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R. Timothy Edwards
d6d8620a7c
section of the tech file, which can be used to alter the layer connectivity tables from the default. This can be used, for example, to disconnect substrate and well from taps, to generate a netlist that checks for soft-connect errors.
340 lines
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340 lines
16 KiB
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<TITLE>Magic-8.3 Command Reference</TITLE>
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<BODY BACKGROUND=graphics/blpaper.gif>
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<H1> <IMG SRC=graphics/magic_title8_3.png ALT="Magic VLSI Layout Tool Version 8.3">
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<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
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<H2>ext2spice, exttospice</H2>
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<HR>
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Convert extracted file(s) to a SPICE format file.
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<HR>
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<H3>Usage:</H3>
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<BLOCKQUOTE>
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<B>ext2spice</B> [<I>option</I>] [<I>cellname</I>] <BR><BR>
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<BLOCKQUOTE>
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where <I>option</I> is one of the following:
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<DL>
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<DT> [<B>run</B>] [<I>runtime_options</I>]
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<DD> Run <B>ext2spice</B> on current cell, with command-line options
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(see Summary, below).
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<DT> <B>default</B>
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<DD> Reset to default values
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<DT> <B>format hspice</B>|<B>spice2</B>|<B>spice3</B>|<B>ngspice</B>|<B>cdl</B>
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<DD> Set output format. <B>spice3</B> is the default,
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for compatibility with <B>tclspice</B>. This is a
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change from previous versions of magic, where the
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default was <B>hspice</B>. <B>ngspice</B> is set as
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default by the <B>ext2spice lvs</B> option. <B>cdl</B>
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format incorporates some common syntax used by CDL format
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files, including placing a slash between a subcircuit's
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pins and the subcircuit name.
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<DT> <B>rthresh</B> [<I>value</I>]
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<DD> Set resistance threshold value. Lumped resistances
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below this value will not be written to the output. The
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value is in ohms, or may be the keyword <B>infinite</B>
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to prohibit writing any lumped resistances to the output.
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<DT> <B>cthresh</B> [<I>value</I>]
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<DD> Set capacitance threshold value. The value is in femtofarads,
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any parasitic capacitances to the output.
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<DT> <B>merge</B> [<I>merge_option</I>]
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<DD> Merge parallel devices/transistors. The valid merge options are:
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<BLOCKQUOTE>
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<DL>
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<DT><B>conservative</B>
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<DD> Merge transistors and capacitors having the same device
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type and node connections and having the same width and
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length. Device multipliers ("M=") are output for each
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set of merged devices.
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<DT><B>aggressive</B>
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<DD> Merge transistors having the same node
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connections and having the same length. Widths
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are summed in the final output. Merge any capacitors
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having the same device type and node connections.
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Capacitance is summed in the final output.
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<DT><B>none</B>
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<DD> Do not merge any devices.
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</DL>
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</BLOCKQUOTE>
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<DT> <B>extresist on</B>|<B>off</B>
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<DD> Incorporate output from the command <B>extresist</B> into
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the final SPICE file.
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<DT> <B>resistor tee</B> [<B>on</B>|<B>off</B>]
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<DD> Model resistor capacitance as a T-network. Each resistor
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device is split into two, with all substrate and overlap
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capacitance placed on the node between the two half-length
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devices. Without this option, resistor devices lose all
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parasitic capacitance information, and <B>ext2spice</B>
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may produce warnings about unknown nodes. However, use of
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this option may conflict with LVS (layout-vs.-schematic),
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when only one resistor is expected per drawn device.
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<DT> <B>subcircuit</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>on</B> (the default), and if the cell selected
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for SPICE output has defined ports on the top level, then
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the cell becomes a subcircuit definition in the output, and
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the output has no top-level calls to any devices. This
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format is appropriate for including in a testbench netlist,
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for example. If the top-level cell does not have defined
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ports, then there is no way for magic to determine what
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the ports might be, or what order they may be in, making
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it impossible to generate a consistent subcircuit, so in
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the absence of ports, this option has no function.
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Ports are defined by the use of the <B>port</B> method for
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labeling input and output ports. When option
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<B>subcircuit</B> is set to <B>off</B>, the top-level
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circuit will be the top level of the netlist, and it
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will have no associated subcircuit definition.
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<DT> <B>subcircuit top</B> [<B>on</B>|<B>off</B>|<B>auto</B>]
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<DD> This variant of the <B>subcircuit</B> option controls
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whether or not ext2spice generates a .subckt wrapper
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around the top-level circuit. If <B>on</B> is specified,
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a ".subckt" wrapper will always be output, regardless of
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whether or not ports are defined in the layout. If
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<B>off</B>, no ".subckt" wrapper will be output, and
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ports will be ignored (They will be regular nets in the
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output netlist). If set to <B>auto</B>, magic will
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check whether or not ports are defined in the layout,
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and generate a ".subckt" wrapper only if ports have
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been defined.
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<DT> <B>subcircuit descend</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>off</B>, the <B>subcircuit descend</B>
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option will not descend into any subcells below the
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top level, writing only the top-level circuit to the
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output. The default is <B>on</B>. This option can be
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useful for writing out digital circuits made from
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standard cells, since the digital subcircuits can usually
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be included from a vendor library.
