klayout-pex-plugin-gmsh

gmsh volume meshes of KLayout-PEX PEX25D scenes, for FEM field solvers:

• the exporter gmsh
• the mesh builder that klayout-pex-plugin-elmer and klayout-pex-plugin-palace share

Usage

pip install klayout-pex-plugin-gmsh
pex25d export cell.pex25d --to gmsh --out_dir mesh

Output:

• mesh.msh: gmsh 2.2 ASCII, coordinates in µm, with physical groups
  • one volume per dielectric, the background included
  • one surface per net, floating conductor and ground plane: where it touches a dielectric
  • outer_boundary: the faces of the domain box
• mesh.json: tag, name and permittivity of every group

Conductors are not meshed, as electrostatics only needs their surfaces.

Options

Pass them with pex25d export --option NAME=VALUE (klayout-pex 0.6.3 or later) or options={...} in Python. --field_margin sets field_margin_um.

mesh.json records the sizes used.

How the default edge size does on the ihp-sg13g2 test design overlap_plates_100um_x_100um_m1_m2 (LOWER–UPPER, Elmer):

How the mesh is built

• Occupancy: the domain is sliced at every z where a solid starts or ends. Per slab, conductors and the ground plane claim their regions first, then the dielectrics by wrap depth, then the background. The resulting prisms fill the domain exactly once.
• Conformal films: grow along their WRAPS chain, as PEX25D specifies. A film wrapping a film that covers the field lies on top of it there.
• Conformal mesh: the prisms are extruded with OpenCASCADE and fragmented, so touching solids share faces.

Requirements

• klayout-pex 0.6.x (plugin API v1 is provisional)
• gmsh ≥ 4.12. IIC-OSIC-TOOLS provides 4.12.1 from APT, and PyPI has no Linux aarch64 wheel, so the code sticks to the 4.12 API.

Development

poetry install
poetry run pytest