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cherin
Joined: 18 May 2008
Posts: 8
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 05 Nov 2009 18:57 Floorplan aspect ratio |
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I am trying to compare the area of two circuit designs in Magma. So, I thought i would specify the same aspect ratio for both the circuits and compare the final chip area. But for one particular design. [ I had specified an aspect ratio of 0.56 and a utilization factor of 0.4 ]
It so turned out that Magma could manage only a 27% utilization for one of the circuits [Circuit A], whereas for the other one [Circuit B], it could achieve 41%.
But for circuit A, on specifying an aspect ratio of .25 and utilization of 0.4, Magma could come up with a chip of utilization of 40%.
(Q no.1) But wouldn't it be practically difficult to fabricate a chip with an aspect ratio as low as .25? Is there any generally accepted guidelines-- ie, a range of aspect ratios that are considered okay?
(Q no.2) Is there any similar guidelines for an 'acceptable utilization factor'? Is 40% too low?
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cherin
Joined: 18 May 2008
Posts: 8
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06 Nov 2009 4:39 Re: Floorplan aspect ratio |
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Well, I messed up the question with a lot of unnecessary details! Let me put it in a simple way
1) I am sure that an aspect ratio of 0.1 is too low! but i guess 0.5 is alright. So is there any lower limit for the aspect ratio which is acceptable?
2) A utilization of 100% is ideal. But there is no space for routing the wires. But if i select 40% , would it be too low?
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arjun1110
Joined: 03 Jul 2008
Posts: 76
Helped: 2
Location: Bangalore,India
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06 Nov 2009 6:33 Re: Floorplan aspect ratio |
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Hi Cherin,
2) A utilization of 100% is ideal. But there is no space for routing the wires. But if i select 40% , would it be too low?
If it is 40% at floorplan stage then it is very less.
Start floorplan with utilization of 65% to 70 % by the time you complete routing utilization might have gone upto 90%.
Regards
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