# File Circuit Block

Use the File circuit block type to define either a measurement or simulation circuit that uses an S-parameter file to model the fixture, cable, probe, or device.

In the Setup dialog box's S-Parameter File Settings area, click Browse... to select the S-parameter file. The application accepts both Touchstone files (.s1p, .s2p, .s3p, .s4p, .s6p) and CITIfile (.cti) files.

To create S-parameter files of your device in the Touchstone format, you can use a vector network analyzer or circuit simulator.

To view magnitude, phase, or group delay plots of the S-parameter file, click Viewer... to open the S-Parameter/Transfer Function Viewer.

## Options for 2-Port S-Parameter Files

For a 2-port S-parameter file, the Flip Model option lets you flip the port numbering. Normally, port 1 is the input and port 2 is the output, but if Flip Model is selected, the model is flipped, port 2 becomes the input, and port 1 becomes the output.

## Options for 3-Port S-Parameter Files

For a 3-port S-parameter file, the Flip Model option lets you flip the model. The Port Numbering option lets you change the numbering when the model is flipped or not flipped. These two options give you all possible combinations. The resulting port numbering is displayed next to the selection.

## Options for 4-Port S-Parameter Files

For a 4-port S-parameter file, the Flip Model option lets you flip the model. The Port Numbering option lets you change the numbering when the model is flipped or not flipped. If these two options do not give you the port numbering you want, select Edit Port Order, use the port number drop-down selections to specify the numbering you want, and click Apply. To return to the default port numbering, click Undo.

The resulting port numbering is shown in the dialog box by the selections made.

## Options for 6-Port S-Parameter Files

For a 6-port S-parameter file, the Flip Model option lets you flip the model. The Port Numbering option lets you change the numbering when the model is flipped or not flipped. If these two options do not give you the port numbering you want, select Edit Port Order, use the port number drop-down selections to specify the numbering you want, and click Apply. To return to the default port numbering, click Undo.

The resulting port numbering is shown in the dialog box by the selections made.