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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Validate File A file validation is performed after any save operation. As a workaround it is possible to save polygons in multi-records and avoid that limit. This record must be present if gdsii of the 4 fonts have a corresponding textfont definition file. Therefore, some consideration should be given to the use of curved elements and the extensive use of arcs and circles in your layout design.
CHAPTER 1 GDSII format
Unfortunately, when one needs to compute the actual position of the polygonal entities, one must “reverse” this nesting; for large databases this turns out to be a difficult computation to do quickly. The following is a list of stteam types. The following record types are either not used, not released, or are related to tape formatting: Different layers typically represent different processing steps for exposure on separate mask plates.
GDSII interpreters will either impose such a limit explicitly, or will gdaii an implicit limit by running out of memory during recursive operations.
GDSII is organized in a hierarchical fashion.
Valid values are 1 – inclusive. Improvements and Enhancements since ? If a character string is an odd number of bytes long foramt is padded with a null character.
This record must not be present if none of the fonts have a textfont file. If this number is not even, a NULL character 0x00 is added to the end.
For every hex digit shifted, strean exponent is decreased by one. The value can be negative. BOX [2D00] No data is present. Bit 13 flags absolute magnification. Print version of this Book PDF file.
GDSII path is imported as an ADS path with square corner type resulting in the loss of data in the path’s round-ended endpoints and corners. No support for arcs or circles No support for holes or empty regions character name limitation Limit of mask layers Curved Element Limitation Although the Advanced Design System has options for re-mapping layer numbers and structure names, it does not have gvsii full ability to overcome the GDSII limitations regarding curved elements.
Two-byet signed integer 2.
GDSII – Wikipedia
The first two bytes of the record header contain a stram in eight-bit bytes of the total record length. Cells can be nested with no limitation as to how deep the nesting goes though I have yet to see nesting more than 9 levels deep. Since the formxt is shifted four bits at a time, it is possible for the left three bits of a normalized mantissa to be zero.
Since knowing the library structure without knowing about records and data types would be of marginal use, and knowing about records and data types without knowing about the library structure would be worse, you might have to scan through this s few times before it makes sense.
The LayoutEditor can gdeii layer names by a non-standard extension see below.
GDS II (Calma GDS II)
NODE  No data is present. Webarchive template wayback links. Values are 0, 3, 4, 5, and Real numbers are not represented in IEEE format.
Sream remaining 7 bytes are the mantissa, with a binary point to the left of the most significant figure. No data is present. Although the number of vertices used to approximate an arc strem be controlled via the Arc Resolution dialog box see Curved Element Limitationthe vertices limit may prevent the program from correctly evaluating polygons consisting of several arcs. Seems a bit odd in an archive The representation of negative numbers is the same as that of positive numbers, except that the highest order bit is 1, not 0.
Lack of Support for Holes Lack of support for holes is usually not a problem, but should be considered. Maximum length is characters. If this record is omitted, then the element is assumed to have no reflection and its magnification and angle are assumed to be non-absolute. Colors, and style of the layer are stored as attributes of the text element.
This information is used only when reading the data into a new library. For these systems, select Holes As Polygons. This enables you to define the maximum number of vertices allowed for one polygon.
This one gets a little more use. To calculate the size of a user unit in meters, divide the second number by the first. This is not part of the GDS standard, but supported by some viewers. This option is useful when your post-processor does not support or correctly translate hierarchy in GDSII Stream files. The data can be used to reconstruct all or part of the artwork to be used in sharing layouts, transferring artwork between different tools, or creating photomasks.
This appendix omits the description of streak formatting, since disk files and disk file images on tape and other media are now the norm .