Folks, where is the best place to find info about ...
# caravelt
Tobias Strauch
10/05/2022, 10:05 AMFolks, where is the best place to find info about Caravel's power routing concept ? Thanks.
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Mitch Bailey
10/05/2022, 10:13 AMCaravel’s power routing or openroad’s power routing? Caravel is the fixed framework. openroad does the power routing inside the synthesized place and route region.
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Tobias Strauch
10/05/2022, 10:21 AMI have 27 macros on Caravel's wrapper level, and I want to optimize the power routing.
For that I need to understand the concept and I was wondering where I can find the latest and greates documentation about it.
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Harald Pretl
10/05/2022, 10:50 AM@Tobias Strauch Not sure what you mean by concept. All supplies are routed in a grid across the user area (met5 horizontal, met4 vertical), and the macros contact the grid. met5 is not to be used by the macros internally, and met4 is cut where a macro sits. How the supply grid is constructed is defined by the OpenLane PDN settings.
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Tobias Strauch
10/05/2022, 11:26 AM@Harald Pretl Before I bother others with my questions, I simply wanted to check if my understanding is right and if there is a documentation. I know these things since I did my first chip 25 years ago as a student, but I was searching for Caravel specific documentation. Simple as that.
The met4 power routing simply doesn’t look right, despite LVS pass. This is done without PDN optimizations.
But the question remains, is there a documentation about the power rounting ?
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Matt Venn
10/05/2022, 3:36 PMIt looks 'normal' to me
Matt Venn
10/05/2022, 3:38 PMt
Tobias Strauch
10/05/2022, 4:00 PM@Matt Venn Thanks for the link.
Regarding the screenshot. Some of the 12 squared minimacros are not met4 connected, aren't they. The top 4 ones have one met4 strap to top, the other ones are floating. LVS passes.
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Matt Venn
10/05/2022, 4:02 PMaren't they connected via met 5 horizontal straps?
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Tobias Strauch
10/05/2022, 4:25 PMThanks you for looking at it and for your feedback.
So you say that my met4 paranoia is a little bit over the top. Since the met4 routing is not regular in structure, I was a little bit wondering.
I will try to improve the powr routing within the minimacros, but any hint how to improve the met4 routing on top level ?
Cheers, Tobias
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Matt Venn
10/05/2022, 4:33 PMmet5 should be uninterrupted. Also, I've seen on several occasions that if the pdn really is broken, the the LVS will fail
Matt Venn
10/05/2022, 4:34 PMit basically looks ok to me
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Tobias Strauch
10/05/2022, 4:38 PMThat's good to know, thanks a lot again!
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