Analog Computing Elements for LTspice

A library of archetypal analog computing elements for rapid analog circuit prototyping in LTspice.

About • Key Features • Quick Start • Learn More

Adding a summer element to complete an analog circuit for a simple one-dimensional oscillator.

About

This library provides a complete set of LTspice-compatible analog computing elements – integrators, summers, multipliers, dividers, log/antilog blocks, and more – packaged as reusable components. Instead of hand-drawing op-amp circuits and updating values by hand, you work with high-level computing primitives that are parameterised via SPICE directives and designed for hierarchical, modular analog computing systems.

The elements are available at three abstraction levels (numerical, ideal-component, and real-component), letting you move smoothly from pure mathematical models to realistic circuit implementations using actual SPICE device models.

Key Features

• Complete element set – Integrators, summers, multipliers, dividers, log/antilog, differentiators, buffers, and more
• Three simulation levels – Numerical, ideal-component, and real-component implementations for different design stages
• Parameterised design – Configure behaviour using SPICE parameters (e.g., time constants, gains, scaling factors)
• Hierarchical and modular – Build complex systems from reusable computing subcircuits
• Batch and scripting friendly – Works well with LTspice batch modes and tools like PyLTSpice
• Cross‑platform – Compatible with any platform that runs LTspice

Quick Start

1. Clone or download this repository.
2. Run the make script: ./make.py or python3 make.py.
3. Copy the contents of the generated all directory into your LTspice project directory.
4. In LTspice, open (or create) a schematic and press F2 to open the component picker.
5. Set your project directory as the top directory and place the desired computing elements.
6. Wire elements together and add SPICE directives (e.g. .tran) as you would in any LTspice schematic.

For example schematics demonstrating all elements, and for detailed installation notes (including Windows-wide installation), see DOCUMENTATION.md.

Learn More

For full documentation, including:

• Detailed descriptions of each computing element and its transfer function
• Explanations of the numerical / ideal / real simulation types
• Example circuits (testbench and simple oscillator)
• Parameterisation and simulation tips
• Troubleshooting guidance for convergence and timestep issues

See DOCUMENTATION.md.

Status

This project is stable but not under active development. It may receive occasional updates (for example, additional computing elements) but there are no concrete plans.

License

This project is licensed under the CC BY-NC-SA 4.0 License.