NGSpice

NGSpice is an open-source mixed-level/mixed-signal electronic circuit simulator based on SPICE (Simulation Program with Integrated Circuit Emphasis). It is widely used for simulating analog, digital, and mixed-signal circuits, making it a versatile tool for circuit design and analysis.

NGSpice provides accurate simulation of circuit behavior through transient, AC, DC, and noise analysis, supporting both time-domain and frequency-domain evaluations. It is compatible with standard SPICE models, allowing users to simulate complex components like transistors, diodes, and operational amplifiers. The tool can be integrated into larger EDA workflows and is supported by many circuit design programs, including KiCad.

Its open-source nature makes NGSpice highly customizable and freely available to hobbyists, researchers, and professionals for tasks ranging from simple circuit validation to advanced semiconductor device analysis.