Derive Transfer Functions

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In this step of the Quick Start tutorial we will use this example circuit to derive a few Transfer Functions.

The previous page of this quick start tutorial explains how to enter this circuit into the circuit editor, Alternatively you can load the file QuickStart1.crc from the Tutorials\QuickStart directory. This file is a circuit document that contains the circuit as shown above.

Deriving a Transfer Function

We will derive a Transfer Function from the example circuit that expresses the relationship between Vout and Vin.

Select Transfer Function from the Components Toolbar.
To insert a new Transfer Function into the circuit document, click the left mouse button, drag until you see a rectangle, and then release. The Transfer Function dialog box will appear and allow the parameters to be edited.
Enter the label "T1" for this Transfer Function in the edit field in the upper left corner of the dialog box.
The list of Output Labels contains one item "Vout" which represents the Voltage tag that is stretched across the Inductor in the example circuit. Click once on the "Vout" item, to select it, in the Output Labels list and then click the insert button to paste the "Vout" label into the Output Equation.
The Input Source selection list only has one item "Vin" which represents the one Voltage Source in the example circuit. This is the Voltage Source we want to use in the Transfer Function we are going to derive.
The dialog box should look like this:

Now click the OK button.
CircSolver will compile the circuit and derive the transfer function "T1" which will then appear in the circuit document like this:

Change the circuit and derive another Transfer Function

We will now change a component value in the circuit and derive another Transfer Function.

With the left mouse button, double click the center of the 1 ╡F Capacitor to edit its parameters. Change the Capacitor's value to 2 ╡F and click the OK button.
Insert a new Transfer Function named "T2" into the circuit document, using the procedure described above, with the Output Equation set to "Vout" and the Input Source "Vin". Click the dialog box's OK button, the circuit is recompiled (because it was changed), and the following Transfer Function appears in the circuit document:
Change the Capacitor's value to 4 ╡F.
Insert a new Transfer Function named "T3" into the circuit document with the Output Equation set to "Vout" and the Input Source "Vin". The following Transfer Function appears in the circuit document:

We will use these Transfer Functions in the following pages of this Quick Start Tutorial to make Bode Plots and Time Domain Output Signals.

If you have trouble completing the steps in this page of the Quick Start Tutorial, you can load the file QuickStart2.crc from the Tutorials\QuickStart directory. This file is a circuit document that contains the circuit shown above and the three Transfer Functions T1, T2, and T3 already derived.