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Cadence Virtuoso layout.oa file grows in size fast and causes slow rendering

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borabut

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I'm having an issue with a design I am working on in Cadence IC 6.1.6. I have a design where I am trying to use the space based router (VSR) to route my interconnect. It works fine and I get no DRC or LVS issues but my layout.oa file size seems to nearly tripple in size. Now, the file size isn't really the problem, just something I have found to be an indicator of the problem. The problem I am having is that this layout is for a signal processing channel circuit, of which I need 16 at the next level up in the heirarchy. This is causing very slow redraw/rendering times at the higher level where all 16 channels need to be connected to the pad frame. The higher level layout will render as though it is 1980 again, taking several minutes to draw where i can see it rendering the layers in real time.

Now I know it's not my machine's hardware as an even more complex IC layout (full top level layout of a previous IC) loads up just fine with no rendering issues (and we have had no issues with the current IC design until now). I also have an older version of my signal processing channel layout where no routing has been done. If I use this layout, then there are no rendering issues at the higher levels. Additionally, with the file that trippled in size, if i delete routing it does not change the file size at all. it seems the oa database remembers information from the autorouter that is causing the slow rendering. I'm not quite sure whats going on. I'm trying to learn a bit more SKILL scripting to see if I can use that to find any more information from the database its self, but for now I am at a loss for explanation as to why this problem is occurring. If anyone has experienced something similar and knows a resolution I would be most appreciative.
 

borabut said:
I'm having an issue with a design I am working on in Cadence IC 6.1.6. I have a design where I am trying to use the space based router (VSR) to route my interconnect. It works fine and I get no DRC or LVS issues but my layout.oa file size seems to nearly tripple in size. Now, the file size isn't really the problem, just something I have found to be an indicator of the problem. The problem I am having is that this layout is for a signal processing channel circuit, of which I need 16 at the next level up in the heirarchy. This is causing very slow redraw/rendering times at the higher level where all 16 channels need to be connected to the pad frame. The higher level layout will render as though it is 1980 again, taking several minutes to draw where i can see it rendering the layers in real time.

Now I know it's not my machine's hardware as an even more complex IC layout (full top level layout of a previous IC) loads up just fine with no rendering issues (and we have had no issues with the current IC design until now). I also have an older version of my signal processing channel layout where no routing has been done. If I use this layout, then there are no rendering issues at the higher levels. Additionally, with the file that trippled in size, if i delete routing it does not change the file size at all. it seems the oa database remembers information from the autorouter that is causing the slow rendering. I'm not quite sure whats going on. I'm trying to learn a bit more SKILL scripting to see if I can use that to find any more information from the database its self, but for now I am at a loss for explanation as to why this problem is occurring. If anyone has experienced something similar and knows a resolution I would be most appreciative.
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is converting to GDS a plausible solution? it would not store any database info other than layout itself.
 

ThisIsNotSam said:
is converting to GDS a plausible solution? it would not store any database info other than layout itself.
Click to expand...

Forgive me if I am wrong but is GDS not only used as an output file to give to the foundry? Sorry, I'm merely a graduate student working in a IC lab and Im not as familiar with these tools as a professional. The design in question is still a work in progress so I need to keep it in a file format that we can easily make changes to. Is there a way to draw layouts in GDS format in Cadence IC6.1.6 or can you only draw shapes from the oa database and convert to GDS after?

If the GDS format is only an output format then I'm afraid it will not solve our issue. If I am mistaken and I can keep drawing my layout using a GDS file I would appreciate and resources that can show me how to do that.
 

I am suggesting just a workaround. Export to GDS, import back into virtuoso. It would eliminate any useless information if that really is the problem. But no, you cannot manipulate GDS files directly in virtuoso, it gets converted to its internal format no matter what.
 

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