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Abstract Generator + Encounter and DRC Errors

nevsan
nevsan over 11 years ago

I'm using Abstract Generator to generate abstract information for custom cells that I pull into encounter for place and route along side a standard cell library.

I've gotten the flow working and but have some small issues I'd like help on.

'Abstract' View 

If I use abstract generator to make an 'abstract' view for my cell from the layout view, then Encounter will place and route it just fine, but will complain about many 'shorts' when checking geometry (and it slows down detail route since it's trying to fix those shorts). The thing is, my cell contains nets on METAL2 and METAL3 that connect to pins that are defined on METAL1. Encounter is connecting to these pins via planar connections to these METAL2 and METAL3 nets. This is fine, and I would even prefer that Encounter do that rather than going out of its way to make a via.

The resulting layout is perfect (DRC and LVS clean when written to OA and checked with PVS). However, it does leave unsightly flashing white boxes in the OA layout (how do I get rid of these?), and detail route takes a long time because it's trying to fix DRC violations that shouldn't have been flagged as errors in the first place.

Layout-Abstract Dual View

I then tried using the Layout Dual view approach, by deleting the abstract views, setting

  1. absSetOption(“AnnotateLayoutDualView” “true”) 

and letting abstract generator put the required annotations in the layout view. If I add 'layout' to the abstract views used by Encounter, it is able to place and route the cells as before, but this time Encounter doesn't complain about shorts (even though it is connecting to the nets on METAL2 and METAL3 as it was before) and detail route finishes MUCH more quickly.

It seemed like the problem was solved until I pulled the design into OA and checked it with PVS. It almost seems like Encounter had no idea about my cell's internal metal routes when routing the design, because it was full of DRC errors caused by things like badly placed vias.

 

I like the idea of layout-abstract dual views and would prefer to make that option work, but right now the only way I can get a proper layout is by generating the 'abstract' view and dealing with the flashing boxes and long route times.

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