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 routing P/G for I/O cells 

Last post Fri, Oct 25 2013 12:20 PM by andreid. 2 replies.
Started by andreid 27 May 2013 01:43 PM. Topic has 2 replies and 3643 views
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  • Mon, May 27 2013 1:43 PM

    • andreid
    • Not Ranked
    • Joined on Fri, Jun 22 2012
    • Montreal, Quebec
    • Posts 2
    • Points 25
    routing P/G for I/O cells Reply
    Hi everybody,

    Can somebody help me, please, telling how to route P/G pins for I/O cells having a different voltage supply from the core power supply? Beside the I/O cells’ pins connected to the core and included in the verilog netlist I have few pins belonging to the I/O cell and their own power supply pins (vdde and gnde) that should be tied to a different power supply. What is the common way to do such connections?

    Thank you a lot.

     
    • Post Points: 20
  • Thu, Sep 19 2013 11:45 AM

    • Kari
    • Top 10 Contributor
    • Joined on Tue, Jul 15 2008
    • Cary, NC
    • Posts 693
    • Points 14,155
    Re: routing P/G for I/O cells Reply
    these are usually connected by abutment of the IO ring. you may need to add IO fill cells to close the gaps.
    • Post Points: 20
  • Fri, Oct 25 2013 12:20 PM

    • andreid
    • Not Ranked
    • Joined on Fri, Jun 22 2012
    • Montreal, Quebec
    • Posts 2
    • Points 25
    Re: routing P/G for I/O cells Reply
    Hi Kari,Excuse me for the delay to reply and thank you very much for your attentionI tried the abutment procedure but didn’t work from the beginning. Actually I couldn’t use the globalNetConnect to route even vdd and gnd. The tool complaints that couldn’t identify the nets and the pins. At the verification phase Encounter reported many connectivity errors. I checked, there are no gaps between IO cells zooming in, at extreme values. Additionally I must say the all the sides of the chip were carefully balanced, choosing all cells with same widths.The things started to settle the moment when I introduced in my netlist vdde, gnde (power supply for IO cells) and other rails used in the IO ring (mostly esd protection related). I don’t know how somebody else handled this stuff, but globalNetConnect couldn’t work based on LEF files. It might be because I don’t have a complete view of layers how somebody suggested. The CMOS family is very recently issued and I got the libs from the manufacturer but I cannot identify the pins vdd, vdde, gnd, gnde (& all pins related to esd protection) in Encounter. I see it in the LEF (which is text) file but I do not see in the layout. The logical pins of the IO cells are easy to identify on the screen. Is this thing normal?As I say, now I don’t have the errors reported but still a thing bothers me and if you could help me would be great. The vdd and gnd traces between the power supply cells and the ring are not equal in width and some of them go to an abutted IO cell with the power supply cell. I placed the core power cells in the middle of each side. The width of the traces is 4 um and 12um.I would like to have all of 4 um as I aked for the power ring. Also I think if I could limit their number, the connections to the abutted IO cells would disappear. The used command for srouting is:sroute -connect { blockPin padPin padRing corePin } -layerChangeRange { M1 LB } -blockPinTarget { nearestRingStripe nearestTarget } -padPinPortConnect { allPort oneGeom } -checkAlignedSecondaryPin 1 -blockPin useLef -allowJogging 1 -crossoverViaBottomLayer M1 -allowLayerChange 1 -targetViaTopLayer LB -crossoverViaTopLayer LB -targetViaBottomLayer M1 -nets { gnd vdd }                where five options are by default (M1 is bottom and LB top layer). I didn’t find in documentation what is -checkAlignedSecondaryPin 1.Can you help me please to get it right?Thank you very much.  

     

    • Post Points: 5
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Started by andreid at 27 May 2013 01:43 PM. Topic has 2 replies.