Spice Simulation

Add a small ngspice-backed testbench to a

.zen

design.

Workflow

Confirm the target is simulation-capable by runnnig a dummy sim.
```
pcb sim <path/to/file.zen> --setup "* empty setup check"
```
If the SPICE model is missing, add it. Find a vendor model, download it, or create a simple behavioral model if needed. Wire it through the leaf component with
```
spice_model=SpiceModel(...)
```
before writing the testbench.
Create a focused testbench file. Use a generic package-local path such as
```
<package>/testbench/test_<scenario>.zen
```
.
Keep the structure simple:

top docstring
imports
nets/interfaces
module-under-test instantiation
minimal external load or pull-ups
one
```
Simulation(...)
```
block

Put sources and analysis inside
```
Simulation.setup
```
. Use raw ngspice for:

```
DC
```
```
PULSE(...)
```
```
PWL(...)
```
```
.control
```
```
tran
```
```
hardcopy
```

Write the plot to
```
testbench/output/<scenario>.svg
```
.

Simulation In Zener

Simulation

is a Zener property loaded from

@stdlib/properties.zen

and attached as a normal top-level object:

python

load("@stdlib/properties.zen", "Simulation")

Simulation(
    name="SIM",
    setup="""
* raw ngspice goes here
.control
  tran 10u 10m
.endc
""",
)

The

setup

string is passed through as ngspice input. Put voltage sources, waveform definitions, analysis commands, and plot/export commands there.

Pattern

python

"""<Part> <scenario> simulation test."""

load("@stdlib/interfaces.zen", "Ground", "Power")
load("@stdlib/units.zen", "Voltage")
load("@stdlib/properties.zen", "Simulation")

Target = Module("../Target.zen")
Resistor = Module("@stdlib/generics/Resistor.zen")

VIN = Power("VIN", voltage=Voltage("12V"))
VOUT = Power("VOUT")
GND = Ground("GND")

Target(
    name="UUT",
    VIN=VIN,
    VOUT=VOUT,
    GND=GND,
)

Resistor(
    name="R_LOAD",
    value="10ohm",
    package="0603",
    P1=VOUT,
    P2=GND,
)

Simulation(
    name="SIM",
    setup="""
* <Part> <scenario>

V_IN VIN GND DC 12

.control
  tran 10u 10m

  set hcopydevtype = svg
  hardcopy output/<scenario>.svg v(VIN) v(VOUT) title "<Part> <scenario>" xlabel "Time" ylabel "Voltage"
.endc

""",
)

Component Pattern

If the leaf component does not already expose a SPICE model, add one like this:

python

VIN = io("VIN", Net)
VOUT = io("VOUT", Net)
GND = io("GND", Net)

Component(
    name="MyPart",
    symbol=Symbol(library="MyPart.kicad_sym"),
    pins={"VIN": VIN, "VOUT": VOUT, "GND": GND},
    spice_model=SpiceModel(
        "MyPart.lib",
        "MyPart_SUBCKT",
        nets=[VIN, VOUT, GND],
        args={},
    ),
)

Example Shapes

Load switch enable test:

spice

V_IN VIN GND DC 5.3
V_ON ON GND PULSE(0 0.9V 1ms 10us 10us 3ms 5ms)

Protection threshold sweep:

spice

V_IN VIN GND PWL(0 12 5m 12 5.1m 22 10m 22 10.1m 12 15m 12 15.1m 2 20m 2)

Notes

Prefer one behavior per file: startup, enable/disable, OVLO/UVLO, current limit.
Keep passives in Zener and keep sources in
```
setup
```
.
Plot only the signals that prove the behavior.
If a SPICE model is missing, obtain or create it first, then add the testbench.

spice-sim

NPX Install

Tags

SKILL.md Content

Spice Simulation

Workflow

Simulation In Zener

Pattern

Component Pattern

Example Shapes

Notes