How to Use Circuit Parameters

[asloane]

Hello Circuit Designers,

Circuit parameters are a powerful feature introduced in Multisim 13.0 that allows you to have increased flexibility when simulating a circuit. Basically, circuit parameters are user-defined variables that you use to assign a custom value to a component value.

Getting Started with Circuit Parameters:

Using the RLC circuit from the examples included with Multisim (attached to this post), we see that the values of each of the RLC components in the three stages are R=0.5 ohm, L=100nH and C=1nF as defined by the circuit parameters.

To set a circuit parameter, choose View->Circuit Parameters from the menu. The circuit parameters spreadsheet opens at the bottom of the workspace. From here you can add or edit all circuit parameters. To use a circuit parameter in your design, simply enter the parameter in the value field of a component. As shown below the selected resistor has a value that is twice the value set for R. You can find a good introduction to circuit parameters here.

Circuit parameters provide a powerful option when simulating designs by allowing you to quickly change a number of component values all at once or deduce component values based on design performance specifications. For more complex simulation scenarios you can create case structures to automatically obtain results from multiple simulation runs. Circuit parameters can also be used with sources such as a Pulse Voltage source, for example, by setting a Rise Time = .001 * period, a Pulse width = .5 * period and then iterate over multiple values of the period.

Here is a more advanced design that demonstrates a powerful way of evaluating different design cases and tuning multiple parameters of the circuit at the same time. The goal is to figure what component values will help meeting the design specifications.

Please let me know if you have any feedback or questions on this or any other Multisim topics.

Campbell B

National Instruments