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The Device Extraction Settings Panel
The Device Extraction Settings panel is brought up from the Settings button in the Show/Select Devices panel, which is
produced from the Device Selections button in the Edit
Menu. The panel contains controls that correspond to device-related
extraction variables. Many of these are rather obscure.
- Don't merge series devices
If checked, series-connected devices will never be merged during
extraction, overriding any Merge directive in the corresponding
device blocks of the technology file. This tracks the state of the
NoMergeSeries variable.
Similar devices may be series-merged if the common connection has no
other connection. It is occasionally useful to suppress merging to
individually measure the components of segmented devices, or in cells
where the common contact may not have a connection that is currently
in scope.
- Don't merge parallel devices
When checked, parallel-connected devices are never merged during
extraction, overriding any Merge directive in the device blocks
of the technology file. This tracks the state of the NoMergeParallel variable.
If is occasionally useful to suppress parallel merging to individually
measure segments of a multi-component device.
- Keep devices with terminals shorted
By default, if an extracted device is found to have all terminals
shorted together, it is ignored. If this check box is checked, such
devices are kept, allowing their parameters to be reported. This
tracks the state of the KeepShortedDevs variable.
- Cell flattening name keys
During extraction, there are often cells, or classes of cells, that
should not be treated as individual cells for extraction purposes,
but rather should be considered as part of their containers.
Examples are low-level cells that contain all or part of a device.
Such cells would have no counterpart in electrical mode. Generally,
physical cells with no devices and no subcells are treated this way
by default. Other cells must be specified.
The application of a Flatten property to each cell that should
be logically a part of its container with the Cell
Property Editor is an alternative to use of the facility described
here. The property application has the advantage of being persistent
when the cell is saved. Either or both methods can be used.
The entry area and enabling button allows such cells to be specified
to the extraction system. The entry area should contain a
space-separated list of words, each of which will match cell names.
The shash character ('/') is special. The matching possibilities
are:
- name[/]
This will prefix match cell names, the trailing `/' is optional. For
example if name is ``abc'', cell names abc, abc123, and abcounter would match.
- /name
This will suffix match cell names. For example, if the word is ``/bar'', cell names bar, foobar, and crossbar would
match.
- /name/
This will literally match a cell name, for example /foobar/
would match only a cell named foobar.
The list is appied only if the Use Keys button is active. This
button and entry area track the status and content of the FlattenPrefix variable. Activating the Use Keys button sets
the variable to the text, de-activating the button unsets the
variable, but retains the text in the entry area.
The remaining controls apply to the numerical solver used to extract
resistance and (microstripline) inductance.
The default mode of the solver is to divide the device body into a
grid such that the number of grid cells is fixed, independent of
device size. This gives a predictable and constant measurement time
per device, however it may provide less accuracy than other methods.
One can also choose to use a fixed grid size, in which case physically
larger devices will take longer to extract, but computed values may be
more accurate.
A third choice is to tile the structure, if possible, by using the
largest grid such that all body and contact boundaries fall on grid.
This is likely to provide the best accuracy if tiling succeeds.
- Set/use fixed grid size
If the check box is checked, the solver will use a fixed grid size as
given in the numeric entry area. When checked, other controls in this
group are grayed and their states ignored. This tracks the state and
value of the RLSolverDelta variable.
- Try to tile
When checked, the solver will try to use a grid that falls on every
edge of the contacts and device body. This tracks the state of the
RLSolverTryTile variable.
- Maximum tile count per device
When tiling is enabled, this entry area will set the maximum number of
tiles allowed in a device. This tracks the state of the RLSolverMaxPoints variable, and defaults to 50,000.
- Set fixed per-device grid cell count
This entry area supplies a number of grid cells to use per device. In
this mode, the time required for extraction is close to constant,
independent of device size. This mode is used when not tiling, and
not using a fixed grid size. This tracks the state of the RLSolverGridPoints variable, and the default value is 1000;
Next: The Edit Terminals Button:
Up: The Extract Menu: Extraction
Previous: The Device Selections Button:
Contents
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Stephen R. Whiteley
2012-04-01