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The Dump Phys Netlist Button: Dump Physical Netlist

The Dump Phys Netlist button in the Extract Menu creates a netlist file from the physical connectivity information in the current cell. Upon pressing this button, a small pop-up appears, which provides a number of format options. The options include the names from the PnetFormat blocks in the format library file, if any. The format library provides a mechanism for user-specified formatting of netlist output. The supplied xic_format_lib file contains a formatter for the Cadence DEF (Design Exchange Format) format, as well as a simple example format.

There are three built-in format choices: net, devs, and spice. Any combination of the formats can be selected, and the output will contain a block for each selected format, for each cell.

In addition, there are a number of options which modify the presentation. These include list all cells and list bottom-up, which apply to all formats, and show geometry and include wire cap. The latter options are enabled when net and spice are enabled, respectively, or when a format library choice is active.

The format options will be described in more detail below. Below the format check boxes there is a Depth choice menu which allows setting of the depth into the hierarchy to process. The user is given the option of creating the netlist to an arbitrary depth in the hierarchy. If the given depth is greater than zero, the subcells above the indicated depth will also be added to the file. If ``all'' is selected, the full hierarchy will be output.

Below the depth menu is a text entry area for the name of the file to be generated. The default name is the base name of the current cell, suffixed with ``.physnet'', to be created in the current directory. The entry area is sensitive as a receiver for drag/drop.

Any combination of the four format options may be selected. The states of the option check boxes track the status of the variables described below. The listing from the Dump Phys Netlist command will have a field of output for each selected format, from each cell. Pressing the Go button will produce the output file.

The format option check boxes are described below. The first two are options that apply to all formats.

list all cells
Subcells that are wire-only or otherwise internally flattened or ignored are normally not listed. If set, these cells are included in the listing, which may be useful for debugging.

list bottom-up
When the depth is larger than zero, this check box controls the ordering of cells in the file. When selected, the deepest cells (the ``leaf cells'') are listed ahead of their parent cells, thus the current cell will be listed last. When not selected, the listing is top-down. The current cell is listed first, followed by subcells.

The next three rows of option check boxes specify the internal formats and options for these formats.

A netlist consisting of the terminal names associated with each conductor group is generated.

show geometry
If this is selected, the net part of the output file will include a listing of the physical objects that comprise the wire net. This includes objects from the present cell, and objects that have been promoted from wire-only subcells. The objects may not exactly correspond to the physical objects, for example if the Conductor Exclude directive is given. The objects are listed in a modified CIF syntax, where units correspond to internal database units.

A list of extracted devices, with information about the device, including Measure results, is generated.

A list of the SPICE lines for extracted devices which have a Spice specification in the device block is generated.

include wire cap
When active, the SPICE listing will contain capacitors for nonzero computed wire net capacitance. These capacitors are given a special prefix ``C@NET'' which has significance to Xic, when applying LVS. The capacitors are added between the wire nets and ground. In order for wire capacitance to be computed, the Capacitance keyword must be supplied in the technology file for the routing layers.

ignore labels
From some tools, cell terminals may be indicated by the presence of a label on a Routing layer, positioned such that the label reference point touches an object on the same layer. Such labels, if found, will be used to generate a terminal list for the top-level cell in the listed hierarchy, if the existing electrical cell contains no terminals (or the electrical cell doesn't exist). If this box is checked, such labels will always be ignored.

devs verbose
This check box is active when the devs check box is checked. When checked, it enables printing of additional information in the device report in the output file. At present, it will print information about the individual components of multi-component (series or parallel merged) devices.

Additional option buttons, if any, correspond to formats specified in the format library file. If selected, a text block containing the output from the format generator will be appended to the file, for each cell. The following are available from the stock distribution format library file.

This uses a formatting script in the xic_format_lib file to generate DEF output. DEF is a common portable netlisting format. See the comments in the xic_format_lib file in the startup directory for more information.

This uses a formatting script in the xic_format_lib file to generate output in simple example format.

Each of the option buttons that correspond to an internal format or option (not the formats from the library) has a corresponding !set variable. If the variable is changed while the pop-up is visible, the pop-up will be updated. Conversely, changing the state of the option buttons will set or unset the corresponding variables. The pop-up check box will be checked if the corresponding variable is set. The names of the corresponding variables are given in the table below.

list all cells PnetListAll  
list bottom-up PnetBottomUp  
net PnetNet  
show geometry PnetShowGeometry  
devs PnetDevs  
spice PnetSpice  
include wire cap PnetIncludeWireCap  
ignore labels PnetNoLabels  
devs verbose PnetVerbose  

next up previous contents index
Next: The Dump Elec Netlist Up: The Extract Menu: Extraction Previous: The Source Physical Button:   Contents   Index
Stephen R. Whiteley 2022-05-28