The Electrical Circuit (cir) interface (), found under the AC/DC branch () when adding a physics interface, is used to model currents and voltages in circuits including voltage and current sources, resistors, capacitors, inductors, and semiconductor devices. Models created with the Electrical Circuit interface can include connections to distributed field models. The physics interface supports stationary, frequency-domain and time-domain modeling and solves Kirchhoff's conservation laws for the voltages, currents and charges associated with the circuit elements.

When this physics interface is added, it adds a default Ground Node feature and associates that with node zero in the electrical circuit.

Each circuit component has an associated Device name, which is constructed from a prefix identifying the type of the device and a string. The string can be specified in the feature’s Settings window. The Device name is used to identify variables defined by the component, and for the SPICE Import and Exportfunctionality.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is cir.

For numerical stability, a large resistance is added automatically in parallel to the pn junctions in diodes and BJT devices. Enter a default value for the Resistance in parallel to pn junctions Rj (SI unit: Ω). The default value is 1·1012 Ω.

The following nodes are available from the Electrical Circuit ribbon toolbar (Windows users), Electrical Circuit context menu (Mac or Linux users), or right-click to access the context menu (all users).: