GDSII
Encyclopedia
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
file format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
which is the de facto industry standard for data exchange of integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
or IC layout artwork. It is a binary file
Binary file
A binary file is a computer file which may contain any type of data, encoded in binary form for computer storage and processing purposes; for example, computer document files containing formatted text...
format representing planar geometric shapes, text labels, and other information about the layout in hierarchical form. 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 photomask
Photomask
A photomask is an opaque plate with holes or transparencies that allow light to shine through in a defined pattern. They are commonly used in photolithography.-Overview:...
s.
History of the GDSII format
GDS = Graphic Database SystemInitially, GDSII was designed as a format used to control integrated circuit photomask plotting. Despite its limited set of features and low data density, it became the industry conventional format for transfer of IC layout data between design tools of different vendors, all of which operated with proprietary data formats.
It was originally developed by Calma
Calma
Calma Company, based in Sunnyvale, California, was, between 1965 and 1988, a vendor of digitizers and minicomputer-based graphics systems targeted at the cartographic and electronic, mechanical and architectural design markets....
for its layout design software, "Graphic Data System" ("GDS") and "GDSII". Now the format is owned by Cadence Design Systems
Cadence Design Systems
Cadence Design Systems, Inc is an electronic design automation software and engineering services company, founded in 1988 by the merger of SDA Systems and ECAD, Inc...
.
GDS II files are usually the final output product of the IC design cycle and are given to IC foundries for IC fabrication. GDS II files were originally placed on magnetic tape
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
s. This moment was fittingly called tape out though it is not the original root of the term.
Objects contained in a GDSII file are grouped by assigning numeric attributes to them including a "layer number", "datatype" or "texttype". While these attributes were designed to correspond to the "layers of material" used in manufacturing an integrated circuit, their meaning rapidly became more abstract to reflect the way that the physical layout
Integrated circuit layout
Integrated circuit layout, also known IC layout, IC mask layout, or mask design, is the representation of an integrated circuit in terms of planar geometric shapes which correspond to the patterns of metal, oxide, or semiconductor layers that make up the components of the integrated circuit.When...
is designed.
As of October 2004, many EDA
Electronic design automation
Electronic design automation is a category of software tools for designing electronic systems such as printed circuit boards and integrated circuits...
software vendors have begun to support a new format, OASIS
Open Artwork System Interchange Standard
OASIS is a language used by computers to represent and express an electronic pattern for an integrated circuit during its design and manufacture. The language defines the code required for geometric shapes such as polygons, rectangles and trapezoids...
, which may replace GDSII.
GDSII utilities
As the GDSII stream format is a de facto standard, it is supported by nearly all EDA software. Besides the commercial vendors there are plenty of free GDSII utilities. These free tools include editors, viewers, utilities to convert the 2D layout data into common 3D formats, utilities to convert the binary format to a human readable ASCII format and program libraries.See also
- Computer Aids for VLSI Design - Appendix C: GDS II Format by Steven M. Rubin
- The GDSII Stream Format by Jim Buchanan
- List of various layout editors/viewers
- Caltech Intermediate FormCaltech Intermediate FormCaltech Intermediate Form is a file format for describing integrated circuits.CIF provides a limited set of graphics primitives that are useful for describing the two-dimensionalshapes on the different layers of a chip....
- OASIS (Open Artwork System Interchange Standard)