ngspice – open source spice simulator, ngspice is the open source spice simulator for electric and electronic circuits.
Such a circuit may comprise of JFETs, bipolar and MOS transistors, passive elements like R, L, or C, diodes, transmission lines and other devices, all interconnected in a netlist. Digital circuits are simulated as well, event driven and fast, from single gates to complex circuits. And you may enter the combination of both analog and digital as a mixed-signal circuit.
ngspice offers a wealth of device models for active, passive, analog, and digital elements. Model parameters are provided by the semiconductor manufacturers. The user add her circuits as a netlist, and the output is one or more graphs of currents, voltages and other electrical quantities or is saved in a data file.
ngspice does not provide schematic entry. Its input is command line or file based. There are however third party interfaces available.
ngspice is SPICE compatible. You may apply PSPICE or LTSPICE device model parameters and netlists for simulating discrete circuits. ngspice will also read HSPICE device libraries from semiconductor foundry PDKs for simulating integrated circuits.
ngspice builds on many operating systems. The source code and binaries for MS Windows and macOS are available for download on our sourceforge download page. All popular Linux distributions, Cygwin or FreeBSD offer ngspice as well. The F.A.Q. and documentation pages provide a lot of information, a detailed manual is available