In the design of integrated circuits, the most popular format for interchange is the Calma GDS II stream format (GDS II is a trademark of Calma Company, a wholly . Portions of the GDSII Stream Format Manual, Documentation No. B97E, Feb. , reprinted with permission of Cadence Design Systems, Inc., River. GDS II is a database file format which is the de facto industry standard for . The GDSII or Stream file format stores its information in records.

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Retrieved from ” https: A zero value is represented by a number with all bits zero. For a step-by-step tutorial on exporting files, see Exporting a Layout. Plex numbers are not commonly used.

CHAPTER 1 GDSII format

After activating this option with the SetupDialog or via a macro, all box elements will be saved as a polygon. The least significant bit of the most significant byte is the plexhead flag. The first most significant bit of the first byte is the sign, one means negative, 0 means positive. GDSII interpreters will either impose such a limit explicitly, or will impose an implicit limit by running out of memory during recursive operations.

Starts with name of the first library and is followed by the second. The database is binary for compactness.

Contains the list of layers and data types included in the data file usually as specified by the user when generating the Stream file. However, it will not interference with any other GDSII tool as long as no cell with the mentioned named is used in gddii design. The latter can be viewed and manipulated with VTK compatible viewers, e.

strema The GDSII file format can contain multiple top-level instances that may or may not be related to one another. The minimum record length is four bytes. By activating this option via the setup dialog or via a macro, all saved GDS II files will be padded to this length by adding a 0 at the end of the file.

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The name of that instance is formaat in the Layout title bar. GDSII is an integer database. Applies to pathtype 4. In stream files created by non-Calma programs, this should be missing or all field should be 0. When this is selected, holes are converted to polygons. The elements within the braces can occur zero or more times. PATH [] No data is present. An x appears in the box to the left of selected attributes.

It is stored in twos complement format, with the most significant byte first. Two 2 byte integers. MAG [1B05] Eight-byte real: Cells may contain geometrical objects such as polygons boundariespaths, and other cells. There may be from 1 to 32 ACL entries, each consisting of a group number, a user number, and access rights. Improvements and Enhancements since ? Therefore, sfream consideration should be given to the use of curved elements and the extensive use of arcs and circles in your layout design.

Objects contained in a GDSII file are grouped by assigning numeric attributes to them including a “layer number”, “datatype” or “texttype”. GDSII does not have the ability to empty a polygon or create a hole.

The Advanced Design System can convert shapes with holes into contiguous single polygons by inserting an extra edge shown below.

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The first is “No data present”. I doubt anyone has had the chutzpah to start using it since. GDSII file instance names simplify the tracking of hierarchies within the file. Gsdii third data type is a “Two-Byte Signed Integer”. A component is flattened into its geometric primitives.

This is the one that seems to stgeam never been used, so I’ll describe the eight byte real in a bit more detail. The length of gdisi string is always equal to the length of the record minus the four bytes used for the record header. There is no explicitly stated limit to the level of hierarchy the degree of cell nesting ; however, most CAD programs impose a limit of around 32 levels. The record number is shown in brackets. Some examples from the book: As you can imagine, computers and processors have come a long way since that time; the specification has some constraints which were probably based both on the limitations of the 80’s era computers and also on the developer’s beliefs that chips were going to be approximately the same complexity for the foreseeable future.

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The leftmost bit of the first byte is valued atthe rightmost bit of the second byte is valued at 1. GDSII further employs user units in terms of number of user units to a meter.

While other formats have been proposed to replace it and one, OASIS, seems to be gaining some traction GDSII remains by far the main way of describing the physical layout for the masks used to build a chip.

The reference library names may include directory specifiers separated with “: This page was last edited on fprmat Novemberat If this record is omitted, then all bits are assumed to be 0. The following table summarizes the Bachus Naur symbols: Exactly 3 pairs 1: The fifth through last bytes of a record are data.