Introducing the Smith Chart Utility

The Smith Chart Utility provides full Smith Chart capabilities, synthesis of matching networks, enabling impedance matching and plotting of constant Gain / Q / VSWR / Noise circles. The Smith Chart Utility is accessed from the Schematic window Tools or DesignGuide menus.

The Smith Chart Utility documentation includes these sections:

Step-by-Step Example

The step-by-step example takes you through the through the design and analysis of a single frequency impedance matching network. After completing this example, you should have a basic understanding of the Utility and be ready to begin using the tool. Follow these steps to begin:

Setting Up the Design Environment

Before you can use the Smith Chart Utility, you must set up the design environment by using these steps:

Setting DesignGuide Preferences

All DesignGuides can be accessed through either cascading menus or dialog boxes. You can configure your preferred method in the ADS Main window or from the Schematic window.

To configure access through menus or dialog boxes:

  1. From the Main or Schematic window, choose DesignGuide > Preferences .
  2. In the DesignGuide Menu Style group box, choose either Use a selection dialog box or Use cascade menus .
  3. Close and restart the program for your preference changes to take effect.
Note
On PC systems, Windows resource issues might limit the use of cascading menus. When multiple windows are open, your system could become destabilized. Therefore, the dialog box menu style might be best for these situations.

The ADS Main window DesignGuide menu contains these choices:

DesignGuide Developer Studio > Start DesignGuide Studio is only available on this menu if you have installed the DesignGuide Developer Studio to open the initial Developer Studio dialog box.

DesignGuide Developer Studio > Developer Studio Documentation is only available on this menu if you have installed the DesignGuide Developer Studio to open the DesignGuide Developer Studio documentation.

Note
Another way to access the DesignGuide Developer Studio documentation is by selecting Help > Topics and Index > DesignGuides > DesignGuide Developer Studio from any ADS program window.

Add DesignGuide opens a directory browser in which you can add a DesignGuide to your installation. This is primarily intended for use with DesignGuides that are custom-built through the Developer Studio.

List/Remove DesignGuide opens a list of your installed DesignGuides. Select any that you would like to uninstall and choose the Remove button.

Preferences opens a dialog box that enables you to:

Opening a Project

The ADS design environment is set up within a project.

To create a new project:

  1. From the ADS Main window, choose File > New Project or click Create a New Project on the toolbar.
  2. In the dialog, define the location of the project and assign a project name.

Opening a Schematic Window

A new schematic design is needed to contain the lowpass component for this example.

To open a Schematic window:

  1. From the ADS Main window, choose Window > __ New Schematic or click New Schematic Window on the toolbar. A new Schematic window appears.
    Note
    Depending on how your ADS preferences are set, a Schematic window can appear automatically when you create or open a project.
  2. In the Schematic window, choose File > New Design to create a design named SmithChartExample .

Opening the Smith Chart Utility

The Smith Chart Utility is accessed from the Tools menu or the DesignGuide menu in the Schematic window.

To open the Smith Chart Utility:

  1. In the Schematic window, choose Tools > Smith Chart . The Control window opens. Or, you can choose one of these paths from the DesignGuide menu:
    • DesignGuide > Amplifier > Tools > Smith Chart Utility
    • DesignGuide > Filter > Smith Chart
    • DesignGuide > Mixers > Tools > Smith Chart Utility
    • DesignGuide > Oscillator > Tools > Smith Chart
      Note: Expand the list under Tools by clicking the + sign.

Using the Control Window

All Utility features are available from the Control window. The Control window houses menus, a toolbar, and SmartComponent manipulation controls. The menus and toolbar buttons perform the basic functions of design, delete, and display the SmartComponent palette. The window can be placed anywhere on the screen. Explore the window menus as well to familiarize yourself with the basic Utility capabilities.

The pull down lists at the top of the utility window are designed to help you navigate multiple schematic windows and SmartComponents. You can use the Current Schematic drop-down list box to select any of the currently opened schematic windows. This field is updated any time Smith Chart Utility window is selected. You can use the SmartComponent drop-down list box to select any of the SmartComponents on the currently selected schematic window.

Using the Control Window
When you choose the DA_SmithChartMatch1 SmartComponent from the SmartComponent drop-down list box, the following dialog is displayed:

This dialog allows you to update the selected SmartComponent with the changes made using the Smith Chart utility, or conversely, update the Smith Chart Utility with the parameters of the SmartComponent. Selecting another component from the dropdown list will update the Smith Chart with the parameters of that component.

