Net Labels, Ports & Ground

Ground

Place a ground symbol (Place ‣ Symbol…, then ground) on any node that is the circuit reference. Its net is always 0 — the SLiCAP / SPICE reference node.

Net labels

A net label gives a wire a readable name (in, out, vdd …) that is used in the netlist and shown on the drawing.

  1. Choose Place ‣ Net Label (shortcut L) and click the wire, or double-click a wire segment to open its net-label dialog.

  2. Type the name and choose whether to display it.

A net label on a wire

Fig. 30 A net label naming the output node out.

All wires that are electrically the same net share one name.

Ports

A port symbol marks a named connection point. Two ports with the same name are connected even when no wire runs between them, which keeps busy drawings readable. In a schematic saved as a subcircuit, the named ports are the external nodes of the block; see /GUI/hierarchical_blocks.

Parameter definitions

Use Place ‣ Parameters… to add a parameter table to the schematic — a list of name = value definitions (for example R_s = 825, C_L = 10e-12). These become .param lines in the netlist and are typeset as a neat table on the figure.

A parameter table

Fig. 31 A parameter table rendered on the schematic.

Designating source, detector and loop-gain reference

For a SLiCAP analysis you must say what is driving the circuit and where you observe it:

  1. Choose Place ‣ Define src / det / lg ref….

  2. Set the source (an independent source, e.g. V1), the detector (a node voltage or branch current, e.g. V_out) and, optionally, the loop-gain reference.

These are written as the corresponding SLiCAP commands in the netlist.

Important

Define the source, the detector and the loop-gain reference after the schematic is complete, and save it first. When the dialog opens, the schematic is saved to a netlist and parsed with makeCircuit(); the drop-down lists are filled from that parsed circuit. This is the only way to offer the names that exist after model expansion only, such as the loop-gain reference E_O1 inside an operational amplifier O1. Elements you add or rename afterwards are not in the lists until you reopen the dialog, and an unsaved or incomplete schematic gives empty lists; you can still type a name by hand. Editing the block later, through the same menu entry or by double-clicking it, refreshes the lists.

Checking of the circuit make take some time. You may have to wait a few seconds before this dialog window pops up.