Node Sets (nodeset)

Description

The nodeset statement is used to provide an initial guess for nodes in DC analysis or to provide the initial condition calculation for transient analysis. The nodeset statement can occur multiple times in the input and the information provided in all the occurrences is collected. For more information, read the description of DC analysis.

Definition

nodeset <X>[:param]=value

This statement takes a list of signals with the state information to the DC and transient analyses. X can be a node, a component, or a subcircuit, and param can be either a component output parameter or a terminal index. To specify a class of signals, use the pattern matching character * for any string and ? for any character.

The concept of nodes for the statement has been generalized to signals, where a signal is a value associated with a topological node of the circuit or some other unknown that is solved by the simulator, such as the current through an inductor or the voltage of the internal node in a diode. Topological nodes can be either at the top-level or in a subcircuit.

For example:

nodeset 7=0 out=1 OpAmp1.comp=5 L1:1=1.0u

where, 7=0 implies that node 7 should be about 0V, node out should be about 1V, node comp in subcircuit OpAmp1 should be about 5V, and the current through the first terminal of L1 should be about 1uA.

For more information, refer to The ic and nodeset Statements in the Spectre Classic Simulator, Spectre APS, Spectre X, and Spectre XPS User Guide.