Cadence Design Framework II
All the tools from cadence for the VLSI design process use the same unique database called Design Framework II (DFII). It is a binary database that stores the data as objects. In the world of Electronic Design Automation (EDA), there are different types of objects and each representing a distinct concept. The cellviews, symbols, instances, terminals etc are different types of objects. The Design Framework II database can store both the physical information as well as the logical information of a design. The physical information includes geometrical shapes of IC layout. Logical information includes nets and schematics, which can exist without any corresponding physical realizations. The Design Framework II supports two database types: CDBA and OpenAccess. There is a function to determine the database type.
The function will return either CDBA or OpenAccess (OA) depending on which database type is supported by the current executable.
What is OpenAccess Database?
There are large number of processes required, to reach up to the fabrication of an IC. The processing steps starting from the Register Transfer Level to the GDS II format. During various levels of the designing process, various tools from different vendors are using to get the most accurate result. The tool from a particular vendor used at any level may not be used in the next level. So some other supporting files and extra time required to convert the data compactable for the next one. If all the vendors use the same platform for all the tools, then it will come to a simpler equation. Hence the cost and complexity can be reduced. When this suggestion arises among the silicon companies who manufacture most of the tools, the idea of OpenAccess database is introduced. Now 36 major companies are the members of the OpenAccess forum, which are the leading companies in the Semiconductor, EDA, and electronics field. They include Altera, Intel Corporation, IBM Corporation, Cadence design systems, Mentor Graphics, NXP, Synopsys, Sun Microsystems etc.
What is CDBA?
CDBA is a cadence specific database, and can be expanded as Cadence Data Base Access. It is developed by cadence itself to make their tools and software. dbWriteSkill was an earlier one to the OpenAccess. They also developed dbWriteSkill which is intended to help Cadence Pcell developers, for Cadence-specific database (CDBA). The cadence-specific database is also made compactable with the OA with the help of SKILL. The SKILL code which includes dbWriteSkill, has been made almost 100% cross compactable between CDBA and OA. That is the same translator can be used to convert CDBA to OA and vice versa. It is the best method and is oftenly used. For translating OA back to the CDBA database this is the only way. In other words the SKILL code can be considered as the source and can be compiled to any database including OA and CDBA.