Signoff (electronic design automation): Difference between revisions

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{{Short description|Verification stages of electronic designs that must pass before manufacture}}

{{Use American English|date = April 2019}}

In the [[electronic design automation|automated]] design of [[integrated circuit]]s, '''signoff''' (also written as '''sign-off''') checks is the collective name given to a series of verification steps that the design must pass before it can be [[Tape-out|taped out]]. This implies an iterative process involving incremental fixes across the board using one or more check types, and then retesting the design. There are two types of sign-off's: [[front-end sign-off]] and [[back-end sign-off]]. After back-end sign-off, the chip goes to fabrication. After listing out all the features in the specification, the verification engineer will write coverage for those features to identify bugs, and send back the RTL design to the designer. Bugs, or defects, can include issues like missing features (comparing the layout to the specification), errors in design (typo and functional errors), etc. When the coverage reaches a maximum% percentage then the verification team will sign it off. By using a methodology like UVM, OVM, or VMM, the verification team develops a reusable environment. Nowadays, UVM is more popular than others.

== History ==

During the late 1960s engineers at semiconductor companies like Intel used [[rubylith]] for the production of semiconductor lithography photomasks. Manually drawn [[Circuit diagram|circuit draft schematics]] of the semiconductor devices made by engineers were transeferred manually onto [[Paper size|D-sized]] [[vellum]] sheets by a skilled schematic designer to make a physical layout of the device on a photomask.<ref name=":0">{{Cite journal |date=2001 |title=Recollections of Early Chip Development at Intel |url=https://deramp.com/downloads/mfe_archive/050-Component%20Specifications/Intel/Recollections%20of%20Early%20Chip%20Dev.pdf |journal=Intel technologyTechnology journalJournal |volume=5 |issue=2001 |issn=1535-864X}}</ref>{{r|:0|pp=6}}

The vellum would be later hand-checked and ''signed off'' by the original engineer; all edits to the schematics would also be noted, checked, and, again, ''signed off''.{{r|:0|pp=6}}