Wednesday, 17 July 2013

Floorplan Control Parameters

The following are the Control Parameters during Floorplan

1. Aspect Ratio:

  • Core Utilization
  • Aspect ratio (H/W)
  • Row/Core ratio

2.Width and Height:

  • Width
  • Height
  • Row/Core ratio

1. Aspect Ratio (Ar):
 Aspect ratio is the ratio between vertical routing resources to horizontal routing resources. If you specify a ratio of 1.00, the height and width are the same and therefore the core is a square. If you specify a ratio of 3.00, the height is three times the width.

                             Aspect Ratio(Ar) = Horizontal routing resource (H)/Vertical routing resource (V)

  • Core Utilization (Cu): It indicates the amount of core area used for cell placement. The number is calculated as a ratio of the total cell area (for hard macros and standard cells or soft macro cells) to the core area. A core utilization of 0.8, for example, means that 80% of the core area is used for cell placement and 20 percent is available for routing.
            Core Utilization(Cu) = Standard Cell area/(Row area + Channel area)

  • Row to Core Ratio (Rcr): It indicates the amount of channel space to provide for routing between the cell rows. The smaller the number, the more space is left for routing. A value of 1.0 leaves no routing channel space.
          Rcr = Row area / Core area (H x V)

  • Total utilization T(F) of floorplan F is derived using the following equation: 
                                T(F) = (A(m) + A(p) + A(s) ) / A
                                     where A(m) = Area occupied by macros
                                                A(p) = Area occupied by Pads/ Pad fillers
                                                A(s) = Area occupied by Standard Cells
  • Cell row utilization C(F) of floorplan F is approximated using the following equation:
                          C(F) = A(s) / A(R –union(B, E, m, p))
                               Where R= All cell rows
                                           B= All placement blockages
                                           E= Exclusive Regions


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