ArbitraryCurve()

The syntax of the ArbitraryCurve() function has the following syntax with the arguments explained in the table below:

ArbitraryCurve(vector_expression, vectors_to_keep, curve_name, graph_name, grid_index, axis_name, OPTIONAL_PARAMETER_STRING)

Example 1

Suppose a node out is the output of an op-amp and its voltage is plotted with a fixed probe on a graph named DVM Output.

The following call to the ArbitraryCurve() function will plot the slew rate of the op-amp output on a new grid above the default grid.

ArbitraryCurve(1u*diff(out), out, DVM Slew Rate, DVM Output, A2, slew rate, yUnits=V/us)

• The vector expression, 1u*diff(out), contains engineering notation as well as the vector function diff().
• The diff() function calculates the first derivative with respect to the reference vector of the supplied argument, namely out.
• With the scaling factor 1u, the graph output is in the units of V/us and the supplied optional parameter labels the vertical axis with V/us.
• For additional information about general options that can be set with the optional parameter string, see Optional Parameters.

Example 2

Suppose that, after a simulation run, you want to plot two vectors against each other in an X-Y plot. A simple example plots the forward current against the forward voltage of a MOSFET body diode.

The following call to the ArbitraryCurve() function will generate the XY plot on a new graph sheet named Forward Biased.

ArbitraryCurve(XY(-QDUT#D, #S - #D), QDUT#D #D #S, DVM SIMPLIS, Forward Biased, A1, vertical, xlabel=Body Diode Forward Voltage ylabel=Body Diode Forward Current)

• The vector_expression argument in this example is fairly complex, using the built-in SIMetrix vector function XY() to plot the two arguments (Y, X) against each other.
• The vectors_to_keep list contains the MOSFET drain current, as well as the drain and source voltage.
• The net names are fixed on the schematic by adding terminals with names S and D, and the resulting vectors from a SIMPLIS simulation are prefixed with a #.
• Finally, using the optional parameter string, the graph axes are given labels appropriate to the graph.

The following syntax rules apply to the OPTIONAL_PARAMETER_STRING  argument:

• The OPTIONAL_PARAMETER_STRING  value must not contain a comma.
• The OPTIONAL_PARAMETER_STRING  is parsed on the equal sign.
• Since the argument is parsed on the equal sign, the value itself must not contain an equal sign. For example, the following is an invalid entry:

  ylabel=Body Diode Forward Current Temp=-40

  In this case , the program would read this incorrectly as two optional parameters:
  • ylabel=Body Diode Forward Current
  • Temp=-40

Spaces in values are allowed as long as no spaces are on either side of the equal sign. Thee three examples below illustrate this:

• ylabel=Body Diode Forward Current: valid entry with no spaces around the equal sign
• ylabel =Body Diode Forward Current: invalid entry with space before equal sign
• ylabel= Body Diode Forward Current: invalid entry with space after equal sign

The following table lists the available formatting options for use in the OPTIONAL_PARAMETER_STRING argument.

Specifying a Color

You have three options for specifying the color for a curve:

• Color-name Alias
• Hexadecimal Color
• SIMetrix Sequence

Color-name Alias

color=color_name

Hexadecimal color

color=#rrggbb

You can specify any color for the curve by using a hexadecimal specification.

SIMetrix Sequence

color=SEQ:n

SIMetrix has eight default curve colors, starting with red, green, blue, etc.

To change and extend these colors to a maximum of 20 user-defined curve colors, follow these steps:

1. From the menu bar, select File ▶ Options ▶ Colour....
2. Double click a curve item in the list and then select another color from the palette, and click OK.

• The return value from this function is a real value with 0 indicating success and 1 indicating an error.
• Error messages are displayed in the command shell for each function call.