mosvar) Generic 1 1

    ------ ------

    Total 8 8

    Filter Statistics

    ================= Original Filtered

    Cell/Device schematic layout schematic layout

    (buffer) Cell 1 1 1 1

    (bufferx2) Cell 1 1 1 1

    (inverter) Cell 5 5 5 5

    (mosvar) Generic 0 0 0 0

    (mosvar_m0) Generic 1 1 1 1

    Reduce Statistics

    ================= Filtered Reduced

    Cell/Device schematic layout schematic layout

    (buffer) Cell 1 1 1 1

    (bufferx2) Cell 1 1 1 1

    (inverter) Cell 5 5 5 5

    (mosvar) Generic 0 0 0 0

    (mosvar_m0) Generic 1 1 1 1

    Match Statistics

    ================ Total Unmatched

    Cell/Device schematic layout schematic layout

    (buffer) Cell 1 1 0 0

    (bufferx2) Cell 1 1 0 0

    (inverter) Cell 5 5 0 0

    (mosvar) Generic 0 0 0 0

    (mosvar_m0) Generic 1 1 0 0

    ------ ------ ------ ------

    Total 8 8 0 0

    Match Statistics for Nets 12 12 0 0

    ==========================================================[5_ring_oscillator_1]

    ====== Open Instance Connections ==============================================

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

    Layout net: |I25/vdd should connect to:

    L |I25/avC7

    Layout net: |I23/vdd should connect to:

    L |I23/avC7

     

    ==========================================================[5_ring_oscillator_1]

    ====== Summary of Errors ======================================================

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

    Schematic Layout Error Type

    --------- ------ ----------

    - 2 Open Instance Connections

     

    • Post Points: 35
  • Mon, Oct 11 2010 5:26 AM

    • Quek
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    Re: Open Instance connections Assura LVS error Reply

    Hi jdgriggs

    I think perhaps the lvs mismatch can be resolved by joining up the vdd rails of the 2 instances. : )

    Best regards
    Quek


    • Post Points: 20
  • Mon, Oct 11 2010 5:28 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply

    Hey Quek thanks for the reply..the rails are suppose to be separated it's the buffer stage that is causing the error... as indicated in by lvs error file.

     JG

    • Post Points: 20
  • Mon, Oct 11 2010 5:32 AM

    • Quek
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    Re: Open Instance connections Assura LVS error Reply

    Hi JG

    That's right! Sorry that I had not looked at your schematic carefully. : P

    Would you please upload the following 2 ascii files and also the cls file?

    terminal>vldbToCdl design.lnn > design.lnn.ascii
    terminal>vldbToCdl design.snn > design.snn.ascii

    Please upload the files, not cut and paste.

    Thanks
    Quek

    • Post Points: 50
  • Mon, Oct 11 2010 6:01 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply

    Hi Queck

     Here are the files you requested

     

    JG

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  • Mon, Oct 11 2010 6:07 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply
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  • Mon, Oct 11 2010 6:08 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply
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  • Mon, Oct 11 2010 6:20 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply
    let's try this one more time..Quek here are the files you requested
     
    thanks
    JG
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  • Mon, Oct 11 2010 7:07 AM

    • Quek
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    Re: Open Instance connections Assura LVS error Reply

    Hi JG

    Thanks for the files. It appears that your nwells in buffer and buffer2 cells are not connected to the vdd rails. I thought that there might be something wrong with geomConnect section in extract.rul file but since the nwell of the inverters got the vdd connection, it seems to mean that Assura can see M1->cont->Nwell connectivity. This is indeed quite puzzling.

    Would you please upload a snapshot of the layout with only nwell, poly and cont layers?

    Thanks
    Quek

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  • Mon, Oct 11 2010 7:43 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply

    Hi Quek

    Here is the picture you requested also I included my LVS run files for the oscillator.  It really is a mystery for me as well bcause I have done this design 5 times already and I come to the same impass.

    Thanks for whatever insight you can provide.

    Regards

    JG

     

     

    Hi JG

    Thanks for the files. It appears that your nwells in buffer and buffer2 cells are not connected to the vdd rails. I thought that there might be something wrong with geomConnect section in extract.rul file but since the nwell of the inverters got the vdd connection, it seems to mean that Assura can see M1->cont->Nwell connectivity. This is indeed quite puzzling.

    Would you please upload a snapshot of the layout with only nwell, poly and cont layers?

    Thanks
    Quek

    • Post Points: 5
  • Mon, Oct 11 2010 7:44 AM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply
    Here's a shot with the diffusion region
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  • Mon, Oct 11 2010 4:18 PM

    • jdgriggs
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    Re: Open Instance connections Assura LVS error Reply

    Hey  Quek

    just wanted to follow-up on our conversation to see if you had any more insight

    Thanks

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  • Tue, Oct 12 2010 1:12 AM

    • Quek
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    Re: Open Instance connections Assura LVS error Reply

    Hi JG

    Thanks for the files. Unfortunately I can't find any more clues in the files too.It looks like it is better for you to file a service request to Cadence support for this issue.

    Best regards
    Quek

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  • Mon, Oct 18 2010 8:27 AM

    • Ankurc
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    Re: Open Instance connections Assura LVS error Reply
    There are some rewiring messages suggested by the assura at the end. Please try them. You can also try setting avCompareRule autoPinSwap(nil) during LVS run to disable the automatic pinswaping. Regards, Ankur
    • Post Points: 5
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Started by jdgriggs at 11 Oct 2010 05:18 AM. Topic has 14 replies.