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<DT> <B>scale</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>on</B>, the scale value is set by the
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SPICE "<B><TT>.scale</TT></B>" card, recognized by some
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SPICE parsers. All device lengths, widths, and areas
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are then given in integer units (internal database
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units). When set to <B>off</B>, all device widths,
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lengths, and areas are given in unscaled, physical
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dimensions.
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<DT> <B>short</B> [<B>voltage</B>|<B>resistor</B>|<B>none</B>]
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<DD> Determines behavior with respect to ports with different
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names connected to the same net. SPICE does not have a
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universal method for describing a net with more than one
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name. A common way of handling this is by separating
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differently-named parts of a net with a zero-ohm ideal
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resistor or a zero-volt DC source. "<B>ext2spice short</B>"
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uses one of these methods to preserve duplicate port names.
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"<B>ext2spice short resistor</B>" uses the zero-ohm resistor
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method, which "<B>ext2spice short voltage</B>" uses the
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zero-volt source method. "<B>ext2spice short none</B>"
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reverts to the default behavior, which is to remove all
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port names except for one from the netlist.
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<DT> <B>hierarchy</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>on</B>, magic will extract a hierarchical
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representation of the circuit, in which the cell hierarchy
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of the layout is represented in SPICE by
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"<B><TT>.subckt</TT></B>" macros. "ext2spice hierarchy"
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does not require that subcircuits have port labels. Each
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subcircuit will be analyzed for port connections, and port
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connections will be consistent in the SPICE output between
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the subcircuit definition (".subckt") and instantiated
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calls ("X") to that subcircuit.
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<DT> <B>blackbox</B> [<B>on</B>|<B>off</B>]
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<DD> When set to "on", views marked as abstract will be output
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as subcircuit calls ("X") but there will be no associated
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subcircuit definition output. A circuit is considered
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"abstract" if at the time of extraction it has a property
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named "LEFview". A cell will automatically be given this
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property if it is read from a LEF input file. It may also
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be given this property using the "<B>property</B>" command.
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In order for the blackbox view to be meaningful, the
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subcell must declare ports (see the "port" command).
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<DT> <B>renumber</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>on</B>, subcircuit calls (see above; only
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used for certain options such as "subcircuit", "hierarchy",
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or with extracted device types "subcircuit" or "rsubcircuit")
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are numbered sequentially "X1", "X2", etc., as encountered
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by the extractor. When set to <B>off</B>, subcircuit
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calls (when used with options "subcircuit" or "hierarchy",
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but not applying to low-level extracted subcircuit devices)
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will be rendered in the SPICE output file as "X" followed
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by the ID (name) of the cell instance.
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<DT> <B>global</B> [<B>on</B>|<B>off</B>]
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<DD> When set to <B>on</B> or default, unconnected global nets
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of the same name in subcells are merged in the output. When
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set to <B>off</B>, such nets are left unconnected.
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<DT> <I>cellname</I>
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<DD> Name of the cell to generate output for. This item is optional;
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if not specified, then ext2spice generates output for the
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current edit cell.
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<DT> <B>lvs</B>
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<DD> Apply settings appropriate for running LVS (layout vs. schematic).
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These settings are as follows:
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<UL>
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<LI> hierarchy on
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<LI> format ngspice
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<LI> cthresh infinite
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<LI> rthresh infinite
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<LI> renumber off
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<LI> scale off
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<LI> blackbox on
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<LI> subcircuit top auto
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<LI> global off
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</UL>
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This command applies the settings but does not generate output
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(<I>i.e.</I>, does not run <B>ext2spice</B>), so that settings
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can be overridden if necessary. <BR>
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(The <B>lvs</B> option was introduced in version 8.2.79).
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<DT> <B>help</B>
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<DD> Print help information.
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</DL>
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</BLOCKQUOTE>
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</BLOCKQUOTE>
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<H3>Summary:</H3>
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<BLOCKQUOTE>
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Without options, or with the option <B>run</B>,
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the <B>ext2spice</B> command converts the hierarchical extracted
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netlist information produced by the <B>extract</B> command in
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a series of <TT>.ext</TT> files into a flattened representation
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in SPICE format, used for detailed analog simulation. <P>
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<I>runtime_options</I> may be passed on the command line, and
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represent the original command-line options passed to the
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standalone version of ext2spice. A number of the original
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command-line options have been deprecated in the Tcl-based
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version, and some are duplicated by other <B>ext2spice</B> options.
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Valid <I>runtime_options</I> are:
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<BLOCKQUOTE>
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<DL>
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<DT> <B>-M</B>
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<DD> Aggressive merging of devices. If the lengths of FET
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devices connected in parallel are equal, then add their
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widths together to form a single device. Overrides any
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value specified by the "ext2spice merge" command option.
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<DT> <B>-m</B>
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<DD> Conservative merging of devices. If the lengths and
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widths of FET devices connected in parallel are equal,
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then add their widths together to form a single device.
