Parametric analysis performs several consecutive simulations, varying the value of some parameters at each step. You can set up to six parameters each of which can be included or excluded from the simulation by setting the Use this parameter option. For example, if you use two parameters then the value of the parameter with the lowest index is varied throughout its range for each of the values assumed by the parameter with the highest index.

Note:
To perform a Parametric analysis, select Parametric Analysis in the Analysis Mode box in the Setup dialog box for one of the following analyses: AC, Operating Point, Transient, Transfer Function, Noise, Distortion.

Tip:
A Parametric analysis can produce a large amount of data causing an excessive use of memory and a lower speed of simulation. To reduce the amount of data that is stored during a simulation it may be convenient to specify the names of only the vectors of interest, in this case only the data related to the specified vectors will be stored.

Variable

In this group you must select the parameter to be changed during the simulation.

Type

Select the type of parameter to vary: a component parameter, a model parameter, the value of a simulator option, the value of a global parameter or the analysis temperature.

Name

Select the name of the component, model, option or global parameter.

Parameter

Select which component or model parameter, indicated in the Name box, should be changed.

Change values

Specify the range of values and how they should vary. Values may vary in the following ways:

Linear sweep. The variable assumes the values between Initial Value and Final Value in steps specified by the Increment value.
Sweep by decades. The variable is swept logarithmically by decades between the Initial Value and Final Value. For each interval, the number of values specified by Number of points is taken. The extremes of the intervals are such that extreme2=10*extreme1. For example, if you specify 1K for the initial value, 1Meg for the final value and 10 for number of points. The analysis interval is divided into three sub-intervals and the values are taken, on a logarithmic scale, as ten for each interval.
Sweep by octaves. The variable is swept logarithmically by octaves between Initial Value and Final Value. For each interval, the number of values specified by Number of points is taken. The extremes of the intervals are such that extreme2=2*extreme1. For example, if you specify 1K for the initial value, 1Meg for the final value and 4 for number of points. The analysis interval is divided into ten sub-intervals and the values are taken, on a logarithmic scale, as four for each interval.
Use a list of values. The variable assumes the values specified in the List of values box. The values must be separated by at least one space character.
List of string values. The variable assumes the values specified in the List of values box. The values must be separated by at least one space character. The use of string parameters is useful to vary the model associated with a component or when the value must be in function of a global parameter.

Use this parameter

You can set up to six parameters each of which can be included or excluded from the simulation by setting the Use this parameter option.

Analysis results

The result of a parametric analysis is a set of curves, each of which corresponds to a certain combination of the set parameters. The vectors returned by a parametric analysis are two-dimensional matrices in which each row is formed by the vector resulting from the simulation corresponding to a given combination of the set parameters. For example, the result of a parametric analysis in which the values of the two resistances R1 and R2 are varied so that R1 assumes the values 1K and 2K and R2 assumes the values 10K and 20K, will be a matrix of four rows in which, assuming that R1 corresponds to parameter 1 and R2 corresponds to parameter 2, the rows of the matrix are arranged as shown below:

Row 0 corresponds to the values: R1=1K and R2=10K.
Row 1 corresponds to the values: R1=2K and R2=10K.
Row 2 corresponds to the values: R1=1K and R2=20K.
Row 3 corresponds to the values: R1=2K and R2=20K.

For example, if the points analyzed are 50, the vector of the results for the voltage at the node NET1 is of the following type: NET1[4,50]. The vector has 200 elements in total arranged in 4 rows of 50 elements each. You can display the entire set of curves in a diagram by simply adding the NET1 vector to the diagram. To display the curves corresponding to the individual simulation steps, you must create the corresponding vectors as shown in the following examples.

To display	Do this
The entire set of curves	Click on the Plot button and add the vector NET1 to the list of vectors to be included in the diagram.
The curve corresponding to the first step of simulation (R1=1K and R2=10K)	Click the Vectors button and in the dialog box add a new vector of name NET1_R0 and with the value equal to NET1[0]. Click on the Plot button and add the vector NET1_R0 to the list of vectors to be included in the diagram.
The curve corresponding to the last simulation step (R1=2K and R2=20K)	Click the Vectors button and in the dialog box add a new vector of name NET1_R3 and with the value equal to NET1[3]. Click on the Plot button and add the vector NET1_R3 to the list of vectors to be included in the diagram.
The curves corresponding to rows 1 and 2 of the results matrix	Click the Vectors button and in the dialog box add a new vector of name NET1_R1R2 and with the value equal to NET1[1,2]. Click on the Plot button and add the vector NET1_R1R2 to the list of vectors to be included in the diagram.