SIM(5)								File Formats Manual							    SIM(5)

NAME

       sim - format of .sim files read by esim, crystal, etc.

DESCRIPTION

       The  simulation	tools crystal(1) and esim(1) accept a circuit description in .sim format.  There is a single .sim file for the entire cir-
       cuit, unlike Magic's ext(5) format in which there is a .ext file for every cell in a hierarchical design.

       A .sim file consists of a series of lines, each of which begins with a key letter.  The key letter beginning  a	line  determines  how  the
       remainder of the line is interpreted.  The following are the list of key letters understood.

       | units: s  tech: tech format: MIT|LBL|SU
	      If  present,  this  must be the first line in the .sim file.  It identifies the technology of this circuit as tech and gives a scale
	      factor for units of linear dimension as s.  All linear dimensions appearing in the .sim file are multiplied by s	to  give  centimi-
	      crons.  The format field signifies the sim variant. MIT and SU are compatible and understood by all tools. LBL is understood only by
	      gemini(1).

       type  g	s  d  l  w  x  y  g=gattrs  s=sattrs  d=dattrs
	      Defines a transistor of type type.  Currently, type may be e or d for NMOS, or p or n for CMOS.  The name of the node to	which  the
	      gate, source, and drain of the transistor are connected are given by g, s, and d respectively.  The length and width of the transis-
	      tor are l and w.	The next two tokens, x and y, are optional.  If present, they give the location of a point inside the gate  region
	      of  the transistor.  The last three tokens are the attribute lists for the transistor gate, source, and drain.  If no attributes are
	      present for a particular terminal, the corresponding attribute list may be absent (i.e, there may be  no	g=  field  at  all).   The
	      attribute  lists	gattrs,  etc.  are  comma-separated lists of labels.  The label names should not include any spaces, although some
	      tools can accept label names with spaces if they are enclosed in double quotes.  In version 6.4.5 and later the default format  pro-
	      duced  by  ext2sim is SU. In this format the attribute of the gate starting with S_ is the substrate node of the fet. The attributes
	      of the gate, and source and substrate starting with A_, P_ are the area and perimeter (summed for that node only once) of the source
	      and drain respectively.  This addition to the format is backwards compatible.

       C n1 n2 cap
	      Defines  a  capacitor between nodes n1 and n2.  The value of the capacitor is cap femtofarads.  NOTE: since many analysis tools com-
	      pute transistor gate capacitance themselves from the transistor's area and perimeter, the capacitance between a node  and  substrate
	      (GND!)  normally	does  not  include the capacitance from transistor gates connected to that node.  If the .sim file was produced by
	      ext2sim(1), check the technology file that was used to produce the original .ext files to see whether transistor gate capacitance is
	      included or excluded; see ``Magic Maintainer's Manual #2: The Technology File'' for details.

       R node res
	      Defines the lumped resistance of node node to be res ohms.  This construct is only interpreted by a few programs.

       r node1 node2 res
	      Defines an explicit resistor between nodes node1 and node2 of resistance res ohms.  This construct is only interpreted by a few pro-
	      grams.

       N node darea dperim parea pperim marea mperim
	      As an alternative to computed capacitances, some tools expect the total perimeter and area of the polysilicon, diffusion, and  metal
	      in  each	node to be reported in the .sim file.  The N construct associates diffusion area darea (in square centimicrons) and diffu-
	      sion perimeter dperim (in centimicrons) with node node, polysilicon area parea and  perimeter  pperim,  and  metal  area	marea  and
	      perimeter mperim.  This construct is technology dependent and obsolete.

       A node attr
	      Associates attribute attr for node node.	The string attr should contain no blanks.

       = node1 node2
	      Each  node  in  a  .sim file is named implicitly by having it appear in a transistor definition.	All node names appearing in a .sim
	      file are assumed to be distinct.	Some tools, such as esim(1), recognize aliases for node names.	The = construct  allows  the  name
	      node2  to be defined as an alias for the name node1.  Aliases defined by means of this construct may not appear anywhere else in the
	      .sim file.

SEE ALSO

       crystal(1), esim(1), ext2sim(1), sim2spice(1), ext(5)

4th Berkeley Distribution														    SIM(5)