FLOORPLANNING

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FLOORPLANNING

• EE 449/549
• March 1, 2001
• Mangal Prasad

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What is Floorplanning?

• Floorplanning is the process in which the
  designers decide the placement of circuit blocks
  on a die in which the area required is minimized
  as well as the associated delay.

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When is Floorplanning Done?

• Floorplanning should be the first course of
  action after the transistor level design and
  verification, however, before the physical design
  itself.
• This allows the designers a way of distributing
  the spaces amongst the team.

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What Do We Need to Know?

• Total area which is available
• Area estimate for power distribution
• Area estimate for routing

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Key Decisions for Floorplanning

• How are the blocks going to be arranged on the
  chip?
• Where will the input/output pins be on the final
  package?
• How will the power be distributed, is there a
  need for more power pins?
• How is the clock going to be distributed if it is
  a time dependant circuit?

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Example Microprocessor
Here, the placement the blocks are shown where
the orange square denotes boundary of the chip.
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Connections
Here, the lines indicate the connections between
the various blocks.
The space required for routing is usually pretty
high, designers typically leave 20 of the area
for routing.
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A Word on Routing

• Routing is one of the most difficult tasks when
  putting the chip together. In order to avoid
  routing chokes, its essential that there is a
  routing channel for each block which has direct
  access to the input/output terminals of each
  block.

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Routing

• Routing takes place after the placement of the
  blocks. This is usually the last step.
• There are two levels of routing
• Local Routing
• Global Routing

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Local/Global Routing

• Local Routing
• This takes place within the block itself,
  connecting the gates, or amplifiers to make the
  complete block
• Global Routing
• This takes place between blocks. The most common
  technique used for this is channel routing.

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Example Channel Routing
The spaces between the block are routing channels
used for inter block connections.
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P A D F R A M E
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Usable Area To find the amount available,
select the area in black with the box, and at
the prompt, type box This gives you Box
height 2249, width 2249 Edit cell coordinates
ll(247, 316) ur(2496, 2565) Area
(2249)(2249) 5,000,000
T O T A L A R E A
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P O W E R D I S T R I B U T I O N
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P O W E R D I S T R I B U T I O N
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P O W E R D I S T R I B U T I O N