xschem/xschem_library/analyses

Visual simulation setup library

This library makes it possible to set up simulations in a way similar to that in Qucs. Each analysis is represented by a symbol. Symbols (e.g. op.sym, ac.sym, ...) have attributes that specify the analysis parameters. The instances of these symbols are netlisted as commands in the control block of VACASK/Ngspice. The ordering is specified by the order attribute. If order is not set, 0 is assumed. The symbols (blocks) are netlisted in the ascending order.

Each block displays only those attributes that are specified (i.e. the string length is>0). Netlisting is triggered by the command_block.sym block. In order for the netlister to generate the control block you have to place it in the schematic exactly once. In order for netlisting to work you have to source the analyses.init.tcl script at Xschem startup by adding the following line to xschemrc.

source analyses.init.tcl

An example that demonstrates the capabilities of this library is in file demo.sch.

Setting up sweeps

A sweep is defined with an instance of the sweep.sym block. Each sweep has a name and a tag attribute. The tag is the name of the variable that will hold the swept values in the simulator's output file (applies only to VACASK). The name of the sweep is the one you have to refer to in an analysis to make sweep that particular analysis. To sweep an analysis set its sweep parameter to the name of the sweep that applies to that analysis. Each sweep.sym instance has a sweep parameter. This parameter makes it possible to chain sweeps and form multidimensional sweeps.

For Ngspice sweeps are supported only for the operating point analysis where they are limited to a maximum of 2 dimensions.

Available analyses

The following analyses are supported

Symbol	VACASK	Ngspice
op.sym	op	op
dc1d.sym	1D sweep of op	dc (1D)
dcinc.sym	dcinc	-
dcxf.sym	dcxf	tf
ac.sym	ac	ac
acxf.sym	acxf	-
noise.sym	noise	noise
tran.sym	tran	tran
hb.sym	hb	-

Verbatim blocks

To put verbatim text in a control block the verbatim.sym block can be used. The simulator attribute specifies the simulator for which the block will be netlisted. If the attribute is not specified the block is netlisted for all simulators. The contents of the block are specified by the verbatim attribute.

Postprocessing scripts

Postprocessing scripts can be invoked with instances of the the postproc.sym block. The tool attribute specifies the (double-quoted) external program to invoke. The file attribute specifies the (double-quoted) name of the file that will be passed to the tool. If unquoted PYTHON is specified as the tool the python3 interpreter is invoked under Linux and python.exe is invoked under Windows.