Before Using the IFF Translators with Cadence

Before using the IFF translators, there are several topics that must be addressed. This chapter is broken down into three main sections that cover these issues:

• Configuring your Software for IFF Translation

• Understanding Component Library Requirements

• Constructing Schematics for IFF Translation

After covering the information in this chapter, you'll be ready to begin sharing your schematic files between ADS and DFII using the IFF translators.

Configuring your Software for IFF Translation

This section describes the details related to software requirements and configuring the ADS and Cadence design environments to support IFF translation. Before attempting an IFF translation, the appropriate licenses must also be installed and the Cadence environment must be configured to operate with the IFF translator.

Software Requirements

The IFF Translator described in this manual requires ADS 1.5 or later. IFF is supported by Cadence DFII versions 4.4.2*, 4.4.3QSR1, 4.4.5 and 4.4.6. IFF is also supported on all UNIX operating system versions from vendors which run this Cadence software. Refer to the following table for a summary of supported platforms. For additional information, please contact Cadence Design Systems, Inc.

Supported Platforms

Cadence DFII Version	AIX4	HPUX10	HPUX11	SUN55	SUN56	SUN57
4.4.2*	yes	yes	no	yes	yes	no
4.4.3QSR1	yes	yes	yes	yes	yes	yes
4.4.5	yes	no	yes	yes	yes	yes
4.4.6	yes	no	yes	yes	yes	yes

* Sub-version 100.1 or later.

License Requirements

In addition to the mainstream Cadence (DFII, Composer Schematic, etc.) and Advanced Design System licenses, the following additional product licenses are required.

Agilent Technologies Licenses

• trans_ads_schematic

  Note Before continuing, ensure that you have a valid license for the ADS schematic environment. For more information on ADS Licenses, refer to " Setting up Licenses on UNIX Systems " in the UNIX and Linux Installation manual.

Cadence Design Systems Licenses

• Virtuoso Schematic Composer (34500)

  Note This and all other Cadence licenses must be purchased from Cadence Design Systems, Inc.

Modifying the Cadence Initialization File

This section describes the information that must be added to the Cadence initialization file ( .cdsinit ) in order to configure DFII to run the IFF translator. Normally, only one .cdsinit file is read by DFII. DFII searches for the first .cdsinit file in the following order:

$CDS_INST_DIR /tools/dfII/local/.cdsinit	(global Cadence startup directory)
./.cdsinit	(local directory)
$HOME /.cdsinit	(home directory)

Add the following lines to your Cadence initialization file ( .cdsinit ):
{{load(strcat(getShellEnvVar("HPEESOF_DIR")
"/links/tools/iff/cadence/composer/mdsinit.il"))}}
Adding the above information to your .cdsinit file loads the SKILL code that sets up the IFF pull-down menu on the Cadence CIW as well as other code necessary for performing IFF transfers between DFII and Advanced Design System.

Note SKILL is Cadence's C/lisp-like interpretive programming language for framework and database integration.

Restarting Your Cadence Session

If you have already started your Cadence session and do not wish to interrupt it, source your .cdsinit file before attempting to use the IFF translator. For more information on Cadence initialization files ( .cdsinit) , refer to your Cadence documentation under " Setting Cadence Environment Variables ". If you're using version 4.4.5 or 4.4.6, you will need to restart your Cadence session to initiate the change.

Setting up the System `.cdsenv' File

A specific .cdsenv file must be created in the Cadence installation to support the operation of the IFF translator. To perform this operation, a script is provided that copies the default .cdsenv file from the ADS installation to the Cadence installation.
To install the .cdsenv file:

1. Change to the $HPEESOF_DIR/links/tools/iff/cadence/composer directory.
2. Locate the script called setupCdsEnv . This script copies the default .cdsenv file into the Cadence root currently set in your path. The Cadence root is determined by using the cds_root command.

   Note The cds_root command is located in the tools/bin directory of the Cadence directory hierarchy. You must have the tools/bin directory in your path for the setupCdsEnv script to function properly.

