Setup

1. Set the following path variable to wherever this repo is cloned to in KiCAD under "Preferences" -> "Configure Paths": KICAD_SIMULATION_LIB_DIR

   e.g.: Name: KICAD_SIMULATION_LIB_DIR Path:/home/$USER/Documents/Kicad/Simulation_libraries

Library conventions

• To make a new symbol:

  • Create one with following options checked in the symbol properties:

    • Exclude from schematic bill of materials
    • Exclude from board

  • Edit the Spice model to link the symbol with the model and:

    • Make Spice_Lib_File relative to $(KICAD_SIMULATION_LIB_DIR), since it is first generated as absolute path (not portable to other machines)
      • E.g. Name: Spice_Lib_File Value: $(KICAD_SIMULATION_LIB_DIR)/ngspice-lib/integrator/integrator.lib

  • Make only the following fields visible:

    • Reference (e.g. "X")
    • Spice_Model (e.g. "CCCS g=1")

• Usage

  • Pass subcircuit parameters right after the model name as the value of Spice_Model
    • E.g. passing initial condition to the integrator's output Name: Spice_Model Value: INTEGRATOR ic=10

Example

Ngspice model definition (file: ngspice-lib/pwm_generator/pwm_generator.lib)

** input nodes:
*           ||=============>signal: arbitrary voltage signal to be
*           ||                      modulated (e.g. sine wave)
*           ||     ||======>freq: carier voltage given as a voltage value
*           ||     ||   ||=>output: PWM output signal
.subckt PWM3 signal freq output

BsawtoothP      sawtoothP       gnd     v=0.5+(time*v(freq)-floor(0.5+time*v(freq)))
BsawtoothM      sawtoothN       gnd     v=-0.5+(time*v(freq)-floor(0.5+time*v(freq)))
Bpwm            output          gnd     v=v(signal)>=v(sawtoothP) && v(signal)>=0 ? 1 : v(signal)<=v(sawtoothN) && v(signal)<=0 ? -1 : 0

.ends PWM3

Symbol creation and model linking

Usage of symbol with embedded spice model