MacSpice for Mac

From Charles D.H. Williams:

MacSpice simulates and analyses electronic circuits that can range in complexity from a single resistor to an integrated circuit comprising tens-of-thousands of devices. It has users who range in experience from school-age enthusiasts to retired integrated circuit designers. It is used at various universities internationally for research and teaching.

Circuit simulation is a way of building and testing virtual models of electronic devices. It is usually cheaper and quicker to simulate a design than to build a prototype. MacSpice, like most circuit simulators, requires a text-file description of the circuit as input. This 'netlist' is a list of components and the nodes they connect to. Users may prepare netlists with a text editor, or derive them from a circuit diagram using a third-party schematic-capture application. MacSpice then builds a numerical model of the circuit and analyses this.

A command interpreter (shell) is used to specify the types of analyses that are required and how the results should be processed, saved or displayed. The high quality of the MacSpice command interpreter makes the automation of tasks straightforward.

Simulation is a tool, not a magic-wand. The quality of the results depends on the accuracy of the netlist and the device models use. Within Spice most devices are ideal - its resistor, for example, has just one property: resistance. A real resistor has parasitic inductance and capacitance; if these have a significant influence on the circuit, they must be added explicitly to the netlist.