How to generate a gds with only reference cells

nolive

Hallo folks,
I hope this topic hasn't been discussed so far, I want to save a lef/Def imported database or a full gds opened file as gds file with only references and the toplevel Routing. This is what I tried so far:

A) case 1:
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1- Open a full gds file
2- select the top and save it as a new gds with the the default options except "Keep instances for dropped cells(make ghost cells)
My Remark is there are still some cells with some shapes belonging to the top-subcells(for instance ios): this not clear to me. do I missed an option in the setup?

B) case 2:
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1- I imported a def with the needed lef + technology lef (replace current layout)
2- In the option panel I had: "Via geometry 'on', Routing 'on', Net Names as properties with name 'on', Cell outline on layer with name 'on' as I want the toplevel Routing to be imported. Read all layers(additionally to the ones in the mapping table) 'on'
My remark here is after importing the design some layers are still missing! could anyone explain me what could be wrong in what I'm doing?

I'm using the klayout 0.24.6 under linux

Regards

Matthias

Hi,

There is no "write only top level cell without subcells" option currently, but you can emulate this feature.

To do so, expand the tree of your top level cell so you see the child cells. Select all child cells in the cell tree and select "Hide" from the context menu (right mouse click). On save, select "Write visible cells only". PLUS select "Keep instances for dropped cells (make ghost cells)". The latter option is a sub-feature and means that if a cell is dropped (because it's empty - see option "Write non-empty cells only" - or because it's invisible), it will still be referenced meaning there will be references without a cell (a ghost cell).

I admit that one option saying "Write top cell only" was easier to use but less flexible. The given feature you can use to selectively omit cells if you need to. But the beauty of open source is that you can add any feature you want :-)

Regarding B.) I need a testcase to tell more. LEF/DEF implementation is fairly stable but LEF/DEF undergoes frequent updates and there are some flavours around.

Matthias

nolive

Hello Mathias,

regarding the point A, I tried different possibilities to have a clean gds database with only references, The best solution I've got so far fromm Nick is just to select and delete all Layers and save this database. So thanks for the solution u provided, I'll test it and make a comment if I have some.
For the point B, as u know it's always difficult with testcase, but the question I would like to ask is if the current implementation of klayout could be lef/def version dependent? That could maybe be a hint why my the vias of nets are missing.
Regards

Olivier

nolive

Hello Mathias,
I'm still trying to understand why some vias are missing during lef/def import. the reason could be that the vias read from lef get renamed to VIA_<name in lef> and couldn't get linked during def import.
Regards.

Olivier

nolive

Hello Matthias,
sorry! your name was not correct in my previous mails
Regards

Olivier

Matthias

Hi Olivier,

LEF/DEF is undergoing some development and there are flavours out there which may behave differently. Without a testcase I can't give any advise. I am not aware of renaming vias so I cannot tell whether this is the reason.

The usual approach is to strip down a test case until it passes the security guidelines for submitting designs to public. I assume that your case can be reproduced with a very simply example.

But since the code is open source, you can basically debug the code on your site as well and submit a patch.

Regards,

Matthias