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Overrides any value specified by the "ext2spice merge"
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command option.
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<DT> <B>-o</B> <I>filename</I>
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<DD> Save the output as file <I>filename</I> (<I>filename</I>
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must include any file extension, as there is no standard
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extension for SPICE files).
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<DT> <B>-j</B> <I>device</I><B>:</B><I>class</I>
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[<B>/</B><I>subclass</I>] <B>/</B><I>subsnode</I>
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<DD> Override values of resistance class, substrate resistance
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class, and substrate node name for device type <I>device</I>.
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Resistance classes are indexed by number and must match the
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definition in the technology file's extract section.
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<DT> <B>-f spice2</B>|<B>spice3</B>|<B>hspice</B>|<B>ngspice</B>|<B>cdl</B>
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<DD> Choose the output SPICE format for compatibility with
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different versions of SPICE.
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<DT> <B>-d</B>
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<DD> Distribute junction areas and perimeters. The Magic extractor
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computes area and perimter values per <I>node</I>, not per
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<I>device</I>. For devices that share a node, Magic cannot
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distinguish between the devices (for parasitic calculations,
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it's not necessary to distinguish between the devices).
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Normally, when generating device output, Magic writes the
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lumped area and perimeter values along with the first device
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attached to a node, and sets the area and perimeter values
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for all remaining devices on that node to zero. The <B>-d</B>
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option causes Magic to distribute the node area and perimeter
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evenly among all devices attached to that node.
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<DT> <B>-B</B>
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<DD> Don't output transistor or node attributes in the SPICE file.
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This option will also disable the output of information such
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as the area and perimeter of source and drain diffusion and
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the FET substrate.
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<DT> <B>-F</B>
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<DD> Don't output nodes that aren't connected to devices (floating
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nodes).
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<DT> <B>-t</B><I>char</I>
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<DD> Trim characters from node names when writing the output file.
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<I>char</I> should be either "<B>#</B>" or "<B>!</B>". The
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option may be used twice if both characters require trimming.
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<DT> <B>-y</B> <I>num</I>
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<DD> Select the precision for outputting capacitors. The default is
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1 which means that the capacitors will be printed to a precision
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of 0.1 fF.
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<DT> <B>-J</B> <B>hier</B>|<B>flat</B>
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<DD> Select the source/drain area and perimeter extraction algorithm.
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If <B>hier</B> is selected then the areas and perimeters are
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extracted only within each subcell. For each device in a
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subcell the area and perimeter of its source and drain within
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this subcell are output. If two or more devices share a
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source/drain node then the total area and perimeter will be
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output in only one of them and the other will have 0. If
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<B>flat</B> is selected the same rules apply, only the scope
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of search for area and perimeter is the whole netlist. In
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general, <B>flat</B> (which is the default) will give accurate
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results (it will take into account shared sources/drains).
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<DT> <B>-p</B> <I>path</I>
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<DD> Search the directory location <I>path</I> for .ext format
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files. This option is typically used with the "<B>extract
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path</B> <I>path</I>" command, because extraction and netlist
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generation are two independent steps. If this option is not
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specified, then by default the .ext file is expected to be in
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the same location as the corresponding .mag file, and failing
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that, the search path for .ext files is the same as the search
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path for .mag files.
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</DL>
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</BLOCKQUOTE>
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With options, the command sets various parameters affecting the
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output format and content. <P>
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</BLOCKQUOTE>
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<H3>Implementation Notes:</H3>
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<BLOCKQUOTE>
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<B>ext2spice</B> is implemented as a separate loadable Tcl package,
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but one which depends on the presence of the standard "tclmagic"
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package. <B>magic</B> is set up with a placeholder command for
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<B>ext2spice</B>, and will automatically load the Tcl package when
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this command is invoked. <P>
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<B>exttospice</B> is an alias for <B>ext2spice</B>, to satisfy the
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grammatically anal retentive.
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<B>ext2spice</B> is also implemented as a script to be run from
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the shell command line, where it executes magic in batch mode
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(i.e., using the <B>-dnull</B> option) and runs the ext2spice
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command automatically. With this usage, the syntax is:
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<BLOCKQUOTE>
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<B>ext2spice</B> [ <I>magic_options</I> <B>--</B> ]
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<I>ext2spice_runtime_options ext_file</I>
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</BLOCKQUOTE>
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The double-dash separates command options passed to magic on
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startup (such as "<B>-T</B> <I>technology</I>" to specify the
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technology) from those runtime options (see above) passed to
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the <B>ext2spice</B> command.
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</BLOCKQUOTE>
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<H3>See Also:</H3>
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<BLOCKQUOTE>
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<A HREF=extract.html><B>extract</B></A> <BR>
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<A HREF=ext2sim.html><B>ext2sim</B></A> <BR>
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</BLOCKQUOTE>
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<P><IMG SRC=graphics/line1.gif><P>
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<TABLE BORDER=0>
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<TR>
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<TD> <A HREF=commands.html>Return to command index</A>
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</TR>
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</TABLE>
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<P><I>Last updated:</I> September 17, 2021 at 10:12am <P>
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</BODY>
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</HTML>
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