3. Run the setupCdsEnv script. The . cdsenv file is copied to:
   <cds_root> /tools/dfII/etc/tools/iff/.cdsenv
   If the iff directory does not exist, it will be automatically created.

   Note If you do not have this environment file installed, you will get messages similar to the following: {{*WARNING* Cannot find /apps/cadence/4.4.3/tools.hppa/dfII/etc/tools/iff directory to load environment variables *WARNING* envGetVal: could not find tool[.partition] `iff'}}

About the Local `.cdsenv' File

There is also a local .cdsenv file that is created and updated every time you click Apply or OK in the IFF Import and Export dialog boxes. This file contains the settings of the various fields and check boxes and it can be found in the directory where you started the Cadence application. For example, if you change the scaling factor (see Scaling Factor for Cadence to Target System) from 200 to 250 and then click Apply , the setting is saved and will appear the next time you open either the IFF Import or Export dialog box. These settings can become system defaults by manually editing the system .cdsenv file, located in the <cds_root> /tools/dfII/etc/tools/iff directory, setting each of the variables in the .cdsenv file to the desired setting.

Verifying your Cadence IFF Configuration

After meeting your license requirements and modifying the Cadence initialization file, you can run Cadence DFII to ensure that your configuration was successful. To launch DFII and verify your setup:

1. In a terminal window, change to the appropriate directory.
2. Run DFII by typing the appropriate command (typically icms or icfb ). The Cadence Command Interpreter Window (CIW) appears.
   

Cadence CIW Window

1. Check that the IFF menu item is displayed in the CIW menu bar as shown in Cadence_CIW_Window._For_detailed_information_on_the_available_command_options,_refer_to_Importing IFF Schematic Files into DFII and Exporting IFF Schematic Files from DFII.

Note Non-standard or customized start-up scripts for Cadence Design Framework II may not be supported. If you have difficulties, contact your system administrator.

Checking for the "basic" and "analogLib" Libraries

The basic library must be installed in Cadence DFII before attempting an IFF translation. If the basic library is not installed in the Cadence cdslib directory, there are potential transfer issues related to pin mapping. Fundamentally, DFII will not be able to generate pins when translating an IFF schematic from ADS without having the basic library available in Cadence.

If the analogLib library is not installed in the Cadence cdslib directory, there are potential transfer issues related to ground symbols and connector components. If you've developed your own ground symbol and placed it in an existing library, ensure that you activate the Export standard connectors as components option when exporting an IFF schematic file from DFII to ADS. The Export standard connectors as components option can be found in the Framework Output Transfer Form . For more information on this option, refer to Accessing the Framework Output Transfer Form. Also ensure that you use your own connector components in ADS, as opposed to the standard ADS connectors (i.e. Port and Ground ), to avoid any potential problems.

To ensure that the basic and analogLib libraries are available from the Cadence CIW:

1. Choose File > Open . The Open File dialog box appears.
   
2. In the Open File dialog box, click the Library Name pull-down menu item. If the basic and analogLib libraries are installed, they should both be available in this menu.
3. If the basic and/or analogLib libraries are not installed, work with your system administrator to obtain a copy of the missing library or libraries.
   Copy the basic library to:
   <Cadence_install_dir> /tools/dfII/etc/cdslib/basic
   Copy the analogLib library to:
   <Cadence_install_dir> /tools/dfII/etc/cdslib/analogLib
4. Repeat steps 1 and 2 to verify that the libraries are now available from the Open File dialog box.

Understanding Component Library Requirements

The fundamental library requirement for a successful IFF transfer is that both the Advanced Design System and Cadence Design Framework II contain compatible component libraries. This section provides an overview of compatible libraries and discusses the issues related to simulating your design.
Compatible libraries between two design frameworks can be considered equivalent component libraries for all practical purposes. While two EDA frameworks may have some differences in the way component information is handled, the fundamental component parameters for each primitive component must map each other to have the same function in one framework as it does in the other. Components and parameters such as component names, symbols, size and shape, symbol pin locations, etc. in the source framework must all map to corresponding components and parameters in the target framework. The diagram below displays an example of two equivalent, or compatible component libraries within two separate EDA frameworks.

