IFF Files

The Intermediate File Format (IFF) is an ASCII intermediate file. The file has a simple, line-oriented command structure with a fairly rich set of constructs, thus simplifying design transfer between Agilent Technologies products and third-party EDA tools. This format is machine- and application-independent.

The types of information that can be represented in the IFF format include:

• Design Objects
  • Symbols
  • Layouts
  • Schematics
• Connectivity
• Design Object Hierarchy
• Hierarchical and Design Object Properties

IFF files are used as the exchange mechanism when transferring designs between Advanced Design System and third-party EDA tools such as Mentor Graphics Design Architect and Cadence Analog Artist.

Importing IFF Files

The procedure for importing each format is generally the same, however the available options differ. For a step-by-step tutorial on importing a layout file, refer to Importing a Layout. For specific import options related to importing IFF Files, refer to Import IFF Options.

Import IFF Options

The Import IFF Options dialog box that appears is dependent upon where you execute the IFF import from. If the import is invoked from the ADS Main window, the following Import IFF More Options dialog box appears.

Remove IFF File After Import

When this option is selected, the .iff file is removed once the file is successfully imported. This option is not selected as the default.

Log verbose messages

When this option is selected, ALL translation information is recorded in the ifftolib.log file resulting in step-by-step description of what happened internally during your translation. This option is primarily intended to be used as a diagnostics tool so the default mode for this option is deselected. Note that error and warning messages will always appear in your status window regardless of this selection.

Synchronize ports to symbol using node name

When this option is selected, the IFF import resets the symbol pin numbers to match port numbers based on the node name of the schematic port. By default, symbol pin numbers are matched to schematic port numbers based on the port's instance name.

Use port name for connected wire label

For each wire attached to a port, the wire label will be set to name of the port from the Cadence environment. To maintain proper connectivity in the ADS environment, this option must be enabled if connectors share a common name in the Cadence environment.

Use layouts from libraries instead of building local copies from IFF file

When this option is selected, library elements that already exist in the system libraries are not recreated for the imported file. Instead, these elements are read from the local libraries; if an element does not exist in a local library, then it is newly created. This option is deselected as the default, and all elements are created/recreated in the local project.

Default Library Name For Library Parts

When the IFF file does not specify a library name for a component that needs to be created, the library name specified in this field is used. This is necessary for environments that do not support the concept of a library.

Note The Default Library Name For Library Parts field is identical to the field of the same name in the Export IFF Options dialog box. Changes made to this field will modify the contents of the field in the Export IFF Options dialog box.

About Component Libraries

A component library in ADS consists of a collection of component definitions. Each primitive component has an associated component name, symbol and predefined component parameters that include relevant physical and electrical characteristics.

The IFF translator can be used as the initial step in creating an ADS component library however, this topic is outside of the scope of this manual. Creating an ADS component library using IFF requires specialized tools and training. If you're interested in learning more about this topic, contact Agilent EEsof-EDA's Solution Services.

Trace Handling

Trace Handling enables you to select how you want your meander elements interpreted during a translation.

Trace When this option is selected, meander elements are translated as simulatable traces with pins. This is the default setting.
Path When this option is selected, meander elements are translated as primitive data type with center line and width. The default for this option is deselected.
Polygon When this option is selected, meander elements are translated as polygons. The default for this option is deselected.

Note If you choose Use layouts from libraries instead of building local copies from IFF file in the Import IFF Options dialog box, choose Path in the Trace Handling options. Fixed artwork is not simulatable, therefore it is not necessary for the interconnects to be simulatable.

Importing from a Schematic Window

If the import is invoked from the ADS Schematic window, the following Import IFF More Options dialog box appears.

Note that the same options are used with the exception of the Use layouts from libraries instead of building local copies from IFF file check box and the Trace Handling options. For information on these options, refer to Import IFF Options.

Exporting IFF Files

To export an IFF file:

1. Follow the steps as outlined in Exporting a Layout. For available options (accessed via More Options in the Export dialog box), see Export IFF Options.
2. When the translation is complete, an Information Message window appears. Click OK to dismiss this window.
3. The IFF Export log appears:
   
   Review the log, searching for any warnings or error messages generated during export.
   The log file appears in the hpeesofeedit window by default. This window is provided as a means of viewing the file and is not intended for editing.
4. To dismiss the log window, choose File > Quit.

Export IFF Options

Destination IFF File name

Use the Destination IFF File name field to enter the full path of the destination file. Alternatively, you can click Browse to open the Export File Selection dialog box and locate the destination path. After selecting the destination path and entering the file name, click OK to accept the selection and return to the Export IFF Options dialog box. The appropriate suffix is appended to the filename automatically.

IFF File Overwrite Options

Overwrite IFF File When writing to an existing file, the contents of that file are overwritten.
Append to IFF File When writing to an existing file, the new data is appended to the existing file. This is the default setting.

