lef generation

 Hi Suresh,

I don't usually have to create my own LEFs from GDS, but here's what I remember:

One way is to use DFII/Virtuoso to export LEF from your layout view. If you have all the pins and the boundary layer defined correctly, this should work. You may need to add blocakges, I don't recall.

Another thing you can do is use an abstract tool. I know there is one in the Cadence toolset - back when I used it, it was called Picasso. It may just be called Abstract now. It involves reading in your GDS and setting everything up for how you want pins and blockages to look, if you want antenna info, etc.

As for the tech LEF, this is usually a LEF file that just has your layer and via info, along with a few other things like manufacturing grid, etc. It does not contain any macros, but may contain SITE definitions. Sometimes a LEF that does contain the macros/std cells/rams etc. will have the tech info at the top. In that case, you would want to rip it out of each lef and just have one tech lef you read in at the beginning.

I'm thinking the tech file used for layout that you mention is the DFII tech file (usually .tf). The tech LEF is in LEF format. They contain some of the same information, but the DFII tech file will contain more detail about how the layers appear in the layout, etc.

Hope this helps - I'm a bit rusty on all of it. Most of my work happens inside Encounter these days!

 - Kari

 Hi Suresh,

I don't usually have to create my own LEFs from GDS, but here's what I remember:

One way is to use DFII/Virtuoso to export LEF from your layout view. If you have all the pins and the boundary layer defined correctly, this should work. You may need to add blocakges, I don't recall.

Another thing you can do is use an abstract tool. I know there is one in the Cadence toolset - back when I used it, it was called Picasso. It may just be called Abstract now. It involves reading in your GDS and setting everything up for how you want pins and blockages to look, if you want antenna info, etc.

As for the tech LEF, this is usually a LEF file that just has your layer and via info, along with a few other things like manufacturing grid, etc. It does not contain any macros, but may contain SITE definitions. Sometimes a LEF that does contain the macros/std cells/rams etc. will have the tech info at the top. In that case, you would want to rip it out of each lef and just have one tech lef you read in at the beginning.

I'm thinking the tech file used for layout that you mention is the DFII tech file (usually .tf). The tech LEF is in LEF format. They contain some of the same information, but the DFII tech file will contain more detail about how the layers appear in the layout, etc.

Hope this helps - I'm a bit rusty on all of it. Most of my work happens inside Encounter these days!

 - Kari