Overview of RF Tool Example
In this example, we model the gain and noise figure of a cascaded network and then analyze the network using RF Tool.
The network used in this example consists of an amplifier and two transmission lines. Here, we learn how to create and analyze the network using RF Tool.
Starting RF Tool
Type the following command at the MATLAB prompt to open the RF Tool window:
rftool
Creating the Amplifier Network
In this part of the example, you create a network to connect the amplifier components in cascade.
In the RF Component List pane, click Add.
The Create Network or Component dialog box opens.
In the Create Network or Component dialog box:
Select the Network option button.
In the Network Name field, enter Amplifier Network.
This name is used to identify the network in the RF Component List pane.
In the Network Type list, select Cascaded Network.
A Cascaded Network means that when you add components to the network, RF Tool connects them in cascade.
Click OK to add the cascaded network to the session.
The network now appears in the RF Component List pane.
Populating the Amplifier Network
This part of the example shows how to add the following components to the network:
Transmission Line 1
Amplifier
Transmission Line 2
Transmission Line 1
In the Component Parameters pane, click Insert to open the Insert Component or Network dialog box.
In the Insert Component or Network dialog box:
Select the Component option button.
In the Component Name field, enter Short Transmission Line.
This name is used to identify the component in the RF Component List pane.
In the Component Type pull-down list, select Transmission Line.
In the Value field across from the Line Length (m) parameter, enter 0.001.
Click OK to add the transmission line to the network.
Amplifier
In the Component Parameters pane, click Insert to open the Insert Component or Network dialog box.
In the Insert Component or Network dialog box:
Select the Component option button.
In the Component Name field, enter Amplifier.
This name is used to identify the component in the RF Component List pane.
In the Component Type list, select Data File.
In the Import from File dialog box that appears, click Cancel . You will specify the name of the file from which to import data in a later step.
In the Value field across from the Interpolation parameter, enter cubic.
This value tells RF Tool to use cubic interpolation to determine the behavior of the amplifier at frequency values that are not specified explicitly in the data file.
In the Value field across from the File Name parameter, enter default.amp.
Click OK to add the amplifier to the network.
Transmission Line 2
In the Component Parameters pane, click Insert to open the Insert Component or Network dialog box.
In the Insert Component or Network dialog box, perform the following actions:
Select the Component option button.
In the Component Name field, enter Long Transmission Line.
This name is used to identify the component in the RF Component List pane.
In the Component Type list, select Transmission Line.
In the Value field across from the Line Length (m) parameter, enter 0.025.
In the Value field across from the Phase Velocity (m/s) parameter, enter 2.0e8.
Click OK to add the transmission line to the network.
Simulating the Amplifier Network
In this part of the example, you specify the range of frequencies over which to analyze the amplifier network and then run the analysis.
In the Analysis pane, change the Frequency entry to [1.0e9:1e7:2.9e9].
This value specifies an analysis from 1 GHz to 2.9 GHz by 10 MHz.
In the Analysis pane, click Analyze to simulate the network at the specified frequencies.
RF Tool displays a Smith Chart, an XY plot, and a polar plot of the analyzed circuit.
You can modify the plots by
Selecting and deselecting the S-parameter check boxes at the bottom of each plot to customize the parameters that the plot displays.
Using the pull-downs at the top of each plot to customize the plot options.
Exporting the Network to the Workspace
RF Tool lets you export components and networks to the workspace as circuit objects so you can use the RF Toolbox functions to perform additional analysis. This part of the example shows how to export the amplifier network to the workspace.
In the RF Tool window, select File > Export to Workspace.
In the Variable name field, enter CascadedCkt.
This name is the exported object's handle.
Click OK.
RF Tool exports the amplifier network to an rfckt.cascade object, with the specified object handle, in the MATLAB workspace.
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