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Stable release
ngspice-35 / Aug 8th, 2021
Written inC
PlatformLinux, Windows, macOS, BSD, others
Available inEnglish
TypeElectronic circuit simulation

Ngspice[1][2][3] is a mixed-level/mixed-signal electronic circuit simulator. It is a successor of the latest stable release of Berkeley SPICE, version 3f.5, which was released in 1993. A small group of maintainers and the user community contribute to the ngspice project by providing new features, enhancements and bug fixes.

Ngspice is based on three open-source free-software packages: Spice3f5, Xspice and Cider1b1:

  • SPICE[4] is the origin of all electronic circuit simulators, its successors are widely used in the electronics community.
  • Xspice[5] is an extension to Spice3 that provides additional C language code models to support analog behavioral modeling and co-simulation of digital components through a fast event-driven algorithm.
  • Cider[6] adds a numerical device simulator to ngspice. It couples the circuit-level simulator to the device simulator to provide enhanced simulation accuracy (at the expense of increased simulation time). Critical devices can be described with their technology parameters (numerical models), all others may use the original ngspice compact models.


Ngspice implements three classes of analysis:

  • Nonlinear DC analyses
  • Nonlinear transient analyses
  • Linear AC analyses

Transient analysis includes transient noise simulation. AC analysis includes small-signal noise simulation, pole-zero and transfer function analysis.

Ngspice implements various circuits elements, like resistors, capacitors, inductors (single or mutual), transmission lines and a growing number of semiconductor devices like diodes, bipolar transistors, MOSFETs (both bulk and SOI), MESFETs, JFETs and HFETs.

New models can be added to the simulator using:

  • Behavioral modeling: Internal B-, E-, and G-sources, as well as R, C and L devices, offer modeling by mathematical expressions, driven by node voltages, branch currents, parameters and constants.
  • The Xspice codemodel interface: This is a C-code interface that helps the modeling process by simplifying the access to simulator's internal structure.
  • ADMS verilog model compiler: The ADMS model compiler generates C code from Verilog-A model descriptions for integration into ngspice.
  • C language coded models with spice format: As an open-source project, Ngspice allows new models to be linked to the sources and compiled.

Ngspice supports parametric netlists (i.e. netlists can contain parameters and expressions). PSPICE compatible parametric macromodels, often released by manufacturers, can be imported as-is into the simulator. Polynomial sources are available. Ngspice provides an internal scripting language to facilitate complex simulation and evaluation control flows.

Ngspice may be compiled into a shared library (*.dll or *.so) readily to be integrated into a calling program. Its interface provides access to all simulation parameters, input and output data. tclspice, another shared library version, offers an interface to Tcl/Tk (software).

Ngspice is licensed under the BSD-3-Clause license. This permissive open source license allows its integration as a simulation engine into several — proprietary or free/libre — EDA tools such as KiCad,[7][8] EAGLE (program),[9] CoolSPICE, Altium and others.

Ngspice has a command line input interface and offers plotting capability. An open source GUI with schematic entry, simulation and plotting is provided by Qucs-S.

Recent progresses on Ngspice have been presented at conferences such as FOSDEM [10] and FSiC.[11]

See also[edit]


  1. ^ NGSPICE: recent progresses and future plans, P. Nenzi e.a., MOS-AK, Bucharest 2014,
  2. ^ The NGSPICE circuit simulator, P. Nenzi e.a., FOSDEM, Brussels 2015,
  3. ^ ngspice, current status and future developments, H. Vogt, FOSDEM, Brussels 2019,
  4. ^ Analysis of Performance and Convergence Issues for Circuit Simulation, T. Quarles, PhD dissertation, Memorandum No. UCB/ERL M89/42, Berkeley 1989,
  5. ^ Code-level modeling in XSPICE, F. L. Cox e.a., Proceedings IEEE International Symposium on Circuits and Systems, 1992 (ISCAS 92), vol. 2, pp. 871-874, 10–13 May 1992
  6. ^ CODECS: A Mixed-Level Circuit and Device Simulator, K. Mayaram, Memorandum No. UCB/ERL M88/71, Berkeley, 1988,
  7. ^ "Tutorial: how to set up ngspice and Eeschema for KiCad". ngspice. Retrieved 2019-07-18.
  8. ^ Integrated Spice Simulation with Kicad, T. Wlostowski, FOSDEM, Brussels 2017,
  9. ^ SPICE Simulation Part 1, S. Sattel, Autodesk Support and Learning, 2017,
  10. ^ "ngspice, current status and future developments". Free and Open source Software Developers' European Meeting (FOSDEM). Retrieved 2019-06-25.
  11. ^ "ngspice - an open source mixed signal circuit simulator". Free Silicon Foundation (F-Si). Retrieved 2019-06-25.

External links[edit]