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13.14. Stability Analysis Wizard

The Stability Analysis Wizard guides you through the steps needed to analyze the stability of a selected circuit using the STAN stability analysis. The STAN approach enables nonlinear stability analysis so you can study the circuit stability, for example, as a function of swept power. Each sweep point performs an HB analysis which is followed by a set of small signal analysis over the chosen frequency band. The data gathered from each stability probe is sent to STAN, which returns the identified poles and zeros shown in Microwave Office graphs. You need at least one schematic with a minimum of one port and one NCONN or STAB_PROBE element to run the Stability Analysis Wizard. NCONN elements are searched only from the top level schematic. If the wizard finds STAB_PROBE elements in some of the subschematics, stability measurements are created for them. A copy is made only from the top level schematic. IVCAD must be installed on the localhost or on a remote server.

To access the Stability Analysis Wizard:

  1. Open the Wizards node in the Project Browser and double-click Stability Analysis using STAN. The main Stability Analysis dialog box displays.

  2. Select the circuit schematic you want to analyze, then click Next. To analyze the data, you need IVCAD with STAN and scripting plugins. The Stability Analysis/Simulation Settings dialog displays. For Stability Analysis option details, see “Stability Analysis Wizard Simulation Settings Dialog Box”.

  3. Click Finish to run the STAN analysis. The wizard generates a copy of the original schematic and adds an NLSTABILITY block with specified STAN options and small signal test conditions (or updates parameters if they exist) and replaces the selected port with a swept source port if needed, and then connects new probes to selected NCONNS.

  4. The wizard runs a simulation, and the IVCAD server analyzes STAN data. The result is a graph with poles and zeros for each STAB_PROBE element (SchematicName_STAN_RESULTS_ProbeName).

13.14.1. IVCAD Server Installation and Configuration

The Stability Analysis Wizard and the APLAC simulator search your local IVCAD installation path from the Registry. Only one IVCAD can be installed at a time. The IVCAD installation directory is written to the Registry and it remains unchanged when IVCAD is updated.

  • On a 32-bit system: HKEY_LOCAL_MACHINE\SOFTWARE\Maury Microwave\IVCAD

  • On a 64-bit system: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Maury Microwave\IVCAD

The installation directory is the value of the "InstallDir" property.

Your script server must be configured with the following settings before using it from the NI AWR Design Environment software:

  • Port number (ensure that the port is not blocked by a firewall)

  • The output termination character must be set to Linux \n after each response, or Windows \r\n after each response. The wizard and the server must use the same output termination character.

  • Charset ISO-8859-1

  • The option to automatically start the server with the application must be selected.

You can change local IVCAD server settings only on the IVCAD scripting server. To use the new settings you must restart the server, which saves them to \Documents\IVCAD\settings\settings.xml when IVCAD closes. If a local IVCAD installation is not found, the remote server is used. The APLAC simulator reads these settings from the XML file(s) before STAN analysis. If a remote server settings file (StabilityAnalysisWiz_settings.xml) is not found, only the local IVCAD settings file is used and defaults are used for the missing settings (timeout).

This wizard saves IVCAD remote server settings to the StabilityAnalysisWiz_settings.xml file in the IVCAD settings folder. You should run the wizard at least once to create the file and save the correct settings before STAN analysis can be run on the remote IVCAD server. All IVCAD settings are saved only to the XML file, not to the Microwave Office project file (.emp). Changing the settings affects all STAN analyses. The Stability Analysis Wizard writes IVCAD settings to the XML file when you click Finish. All other wizard settings such as STAN options, Small signal test conditions, and drive conditions are saved with each project.

When using an IVCAD remote server, all settings such as port number, output termination character, and charset must be correctly set in the wizard, and you must start the scripting server in IVCAD before performing STAN analysis. If using a remote server, the data is first copied to server's disk and after analysis the result file is copied back to the local disk.

When starting the IVCAD server manually (independent of awr_as.exe), you need to set the maximum memory used by IVCAD with a -m command line option. For example, ivcad.exe -m 1000 (where 1000 is max memory in MB, here 1 GB). In the current IVCAD beta, the limit is 1536 MB with a default of 495 MB.

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