## Monte Carlo Analysis

Like parameter sweeps, Monte Carlo analysis can be run in conjunction with any tests. Just select the test you wish to perform from the Test tab, set up the test parameters as described in the individual tests, and click on the Monte Carlo tab to set up a Monte Carlo analysis.

To
set up a Monte Carlo analysis, click on the Monte Carlo Setup
button. This will bring up the following dialog box:

The number of runs (or number of times to randomly vary the chosen parameter) is set in the # Iterations box. For each run, a set of device parameters is assigned randomly according to the parameter's range and distribution type. To select and set up the device parameters for variance, select the appropriate parameter from the available tabs. Resistors and capacitors distributions are set through their own buttons because Monte Carlo tolerance is built into the model and require its own setup. For other devices, use the Edit Distribution button to set up a particular parameter for Monte Carlo analysis. Clicking any one of these buttons will bring up the following dialog box:

The
name of the Part/Parameter that you are setting the distribution
for is displayed in the Parameter box. Use the Random Type
drop down box to set the Distribution Type. If
you specify Tolerance as a percentage, then it will be interpreted
as a percentage boundary on either side of the individual
parameter's given value. The main types of distributions are
Gaussian and Uniform. Gaussian distribution is the bell shaped
distribution, and Uniform gives any value in the range an
equal probability. To set individual parameter monte-carlo
distributions, edit the model properties of any part in the
circuit and if the model parameters are available, then you
should see an area where you can edit the range and distribution
type for the parameter.

Results of the Monte Carlo Test can be displayed in a 2D graph, 3D graph, or a Histogram, which displays the distribution frequency of the results. Each graph type is set up under the respective tab in the Monte Carlo setup area. When specifying the Histogram, the results will appear as a set of curves.

When
running a monte-carlo simulation, at each simulation iteration,
parameters are set to values that are different than their
specified values according to their tolerances.

When you have more than one parameter being offset by a tolerance,
sometimes you may want them to move together, and sometimes
you may want them to move distinctly.