Importing and Exporting Layouts

The import/export translators in the Advanced Design System are highly configurable. Each translator has an associated options file that controls how the translator works. Default options files are included with the program and are automatically used unless you specify otherwise.

This section provides an overview of importing and exporting layouts. For details on available formats and descriptions of the options associated with each, refer to Available File Formats in the Importing and Exporting Designs documentation.

Importing a Layout

Use the following procedure to import a layout.

1. In the Layout window, choose the command File > Import. The Import dialog box appears.
2. From the Import dialog box, select the desired format.
3. Click Select File, choose a file name, and click OK.
4. Define any options or layer attributes.
5. Click OK. The file is translated into the program. One or more design files can be created.
   For all translators, one or more designs can be created. The top level design for IGES or GDSII is displayed in the Layout window (no schematics are created using any of the translators).
   

   Note Errors or warnings generated during translation are written to a write<translator>.log file, such as writegds.log (GDSII), writeigs.log (IGES), or writeegs.log (EGS).

Opening and Viewing a Translated Layout

Use either the design tree in the Main window, or the File menu in the Layout window to open an imported layout.

Saving a Translated Layout

You must explicitly save a translated design. It is not automatically saved. Use the following step to save one or more translated designs (individual designs created during the translation of a hierarchical design):
In the Main window, choose the command File > Save All Designs.

Listing the Hierarchy of a Translated Layout

In the Layout window, choose the command Tools > Hierarchy.

Exporting a Layout

This section provides information on exporting layouts. For details on available formats and descriptions of the options associated with each, refer to Available File Formats in the Importing and Exporting Designs documentation.

Preparing a Layout for Translation

Preparing a layout for translation consists of some or all of the following steps:

• Remove (flatten) any hierarchy that exists in the layout. This is necessary if you want to make changes that would affect all levels of the hierarchy, such as merging shapes.
• Edit the shapes that make up the graphical representations of the circuit components in the layout. The most common editing steps are to:
  • Merge graphics shapes that are on the same layer and touching (to eliminates boundaries between components so that the layout consist of graphics only).
  • Apply process offsets.
  • Create reverse images.
  • Change colors.

Layouts are sometimes edited to reverse the arrangement of colors: to replace white with black, for example.

• Change the visibility or arrangement of layers.

The steps you must use depend on the type of translation, and on what must appear in the finished file.

Flattening Instances to Eliminate Hierarchy and Connectivity

When you flatten components, you turn each component in the layout into a set of unrelated shapes. Component grouping is lost, and the shapes no longer behave as an electrical entity for simulation. Use the following steps:

1. In the Layout window, choose File > Generate Artwork.
2. When the program prompts you for a new design name, enter the desired name and click OK.

Hierarchy is removed so that all primitives are contained in the copied top-level layout icon.

Adding a Process Offset

It is sometimes necessary to have two layers that are almost the same except that one has a process offset. A process offset is a fixed amount of space (width) that is added to or subtracted from all dimensions of an object to compensate for production tolerances. Process offsets are used to create objects that overlap or underlie other objects, and to fix the actual amount of the overlap. If the object is a polyline or an arc, the object must have width to use a process offset. In addition, when process offsets are used with these primitives, only width is affected; process offsets do not change the endpoints of polylines or arcs. To create a process offset in your layout, copy the shapes from one layer to an empty layer, merge the shapes on the new layer, and then oversize (or undersize) the merged shapes.

Copying Shapes to a New Layer

To copy shapes from one layer to another:

1. If the layer to which you want to copy the shapes does not exist, choose Options > Layers to display the Layer Editor, then add the desired layer.
2. In the Layout window, select the shapes that you want to copy.
3. Choose Edit > Copy/Paste > Copy to Layer.
4. In the Copy to Layer dialog box, select the destination layer and click OK.

   Note The program places a copy of the selected shapes on the destination layer, in exactly the same place as they appear on the source layer. Because of this, you cannot see the copied shapes. When you click OK, a copy is placed on the destination layer; click Apply only if you want to select an additional layer to copy shapes to.

Merging Shapes

Merging replaces all shapes on the same layer and touching with combined shapes. This step is especially necessary before doing process offsets with negative values, but should follow the elimination of hierarchy, as described in Flattening Instances to Eliminate Hierarchy and Connectivity.

To merge shapes:

1. Select the shapes that you want to merge.
2. Choose Edit > Merge.

Resizing Shapes

You can increases or decreases the outline size of a shape, which is sometimes needed to compensate for a manufacturing process.

To resize shapes:

1. Select the shapes that you want to resize.
2. Choose Edit > Scale/Oversize > Oversize.
3. In the Oversize dialog box, enter (in layout units) how much you want added to or removed from the selected shapes. A positive number increases the size of a shape, a negative number decreases it.
4. Click OK.

Creating a Reverse Image of a Layer

You can create a ground plane or a solder mask that includes the area between shapes, as follows:

1. Copy the desired shapes to a an empty layer.
2. Place a rectangle (that represents the ground plane) over the shapes.
3. Choose Edit > Create Clearance.
4. When prompted, select the rectangle that represents the ground plane, then click OK.
5. In the Create Clearance dialog box that appears, enter any clearance you want for a ground plane (or offset you want added to the final shapes when creating a solder mask).
6. Select the shapes and click OK.
7. Select and delete the shapes to leave the ground plane/solder mask.
   

Translating a Layout

To export a layout:

1. In the Layout window, choose the command File > Export. The Export dialog box appears.
2. From the Export dialog box, select the desired format.
   Only one format can be specified at a time. The format you choose determines which options are available for translation. The options control the program translator.
3. If desired, specify a file name. If no file name is given, the name of the translated design is used. You do not need to specify the file extension.
4. Define any preferences or layer attributes (both in the Options menu).
   To specify the GDSII layer number or IGES level number to be used in exporting a design, choose Options > Layers to access the Layer Editor. Valid GDSII layer numbers are 0 through 255.
5. To start the translation process, click OK. If no path is specified, the file is written to the current project directory.