Using the HFSS modeler to merge arrays of vias
I do a lot of work pulling GDS files in from Virtuoso and simulating distributed elements. I generally draw two separate layouts -- one with all the via arrays conforming to the foundry design rules and another than contains large blocks of metal in place of the via arrays to speed up the HFSS solver and reduce the mesh size.
I haven't been able to really get the HFSS modeler tools (heal and simplify) to merge these via arrays satisfactorily. Ideally I could use the heal function and provide it with a length that's just longer than the via spacing that I've used in my layout and it would merge those selected objects (in this case, all the vias on a given level) within that distance.
Any one else have any experience with this? I know Momentum provides the functionality, but I really require a full 3D solver.
Regards,
J
Normally, a good, mature solver should provide functions to simplify / optimize the input structure.
When I worked on our solver, we came up with quite elaborate and refined via merging functionality.
Via merging is a standard step in parasitic extraction tools, and in some EM field solvers (like EMX).
I am surprised HFSS does not offer easy to use functionalities for that.
The most direct way to figure that out is to ask Ansys support.
But be cautious - replacing via array by a large slab of metal may incorrectly allow a lateral current flow in your simulations, you should make sure this is not happening in simulation.
Your solver needs to comprehend that, and distirnguish from a real slab of metal (some vias are made like that).
There are other operations that may be highly beneficial to simplifiy the GDS geometry, to enabel small-size mash for simulations.
One of them is polygons having too many points. For example - a circle defined by thousands fo points.
This may (depending on solver) lead to huge and unnecessary mesh size.