EXT2SIM(1)

✨ EXT2SIM ✨

okay bestie, gather round, because this one is literally the glow-up machine for your circuit files 💖 It's ext2sim, a General Commands Manual page, and it takes your hierarchical ext(5) extracted-circuit files and turns them into flat sim(5) files. No cap. Let's go 🦋

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🌸 SYNOPSIS 🌸

ext2sim [ -a aliasfile ] [ -l labelsfile ] [ -o simfile ] [ -A ] [ -B ]
[ -F ] [ -L ] [ -t ] [ extcheck-options ] [ -y num ] [ -f mit|lbl|su ] [
-J hier|flat ] [ -j device:sdRclass[/subRclass]/defaultSubstrate ] root

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💅 DESCRIPTION 💅

So here's the tea, bestie. ext2sim takes an extracted circuit in the hierarchical ext(5) representation (the one Magic makes for you 👑) and converts it to the flat sim(5) representation that, like, a ton of simulation tools need. Glow-down, honestly.

The root of the tree you're extracting is the file root.ext, and it plus every file it references gets recursively flattened. Then you get a single, flat representation of the circuit, and it lands in three places:

• root.sim — the flat circuit itself ✨
• root.al — a list of node aliases
• root.nodes — a list of the locations of all nodenames in CIF format, suitable for plotting

That root.sim file is ready to vibe with programs like crystal(1), esim(1), or sim2spice(1). Iconic.

The following options are recognized:

🎀 OPTIONS 🎀

• -a aliasfile — instead of leaving node aliases in the file root.al, leave them in aliasfile. Moving house, but for aliases.
• -l labelfile — instead of leaving a CIF file with the locations of all node names in the file root.nodes, leave it in labelfile. Same energy.
• -o outfile — instead of leaving output in the file root.sim, leave it in outfile. Yes, you can name it whatever, go off 💜
• -A — don't produce the aliases file. At all. It's giving minimalism.
• -B — don't output transistor or node attributes in the .sim file. This option will also disable the output of information such as the area and perimeter of source and drain diffusion and the fet substrate. For compatibitlity reasons the latest version of ext2sim outputs this information as node attibutes. This option is necessary when preparing input for programs that don't know about attributes, such as sim2spice(1) (which is actually made obsolete by ext2spice(1), anyway), or rsim(1). (Yes bestie, those typos are in the original, I am not touching them, they're part of the lore 🙈)
• -F — don't output nodes that aren't connected to fets (floating nodes). Bye to the unconnected girlies 👋
• -L — don't produce the label file.
• -tchar — trim characters from node names when writing the output file. char should be either # or !. The option may be used twice if both characters are desired. Double it up, it's fine 💅
• -f MIT|LBL|SU — select the output format:
  • MIT is the traditional sim(5) format.
  • LBL is a variant of it understood by gemini(1) which includes the substrate connection as a fourth terminal before length and width.
  • SU is the internal Stanford format which is described also in sim(5) and includes areas and perimeters of fet sources, drains and substrates.
• -y num — select the precision for outputing capacitors. The default is 1 which means that the capacitors will be printed to a precision of .1 fF. Slay, that's precise 💖
• -J hier|flat — select the source/drain area and perimeter extraction algorithm. Let's break it down:
  • If hier is selected, then the areas and perimeters are extracted only within each subcell. For each fet in a subcell, the area and perimeter of its source and drain within this subcell are output. If two or more fets share a source/drain node, then the total area and perimeter will be output in only one of them and the other will have 0.
  • If flat is selected, the same rules apply only that the scope of search for area and perimeter is the whole netlist. In general flat (which is the default) will give accurate results (it will take into account shared sources/drains) but hier is provided for backwards compatibility with version 6.4.5.
  • On top of this selection you can individually control how a terminal of a specific fet will be extracted if you put a source/drain attribute. ext:aph makes the extraction for that specific terminal hierarchical and ext:apf makes the extraction flat (see the magic tutorial about attaching attribute labels). Additionaly to ease extraction of bipolar transistors the gate attribute ext:aps forces the output of the the substrate area and perimeter for a specific fet (in flat mode only).
• -j device:sdRclass[/subRclass]/defaultSubstrate — gives ext2sim information about the source/drain resistance class of the fet type device. Makes device to have sdRclass source drain resistance class, subRclass substrate (well) resistance class and the node named defaultSubstrate as its default substrate. The defaults are nfet:0/Gnd and pfet:1/6/Vdd which correspond to the MOSIS technology file but things might vary in your site. Ask your local cad administrator. (fr fr, they know things 👑)

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The way the extraction of node area and perimeter works in magic, the total area and perimeter of the source/drain junction is summed up on a single node. That is why all the junction areas and perimeters are summed up on a single node (this should not affect simulation results however).

⚠️ Special care must be taken when the substrate of a fet is tied to a node other than the default substrate (eg in a bootstraping charge pump). To get the correct substrate info in these cases the fet(s) with separate wells should be in their own separate subcell with ext:aph attributes attached to their sensitive terminals (also all the transistors which share sensistive terminals with these should be in another subcell with the same attributes).

In addition, all of the options of extcheck(1) are accepted. Yes, all of them. The whole buffet 🍓

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🌈 SCALING AND UNITS 🌈

If all of the .ext files in the tree read by ext2sim have the same geometrical scale (specified in the scale line in each .ext file), this scale is reflected through to the output, resulting in substantially smaller .sim files. Cute and efficient ✨

Otherwise, the geometrical unit in the output .sim file is a centimicron.

Resistance and capacitance are always output in ohms and femptofarads, respectively. Non-negotiable 💅

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🦋 SEE ALSO 🦋

extcheck(1), ext2dlys(1), ext2spice(1), magic(1), rsim(1), ext(5), sim(5)

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🎀 AUTHOR 🎀

Walter Scott additions/fixes by Stefanos Sidiropoulos.

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💀 BUGS 💀

Transistor gate capacitance is typically not included in node capacitances, as most analysis tools compute the gate capacitance directly from the gate area. The -c flag therefore provides a limit only on non-gate capacitance.

The areas and perimeters of fet sources and drains work only with the simple extraction algorith and not with the extresis flow. So you have to model them as linear capacitors (create a special extraction style) if you want to extract parasitic resistances with extresis. Not me finding out the hard way 😭

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This page came to you from the 4th Berkeley Distribution, dated like the legend it is, and it's the EXT2SIM(1) manual page itself. Mwah. Stay flat, stay slayed 💖✨🫶