To close the Control window:

Designing and Analyzing a Network

Load and source matching networks for amplifiers can be designed easily using the Smith Chart. Using the Utility follows a normal design flow procedure:

Note
Before starting this section of the step-by-step example, confirm your setup (Setting Up the Design Environment).

Displaying the SmartComponent Palette

The program contains a SmartComponent palette, Smith Chart Matching Networks , that provides quick and easy access to the SmartComponents. A blue accent in the upper-left corner of a palette button indicates the component is a SmartComponent.

You can display the SmartComponent palettes in one of these ways:

Placing Example Component in the Design

To place a SmartComponent in the design:

  1. Click DA_SmithChartMatch on the component palette to select the component.
  2. Click within the schematic window to place the component.
    • You can change the orientation of the SmartComponent before placement by choosing from the Insert > Component > Component Orientation commands or by selecting Rotate by -90 repeatedly from the schematic toolbar.
    • The place component mode remains active until you choose End Command from the schematic toolbar.
Note
When a SmartComponent is placed initially, a temporary component is used to place and specify the parameters for the SmartComponent. This component does not contain a subnetwork design. After the utility has been used to design the SmartComponent, the temporary component is replaced with a permanent component. The SmartComponent is renamed to DA_ComponentName_DesignName and an autogenerated design is placed inside the SmartComponent's subnetwork design file. Subsequently, if the SmartComponent parameters are edited, the utility must be used again to update the subnetwork design file.

Designing the Amplifier Using the Smith Chart

During this example, you design the load matching network for this specific amplifier design problem:
Design a microwave transistor amplifier, operating at 3 GHz, to have an operating power gain of 9 dB. The transistor S-parameters are:

S11 = .641 - -171.3�
S12 = .057 - 16.3�
S21 = 2.058 - 28.5�
S22 = .572 - -95.7�

Changing SmartComponent Parameters

Parameters can be changed directly from the Control window.

To edit the DA_SmithChartMatch component parameters:

  1. In the Control window, select the DA_SmithChartMatch component from the SmartComponent drop-down list. This ensures all changes are referenced to this component.
  2. From the Smith Chart window menu, choose View > S-Parameters . In the dialog box, enter the S-parameters (magnitude and angle) for this amplifier and click Done.

Displaying the Operating Power Gain Circle

To display the Operating Power Gain circle and its corresponding control box:

Set Frequency

To set operating frequency:

  1. Return to the Smith Chart utility main window.
  2. In the Frequency/GHz field, enter 3 and click OK to continue.

Finding Source and Load Points

For this example, we use a 50 Ohm load. The source lies on the power gain circle. First, place the terminations onto their correct locations in the Smith Chart using the Smith Chart Drawing Palette.

To place the source and load on the chart:

  1. Place the source termination by clicking the drawing palette button Source Termination Conjugate and then moving the crosshairs until gamma on the status panel at the bottom of the Smith Chart shows approximately .36 - 47.5�.
  2. Highlight the source termination marker by clicking in the middle of the marker until a pink box highlights the marker. The load termination does not need to be moved since the load termination defaults to 50 Ohm.

Fixing Termination Accuracy

If the source termination is not exactly .36 - 47.5� the source termination can be changed by entering the correct values into the Gamma section of the status panel.

Drawing the Matching Network

To draw the matching network:

  1. Select the Shorted Stub component from the drawing palette and click the end point in the vicinity of Gamma .45 - 117�.
  2. Select the Line Length component from the drawing palette and select its end point to be near the source marker. Fine tuning can be done by dragging both green node markers until the end is exactly on the source marker.

Analyzing Frequency Response

To analyze the frequency response:

  1. Click the Reset button next to the Network Response plot to re-normalize the start and stop frequencies.
  2. For Type select Mag and for S-Parm select S11 . Notice that at 3 GHz the magnitude of S11 is zero, implying a good matching network.

Previewing Matching Network

After building, the network is displayed in the Network Schematic box.
To edit the network from the display:

Building the Circuit

To build a circuit into the Smith Chart SmartComponent:

Examining the Matching Component Design

You can look at the details of the autogenerated design inside the SmartComponent's subnetwork.
To examine the component's subnetwork:

  1. Select the component DA_SmithChartMatch .
  2. Click Push Into Hierarchy on the schematic toolbar to reveal the subnetwork.
  3. After examining the design, click Pop Out on the schematic toolbar to close the view.
    This completes the step-by-step example.
 

Privacy Statement  | Terms of Use  | Legal | Contact Us  | © Agilent 2000-2008 

Contents
Additional Resources