interpolationMethod

cfde.spectre interpolationMethod cyclic { "default" | "linear" | "spline" | "bbspice" }

Description

Specifies the interpolation method to be used by Spectre when simulating S-parameter data specified in the nport. The value of this variable is reflected in the Interpolation Method field of the Edit Properties form for the modeled device.

Possible Values:

• linear: Uses linear interpolation to get a data point needed in the sample that is not directly in the S-parameter file.
  
  If the S-parameter file represents an active device, specify "linear" interpolation, instead of "default" or "bbspice" because "bbspice" enforces passivity.
• spline: Uses a cubic spline algorithm. Cubic spline can occasionally introduce errors when there are rapid changes in the transfer functions defined in the S-parameter file near the sample point.
• bbspice: Uses a rational model to represent the S-parameter data. This method is used to do a rational fit.
• default: Allows Spectre to automatically use an interpolation method. Spectre uses the default value for the interp option of an nport according to the Spectre global option nport_default_interp. When nport_default_interp is set to auto_switch, the nport automatically switches the interpolation method depending on the analysis. It chooses bbspice for the pss shooting Newton analysis, and linear for other analyses, such as ac, dc, and sp.
  If an nport instance has the interp option explicitly specified, the value of interp for that instance takes priority over the global option nport_default_interp. For all nport instances in the netlist that do not have interp set explicitly, they use the value specified in nport_default_interp.

Default value: default

GUI Equivalent

None

Examples

envGetVal("cfde.spectre" "interpolationMethod")

envSetVal("cfde.spectre" "interpolationMethod" 'cyclic "linear")

Related Topics

Interpolation Method in Analog Library Reference

Variables to Customize Extracted View Creation

Also see spectre -h nport for information on how nport_default_interp works for the version of Spectre you are using