Output disabled instances to the IFF file

When this option is selected, if an instance is disabled in the schematic, it will still be output into the IFF file. If the checkbox is deselected (default), disabled instances will not be exported. This option can be utilized to omit certain components from being transferred to remote environments that might not support the components (e.g. disable the simulation components prior to creating an IFF file to send to Cadence, which does not have any definitions for the simulator components). Activate this option if you want to get everything. Deactivate this option if you want to filter out the unused/unwanted components.

Output ADS Item Definition properties

When this option is selected, ADS Item Definition properties are utilized to recreate the information necessary to simulate a component for ADS. For example, if you have parameters on a resistor, some Item Definition properties are created in the IFF file (e.g. R_ADS_UNIT=1), which allow the IFF importer to exactly recreate the component as it exists in ADS. However, other tools will not recognize the Item Definition parameters, and may misinterpret the properties as being separate. If library symbols are being exported to other environments that do not recognize the ADS Item Definition parameters, the option should be turned off. This option is deselected by default.

Put a space between numbers and the scalar/unit

When this option is selected, parameter values are exported as they normally appear in ADS (i.e. with a space between the number and the scalar, e.g. "1 pF"). If the checkbox is deactivated, the exporter converts the values into the IFF value specification, which is to have no space between a number and a scalar (e.g. "1pF"). Ideally, an IFF exporter should interpret either form of number, and set the value internally to whatever is normal for that environment. Some environments (e.g. Mentor Graphics) do not interpret the IFF property values in any way. For Mentor IC, this means the numbers need to have no space in them, because, when they are used within SPICE simulations, the space will cause syntax errors in the simulator. However, for Mentor Board, they require the ADS components to have a space in them, because the RF Architect ADS library is set up to expect values to have a space between a number and a scalar/unit.

If you are exporting designs to Mentor Boardstation, you must select this option for IFF imports to work into their environment. An additional issue can come up if you create variables, and then assign scalar values to the variable (e.g. "R1 kOhms"). When this is exported, if the option is not set, it would convert to "R1koh", which could no longer be interpreted correctly. Note that this second option is considered bad practice (the scalar should be included in the variable value for R1, and no units should be specified); however, ADS does allow you to format variables in this way. If you are using variables in this way, you must set this option to true. This option is deselected by default.

Output annotation position for schematic components

This option stores information about the position of the component text annotation in the schematic window. Annotation text includes the component type, name and parameters as displayed next to the component. Enabling this option may be useful if the annotation has been moved in ADS, though even with this option enabled some environments may not preserve the position of the annotation.

Default Library Name For Library Parts

When the IFF file does not specify a library name for a component that needs to be created, the library name specified in this field is used. This is necessary for environments that do not support the concept of a library.

Note The Default Library Name For Library Parts field is identical to the field of the same name in the Import IFF Options dialog box. Changes made to this field will modify the contents of the field in the Import IFF Options dialog box.

About Component Libraries

A component library in ADS consists of a collection of component definitions. Each primitive component has an associated component name, symbol and predefined component parameters that include relevant physical and electrical characteristics.

The IFF translator can be used as the initial step in creating an ADS component library however, this topic is outside of the scope of this manual. Creating an ADS component library using IFF requires specialized tools and training. If you're interested in learning more about this topic, contact Agilent EEsof-EDA's Solution Services.

Schematic Hierarchy Option

The Schematic Hierarchy Option drop-down list enables you to establish how much of the schematic hierarchy is exported:

Current Design Only Write current level only. Complete design information for the current design is exported. Instance-specific information (parameter values and coordinates identifying position) is also exported. Detailed definitions of a referenced design are not exported.
Current Design, Selected Projects and No Library Parts Complete design information for the current design is exported. Referenced designs that reside in a project selected for inclusion during export and are part of the current design's hierarchy are also exported. Library parts are not exported. This is the default setting.
Current Design, Selected Projects and All Library Parts Complete design information for the current design is exported. Referenced designs that reside in a project selected for inclusion during export and are part of the current design's hierarchy are also exported. In addition, library parts are exported.

Project Hierarchy

Displays the current project. If hierarchical, all included projects are listed in the appropriate order.

Projects Included During Schematic Export

The projects for which schematic design information is exported. You may customize this list if the current project is hierarchical. (Note that complete layout hierarchy is always exported.)
To add a project to this list:

1. In the Project Hierarchy list, click the desired project.
2. Click the Include button. The project is added to the Projects Included list.

To include all projects, click Include All.

To remove a project from the Projects Included list:

1. In the Projects Included list, click the entry you want to remove.
2. Click the Remove button. The project is removed from the list.

To remove all entries from the Projects Included list, click Remove All.