Electronics Design Automation - KiCad SPICE Modeling
BME254L - Spring 2026
Electronics Design Automation: SPICE Modeling
What is SPICE?
Simulation Program with Integrated Circuit Emphasis (SPICE)
Model and analyze the behavior of electronic circuits before they are physically constructed.
Input schematic representations of circuits (e.g., resistors, capacitors, transistors, diodes, etc.)
Simulate circuit performance by computing current, voltage, and power, across these components under different conditions.
Why model circuits?
Reduce design costs.
Breadboards / thru-hole prototyping is not realistic for complex circuits.
Most components are now surface mount.
Model \(\rightarrow\) Breakout Boards \(\rightarrow\) PCB
SPICE vs. Non-SPICE Components
SPICE components are defined by their mathematical models.
Non-SPICE components are defined by their physical characteristics.
KiCad has a library of SPICE models for common components.
SPICE models are not always available for all components, but can be downloaded and added to some libraries.
SPICE models can be edited / created for custom components.
Limiting Scope of SPICE Simulation
We usually want to simulate as simple of a circuit as possible.
We can limit the scope of the simulation by excluding components from the braoder schematic from the sub-circuit that we want to simulate:
Drag select all of the components you want to exclude to highlight them.
Right Click:
Attributes -> Exclude from SimulationRepeat this for other sheets / circuits in the schematic.
In the Simulation window, Confirm that your
SPICE Netlistreflets what you actually want to simulate.
Setting Component Simulation Parameters
The SPICE model can be set in the component properties.
The component must have a SPICE model to be included in the simulation.
Only certain components allow certain simulation parameters to be varied (e.g., resistors vs. potentiometers).
Setting Analysis Parameters
AC Sweep: frequency analysis
DC Sweep: sweep voltage, current, resistance, capacitance
Operating Point: analysis at a specific point in time
Transient: time-domain analysis
Run Simulation and Probe Components
Simulations are
Run(Blue Arrow in Simulation window).Probes can be added by parameter and component name or interactively.
Choose a
New Analysisand what components you want to sweep.- Avoid setting any values to
0as they can cause numerical instability!
- Avoid setting any values to
After you hit
Ok, choose the parameters from the right side of the window that you would like to plot.If you change your schematic, be sure to re-Run the simulation.
- You may want to create a new analysis tab to make sure that the simulation reflects the latest changes.
All open analysis tabs must be valid for the running simulation to be successful!