Very-large-scale integration (VLSI) is the process of creating integrated circuits by combining thousands of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device.
The first semiconductor chips held two transistors each. Subsequent advances added more and more transistors, and, as a consequence, more individual functions or systems were integrated over time. The first integrated circuits held only a few devices, perhaps as many as ten diodes, transistors, resistors and capacitors, making it possible to fabricate one or more logic gates on a single device. Now known retrospectively as ''small-scale integration'' (SSI), improvements in technique led to devices with hundreds of logic gates, known as ''medium-scale integration'' (MSI). Further improvements led to ''large-scale integration'' (LSI), i.e. systems with at least a thousand logic gates. Current technology has moved far past this mark and today's microprocessors have many millions of gates and billions of individual transistors.
At one time, there was an effort to name and calibrate various levels of large-scale integration above VLSI. Terms like ''ultra-large-scale integration'' (ULSI) were used. But the huge number of gates and transistors available on common devices has rendered such fine distinctions moot. Terms suggesting greater than VLSI levels of integration are no longer in widespread use.
As of early 2008, billion-transistor processors are commercially available. This is expected to become more commonplace as semiconductor fabrication moves from the current generation of 65 nm processes to the next 45 nm generations (while experiencing new challenges such as increased variation across process corners). A notable example is Nvidia's 280 series GPU. This GPU is unique in the fact that almost all of its 1.4 billion transistors are used for logic, in contrast to the Itanium, whose large transistor count is largely due to its 24 MB L3 cache. Current designs, as opposed to the earliest devices, use extensive design automation and automated logic synthesis to lay out the transistors, enabling higher levels of complexity in the resulting logic functionality. Certain high-performance logic blocks like the SRAM (Static Random Access Memory) cell, however, are still designed by hand to ensure the highest efficiency (sometimes by bending or breaking established design rules to obtain the last bit of performance by trading stability).
Structured VLSI design had been popular in the early 1980s, but lost its popularity later because of the advent of placement and routing tools wasting a lot of area by routing, which is tolerated because of the progress of Moore's Law. When introducing the hardware description language KARL in the mid' 1970s, Reiner Hartenstein coined the term "structured VLSI design" (originally as "structured LSI design"), echoing Edsger Dijkstra's structured programming approach by procedure nesting to avoid chaotic ''spaghetti-structured'' programs.
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Category:Telecommunications engineering Category:Electronic engineering Category:Integrated circuits
ar:دارات التكامل الفائق bn:ভেরি-লার্জ-স্কেল ইন্টিগ্রেশন bs:VLSI ca:VLSI cs:Very-large-scale integration de:Integrationsgrad es:Integración a muy gran escala eu:VLSI fr:Intégration à très grande échelle ko:초고밀도 집적회로 hr:VLSI it:Very large scale integration he:VLSI ms:Penyepaduan skala sangat besar ru:Интегральная схема#Степень интеграции tr:Çok Geniş Ölçekli TümleşimThis text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
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