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Short Violations in Encounter

iopad

After doing placement and trial route in Encounter, I get over 1000 "short violations". The violations are all concentrated within the small left corner of my design. The violations are between wire/wire, via/wire, via/blockage etc. Strangely I don't get congestion markers in the left corner. The shorts are all on metal layers M1 and M2. What should be the starting point in resolving this problem?

SHORT: Regular Via of Net DP_OP_8555J1_629_6502_n22 & Pin of Cell DP_OP_8555J1_629_6502_U39  ( M1 )
Bounds : ( 53.930, 72.240 ) ( 54.040, 72.265 )

  • If your violations are localized to a region then your first approach should be to spread out the cells (that is if the tool isn't doing that already).
    - Add partial placement blockage and restrict placement to about 10%-20% less than average row utilization of the design.
    - Alternatively, if the congestion is restricted to a module try adding module padding

    Since the violations are mainly on M1 and M2 that suggests the std. cell pin density is very high in this region. If this doesn't improve routing, you may want to check the type of check the type of cells in this region, are they regular 2/3 pin cells (like nand, buff etc) or more complex (like mux or aoi).

  • Thanks for the reply. I have tried partial placement blockage and using "congOpt" post-placement but still get short violations after trial route. See the attached image for the placement of the cells where the violations occur. What command does the module padding?

  • trialRoute is not intended to be a DRC-clean route. There may be shorts, etc. See what violations you have after nanoRoute.

  • Nanoroute wasn't able to complete due to "too many violations". I have some 1000 short violations during nanoroute. So presently I'm using trial route to verify floor plan and placement before moving to nanoroute.

  • I think you should find out why nanoRoute is having so much trouble. Sounds like it could be a floorplan issue, but it's possible that if nanoroute is allowed to continue, it will clean things up eventually. In any case, you should run nanoroute with setNanoRouteMode -drouteAutoStop false, so that it will keep going and then you'll have a route (with violations) to look at and diagnose the problem.

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