ngspice: ngspice (mixed-level/mixed-signal circuit simulator) ngspice: ngspice: Ngspice is a mixed-level/mixed-signal circuit simulator. Its code is ngspice: based on three open source software packages: Spice3f5, Cider1b1 and ngspice: Xspice. Ngspice is part of gEDA project, a full GPL'd suite of ngspice: Electronic Design Automation tools. ngspice: ngspice: ngspice: ngspice: ngspice: