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Abstract Generator: Terminals not accessible, off-grid pins

marten

Hi there,


abstract generation for a simple inverter layout prompts some warnings about terminal inaccessability and off-grid pins:

...
INFO (ABS-19026): Generating detailed blockages for layer VV
INFO (ABS-19026): Generating detailed blockages for layer LB
*WARNING* (ABS-15061): Cell INV_X1: The Terminal gnds pin has no accessible pins on the Metal1-Metal2 Routing grid.
*WARNING* (ABS-15061): Cell INV_X1: The Terminal gnd pin has no accessible pins on the Metal1-Metal2 Routing grid.
*WARNING* (ABS-15061): Cell INV_X1: The Terminal A pin has no accessible pins on the Metal1-Metal2 Routing grid.
*WARNING* (ABS-15063): Cell INV_X1: The y prBoundary's 1.880000 dimension is not a multiple of Metal2 pitch 0.100000
*WARNING* (ABS-11026): Unable to get the logical view of Cell INV_X1, Bus Annotation of Abstract can not be done
INFO (ABS-11901): Cell INV_X1: Step Abstract finished
INFO (ABS-15058): Metal1 pitch = 0.136 microns, Metal1 offset = 0.068 microns
INFO (ABS-15058): Metal2 pitch = 0.1 microns, Metal2 offset = 0 microns
INFO (ABS-15058): Metal1 pitch is 0.019 microns  greater than line to via spacing
INFO (ABS-15058): Metal2 pitch is 0 microns  greater than line to via spacing
*WARNING* (ABS-15059): Diagonal vias are NOT legal with this metal1 and metal2 pitch
INFO (ABS-15058): Number of cells checked = 1
INFO (ABS-15058): Number of cells whose pr boundary is not multiple of x pitch = 0
INFO (ABS-15058): Number of cells whose pr boundary is not multiple of y pitch = 1
INFO (ABS-15058): Number of cells with off grid terminals or blockages = 0
INFO (ABS-15058): Number of cells with off grid terminals = 0
INFO (ABS-15058): Number of cells with off grid pins = 1
INFO (ABS-15058): Number of cells with inaccessible terminals = 1
INFO (ABS-15058): Number of terminals checked = 6
INFO (ABS-15058): Number of terminals off grid = 0
INFO (ABS-15058): Number of terminals inaccessible = 3
INFO (ABS-15058): Number of pins checked = 15
INFO (ABS-15058): Number of pins off grid = 4
INFO (ABS-15058): Number of pins off grid in x = 4
INFO (ABS-15058): Number of pins off grid in y = 0
INFO (ABS-15058): Number of blockages checked = 0
INFO (ABS-15058): Number of blockages off grid = 0
INFO (ABS-15058): Number of blockages off grid in x = 0
INFO (ABS-15058): Number of blockages off grid in y = 0
INFO (ABS-14028): Cell INV_X1: predefined site CoreSite will be used

...

The Layout contains pin shapes for  input / output pins, vdd/gnd, vdds/gnds (well-taps), and they all were inserted to be on grid, centered at: (x-Offset M1 +  x-Pitch M1, y-Offset M1 + y-Pitch M1).
So my Questions are:

  1. What is causing the pins to be off grid and why are not all off grid?
  2. What is the difference between pin and terminal?
  3. How can I determine which pins are reported as off-grid ?
  4. Why are those 3 Terminals inaccessible, how can this be resolved?
  5. Signal Pins are on metal 1, while power-rails are on metal 2. Should I introduce M2 for in/out-pins aswell?

  • marten

    Playing around with the abstract options, I am now able to ask some of the questions by myself:

    marten said:

    1. What is causing the pins to be off grid and why are not all off grid?

    These Warnings occure when fracturing pins is enabled: (absSetBinOption( "Core" "AbstractPinFracture"        "true"))
    Pins get fractured into rectangular shapes and some of those shapes are of grid.

    marten said:

    2. What is the difference between pin and terminal?

    Terminals represent the logical connections of the cell / block, pins are the physical representation of a terminal.

    marten said:

    Why are those 3 terminals inaccessible, how can this be resolved?

    I guess this is because of blockages. Whenn disabling fracturing of pins, A and gnds get accessible but gnd still remains inaccessible.
    This is weird because all other power rails can beaccessed propperly.

    So the remaining question is. how can I fix this issue:

    *WARNING* (ABS-15061): Cell INV_X1: The Terminal gnd pin has no accessible pins on the Metal1-Metal2 Routing grid. ?


    Cheers,

    Marten

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