The Inductance/Resistance Extraction Interface

The interface uses an external program to extract inductance and resistance values along conducting features in the layout. The interface currently supports the original FastHenry program from MIT, and (presumably) all input format compatible successor and derivative programs that can be run from a command line.

• FastHenry-WR from Whiteley Research. The program is available available in the free software archive on the Whiteley Research web site. This package has been updated to build easily with newer compilers. It has been extended to support superconductors, and incorporates features to accelerate computation.

• FastHenry from MIT. This is the original FastHenry three-dimensional inductance extraction program.

This is the second generation interface to FastHenry. The original extraction interface, found in releases 4.0.8 and earlier, was quite a bit more complicated. The present interface affords at least the following simplifications:

• The interface presently takes material from the current cell as input, there is no need to select and save things into the interface.

• There is no ``dataset name'', the file names use the current cell name as a base name.

• There is no longer a graphical ``partition editor''. This was too cumbersome. Instead, a simple automatic refinement provision is included. It is hoped that one day auto-refinement will be built into a FastHenry successor program, as was done in the FasterCap program from fastfieldsolvers.com.

• There is no longer a graphical terminal definition editor. Instead, a special layer is used to define terminal areas.

The new interface, however, is much more flexible and powerful than the original interface.

• There is no longer a fixed assumption that layers are planar, or that layer ordering must begin with a conductor and alternate with insulators. Layers can appear in any order, and any layer can be planarizing, or not. If a layer is planarizing, it will have variable thickness such that the top surface is in one plane.

• There is a new layer-sequencing engine (see 12.8) that is also used by the Cross Section display command (in the View Menu), as well as for capacitance extraction. Thus, the cross section display will always faithfully represent the assumptions used in the interface. Layer ordering is basically that shown in the layer table, though Via layers are allowed to be out of sequence (likely for drawing visibility reasons). The ``real'' position of a Via layer can be obtained from the layers it references.

• Geometry is taken from the current cell, to all levels of the hierarchy. There is provision for use of a special masking layer. If this layer is found in the layout, geometry will be clipped to the patterning on this layer.