Compatible Component Libraries

Simulating a Design Transferred via IFF

A circuit can be transferred from a source environment into a target environment via IFF translator and be simulated in the target environment only if the component libraries that have been used to create the circuit are compatible between the two environments.

Getting Help

Due to the detailed nature of creating compatible component libraries, it is recommended that you consult Agilent EEsof-EDA Solution Services for more information. Solution Services can provide training on how to configure compatible component libraries as well as complete library development solutions. Contact your local Agilent Technologies sales representative for more information on working with Solution Services.

Constructing Schematics for IFF Translation

The IFF schematic translator module enables bi-directional, fully hierarchical schematic transfer between the ADS and Cadence DFII Frameworks. You can edit your schematic in either environment, and when you transfer edited material to the other environment, all edits are preserved, including property changes.

Before attempting to transfer a schematic via IFF, ensure that all component libraries are compatible in all frameworks. This step is essential for a successful IFF transfer. For more information on compatible libraries, refer to Understanding Component Library Requirements.

To have a successful IFF transfer, it is required that only components that are contained within the compatible libraries be used in your designs. A hierarchical design approach is recommended for the implementation of RFIC schematic designs in ADS.

Implementing Power Supply Connections

Power supply connections ( power rails ) should be implemented through port construction in the subcircuits or through global named connections.

Separating Simulation Control Elements

Simulation control elements are not transferred between ADS and DFII. Because of the different way the two environments handle simulation setup, it is recommended that your simulation control elements in Advanced Design System be separated from your circuit schematic information using a hierarchical approach (i.e. top level contains simulation control and instance(s) of subcircuits containing DUT). This enables you to transfer only the schematic information in the subcircuit and will require you to set up simulation controls independently in the Cadence environment. For more information, refer to " Creating Hierarchical Designs " in the Schematic Capture and Layout manual.

Including Design Variables and Equations

If the design being transferred from ADS to DFII contains design variables or equations, the same variable should be manually set to the appropriate value or equation in the Cadence environment.

Note Advanced Design System equations are transferred in the IFF file; however, they are not translated to a Cadence equivalent.

Known Issues and Limitations

There are several known issues or limitations that you should become familiar with before attempting to perform an IFF translation.

• Only one schematic is allowed per cell in Advanced Design System.
• Extracted views are not supported by the IFF translator.
• Parameterized subnetworks require special setup not is not covered in this manual. It is recommended that parameterized subnetworks not be used if IFF is used to transfer designs between ADS and Cadence.
  For information, see the Netlist Translator for SPICE and Spectre manual.
• Inherited Connections are not supported in IFF transfers in ADS version 1.5 SP1A or earlier.
• Inherited Connections are supported in ADS via Power Pins. It is necessary to manually place Power Pins on symbols in ADS. IFF library transfers will not set up pins that utilize the ADS version of Inherited Connections.
  If IFF is used to transfer designs between ADS and Cadence, it is recommended that symbols use explicitly defined pins rather than Inherited Connections.
• ADS ports to have unique names. If multiple ports with the same name are used within a Cadence schematic, the IFF exporter will keep the first port with the name. All subsequent ports with the common name will be converted to wire labels.
• Area pins are not supported in ADS. It is important to have wires in your Cadence design connect to the center point of a symbol pin.
• Design variable in Cadence are not transferred to ADS via IFF. It is necessary to manually create a VAR component in ADS that will contain the CAdence design variables. Additionally, VAR components in ADS are not transferred to CAdence design variables. If VAR components are set up in ADS, you must manually create design variables in Cadence.
• In Cadence, text can be set at rotation angles of 0, 90, 180, and 270 degrees, but will only be rendered on screen at 0 and 90 degrees. In ADS, all four rotation angles will be rendered as set. To prevent differences in the way text is rendered between ADS and Cadence, only use angles of 0 and 90 degrees for text and avoid mirroring.