Netlist & Export

A finished schematic produces three things: a netlist for analysis, and SVG / PDF figures for documents.

From the GUI

• File ‣ Export netlist… (Ctrl+E) writes the netlist to cir/: .cir for a SLiCAP circuit, .sp for an NGspice circuit. For a subcircuit schematic it writes the subcircuit library to lib/ instead, <title>.slicap_lib or <title>.spice_lib, the same file as the headless export and as saving the subcircuit.

• File ‣ Export SVG… writes a vector figure.

• File ‣ Export PDF… writes a PDF figure.

• File ‣ Print schematic… (Ctrl+P) prints the drawing.

Fig. 34 The schematic and the netlist it produced, side by side.

From the command line

The same outputs can be generated without opening the window — useful for build scripts and Makefiles:

$ python -m SLiCAP.schematic.cli netlist  sch/my_circuit.slicap_sch
$ python -m SLiCAP.schematic.cli svg      sch/my_circuit.slicap_sch
$ python -m SLiCAP.schematic.cli pdf      sch/my_circuit.slicap_sch

If -o <file> is omitted, the output takes the schematic’s name with the appropriate extension and lands in the project’s cir/ (netlist) or img/ (SVG / PDF) directory automatically. For a schematic saved as a subcircuit the netlist command writes the library lib/<name>.slicap_lib instead of a .cir file (see Hierarchical Blocks).

Running it in SLiCAP

makeCircuit() recognises the .slicap_sch extension and generates the netlist and figures automatically before parsing:

import SLiCAP as sl
sl.initProject("My Design")
cir = sl.makeCircuit("sch/my_circuit.slicap_sch")   # exports + parses
result = sl.doNoise(cir, pardefs="circuit", numeric=True)

The export can also be run on its own with sl.updateImages(), which rewrites the schematic’s images (and its netlist) without creating a circuit object. It takes the circuit object of a SLiCAP schematic, or the name of the circuit, which is how an NGspice schematic is addressed. Its place is the end of the instruction file. A schematic that links plots (Place ‣ Image… with a file in img/) inlines them at export time, and makeCircuit() at the top of the file exports before the analyses have written them. An export after the figures shows the plots of this run:

cir = sl.makeCircuit("sch/my_circuit.spice_sch")   # exports + parses
TR1 = sl.tran("my_circuit", "1n", "1u")
FIG1 = sl.makeFigure([[AX1]], "tran")               # writes img/tran.svg
sl.updateImages("my_circuit")                       # exports with the new plot

Instruction ‣ Update schematic images… on the schematic’s tab appends that last line. Both calls skip the export when the netlist and the images are newer than everything they depend on: the schematic, its sidecars, the symbol libraries, the operating-point results and the linked images. On the canvas the linked images are reloaded after every run.

For a subcircuit schematic both calls write the library in lib/ and the figures, and makeCircuit() returns None: a subcircuit dos not require a ground node 0 and is not parsed as a circuit.

sl.makeCircuit("lib/smallAmp.slicap_sch")   # writes lib/smallAmp.slicap_lib and img/smallAmp.svg, .pdf

What the netlist looks like

The first line is the title.

Each element becomes one line — reference designator, nodes (in the symbol’s node order), any references, the model and the parameters:

"My Circuit"

.param R_s = 825
.param C_L = 10e-12

.source V1
.detector V_out

R1 in 3 R value={R_s}
N1 out 0 in 1 N
C3 out 0 C value={C_L}
...
.end