Basics

A schematic is a graphical display of an electrical circuit. It is designed in a way that it is easy understandable with the human eyes. It is not designed to be easy readable for machines and computer software. Most electrical simulator cannot work with graphical schematics and need a text based netlist as input. A netlist concentrates all relevant information of a schematic as simple text. A wide range of different netlist formats exist. There is not a general standard format supported by all tools. But most simulators support a handful different netlist formats.

Using defined Netlist Formats

A text based netlist can be automatically created from a graphical schematic. Once the setup is done, netlist generation from a schematic can be simply done by using the SaveAs feature. Alternatively the generated netlist can be displayed in the included TextEditor by calling the related menu entry. The SchematicEditor comes with a setup for some common netlist formats. While it's possible for a netlist to be generated without any setup, some smaller adjustments are often required. To perform these adjustments you need to understand the way the netlist is generated.

Generating Netlists - Concept

A netlist concentrates all relevant information of a schematic. This includes a description of its components and how the components are connected. Netlists for simulations also include information about what and how to simulate the circuit. The first step for a netlist generation is the extraction of a list of all components and its connections. This information will be added to a netlist template in a formal way. All existing templates for different netlist formats can be viewed and edited via the SetupDialog. New formats can be easily added. A typical netlist template looks like this:

*spice $filename export from LayoutEditor

$groundnode(0)

*start of netlist
$netlist(spice)
*end of netlist

*required models
$model(spice)

The formal netlist generation works this way: Any expression starting with '$' from the template definition is evaluated and passed to the resulting netlist. For example, $filename will be replaced by the actual filename from which the netlist was extracted. $netlist(type) will be replaced by a list of all components in the schematic. The output formatting specified by type is used for each component. Expression containing a '$' in that component output will be replaced as well. So that the above shown definition may result in a netlist like this:

*spice layout/example/doubler/doubler.les export from LayoutEditor

*start of netlist
XU3 VSS VDD 2 4 INV_X1
XU2 VSS VDD 3 2 INV_X1
XU1 VSS VDD IN 3 INV_X1
XU4 VSS VDD IN 4 OUT AND2_X1
*end of netlist

*required models
.include layout/library/openCellLibrary/spicemodel.sp

The component specific netlist information is stored with each component. With the Edit Component feature you can define unlimited different netlist information for any component. The information is split into the pure netlist information which is listed once for each component in the schematic and a model information which is listed once for each type of the component. Exporting the netlist is done via the save as feature in the schematic or can be viewed via the utilities menu. The netlist body is defined in the setup dialog of the LayoutEditor as explained in the previous section.

Generating Netlists - Reference

An overview of all supported expression in a netlist:

Global Expressions

Sheet Expressions

Port/Node specific Expressions

Component specific Expressions

Commands

Example for changing command characters:

$commandChar(@)
@parameterStartChar({)
@parameterEndChar{})
@parameterSeparationChar{:}

*new command will look
@netlist{spice}
*no longer working: $netlist(spice)