GDSII STREAM FORMAT PDF
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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CHAPTER 1 GDSII format
Contains the list of layers and data types included in the data file usually as specified by the user when generating the Stream file. If this record is omitted, then all bits are assumed to be 0. The records shown within square brackets ‘’ are optional. The first two bytes of the record header contain a count in eight-bit bytes of the total record length.
They sure did that with the layer numbers and data types. Layers and datatypes used for mask in a filtered stream file.
Objects contained in a GDSII file are grouped by assigning numeric attributes to them including a “layer number”, “datatype” or “texttype”. GDSII limitations can affect how you design your layout. Two-byet signed integer 2. Square ended paths 1: The names of the layers and its appearance in the design is not stored.
The first two bytes of the header contain a count in eight-bit bytes of the total record length. This record must be present if there are any reference libraries bound to the current library. The Advanced Design System can convert shapes with holes into contiguous single polygons by inserting an extra edge shown below.
Each name is padded with nulls if it is shorter than 44 bytes. GDS II files were originally placed on magnetic tapes. GDSII interpreters will either impose such a limit explicitly, or will impose an implicit limit by running out of memory during recursive operations.
A component is flattened into its geometric primitives. The elements within braces must occur one or more times. Path and boundary elements may have up to pairs of coordinates.
This marks the end of a structure. For Layer Editor options, see Defining Layers.
GDS II (Calma GDS II)
BOX [2D00] No data is present. This marks the beginning of a structure reference element a reference or “call” to another cell in the library. The third byte of the header is the record type also known as a “token”. The third byte is the record type. An array of coordinates in data base units. For example, if a design contains an MLIN it will be flattened.
For example, if a boundary element used a property attribute 2 with property value “metal”, and property attribute 10 with property value “property”, then the total amount of property data would be 18 bytes. Maximum size is 44 bytes. Had 1 to 32 entries with group numbers, user numbers and access rights.
The GDSII Stream Format
Neither the number of columns nor the number of rows may exceed 32, decimal and both are positive. Two 2 byte integers. Information about external data can be found in the CustomPlus User’s Manual.
From Wikipedia, the free encyclopedia. If it is set, then reflection about the X axis is applied before angular rotation. Therefore, some consideration should be given to the use of curved elements and the extensive use of arcs and circles in your layout design.
There are values for such things as the beginning of a structure, the beginning of a boundary, the end of a structure, and so on. The decimal point of the binary mantissa is just to the left of bit 8. 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 streqm used to build a chip.
The data can be used to reconstruct all or part of the flrmat to be used in sharing layouts, transferring artwork between different tools, or creating photomasks. GDSII has some limitations that may affect your layout, including: Webarchive template wayback links.
NODE  No data is present. I haven’t seen this since the days of 9 track tapes on reels, but just in case, here we go This informationis used only when atream the data into a new library. The program stores arcs as true arcs.
An element shown in lower case means that name can be further broken down in to a set of record types. The fifth data type is the “Four-Byte Real”. The next record begins immediately after the last byte included in the count. Note Because the GDSII stream is a block-structured binary file, it can easily be corrupted when transferring the file from one system to another. GDSII further employs user units in terms of number of user units to a meter.
Objects in the cell are assigned to “layers” of the design. The fourth, and last, byte in the steeam header is the data type. When transferring a file via tape, the block size must be preserved.
The default value for this option is Individual layers or data types are separated with a space.