Editing Logic gate (section)

{{Short description|Device performing a Boolean function}}
{{Redirect|Discrete logic|discrete circuitry|Discrete circuit|discrete TTL logic|Transistor–transistor logic|the former image processing company|Discreet Logic}}
{{Use dmy dates|date=September 2022|cs1-dates=y}}
[[File:Four bit adder with carry lookahead.svg|thumb|A logic circuit diagram for a 4-bit [[Carry-lookahead adder|carry lookahead binary adder]] design using only the [[AND gate|AND]], [[OR gate|OR]], and [[XOR gate|XOR]] logic gates.|class=skin-invert-image]]

A '''logic gate''' is a device that performs a [[Boolean function]], a [[logical operation]] performed on one or more [[Binary number|binary]] inputs that produces a single binary output. Depending on the context, the term may refer to an '''ideal logic gate''', one that has, for instance, zero [[rise time]] and unlimited [[fan-out]], or it may refer to a non-ideal physical device<ref>{{cite book |author=Jaeger |title=Microelectronic Circuit Design |publisher=[[McGraw-Hill]] |date=1997 |isbn=0-07-032482-4 |pages=226–233}}</ref> (see [[ideal and real op-amps]] for comparison).

The primary way of building logic gates uses [[diode]]s or [[transistor]]s acting as [[electronic switches]]. Today, most logic gates are made from [[MOSFET]]s (metal–oxide–semiconductor [[field-effect transistor]]s).<ref name=kanellos >{{Cite web|url=https://www.cnet.com/news/moores-law-to-roll-on-for-another-decade/|title=Moore's Law to roll on for another decade|last=Kanellos|first=Michael|website=CNET|date=February 11, 2003}} ''From [[Integrated circuit]]''</ref> They can also be constructed using [[vacuum tube]]s, electromagnetic [[relay]]s with [[relay logic]], [[fluidic logic]], [[pneumatics#Pneumatic logic|pneumatic logic]], [[optics]], [[molecular logic gate|molecules]], acoustics,<ref>{{citation |url=https://pubs.aip.org/aip/apl/article-abstract/106/11/113503/27163/Acoustic-logic-gates-and-Boolean-operation-based?redirectedFrom=fulltext |title=Acoustic logic gates and Boolean operation based on self-collimating acoustic beams |date=2015 |doi=10.1063/1.4915338 |access-date=2024-08-17 |last1=Zhang |first1=Ting |last2=Cheng |first2=Ying |last3=Guo |first3=Jian-Zhong |last4=Xu |first4=Jian-yi |last5=Liu |first5=Xiao-jun |journal=Applied Physics Letters |volume=106 |issue=11 |bibcode=2015ApPhL.106k3503Z |url-access=subscription }}</ref> or even [[Analytical Engine|mechanical]] or thermal<ref>{{cite journal | url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.177208 | doi=10.1103/PhysRevLett.99.177208 | title=Thermal Logic Gates: Computation with Phonons | date=2007 | last1=Wang | first1=Lei | last2=Li | first2=Baowen | journal=Physical Review Letters | volume=99 | issue=17 | page=177208 | pmid=17995368 | arxiv=0709.0032 | bibcode=2007PhRvL..99q7208W | s2cid=10934270 }}</ref> elements.

Logic gates can be cascaded in the same way that Boolean functions can be composed, allowing the construction of a physical model of all of [[Boolean logic]], and therefore, all of the algorithms and [[mathematics]] that can be described with Boolean logic. '''Logic circuits''' include such devices as [[multiplexer]]s, [[processor register|registers]], [[arithmetic logic unit]]s (ALUs), and [[computer memory]], all the way up through complete [[microprocessor]]s,<ref>{{cite book | url=https://books.google.com/books?id=GBVADQAAQBAJ&q=processor+logic+gates | title=Digital Systems: From Logic Gates to Processors | isbn=978-3-319-41198-9 | last1=Deschamps | first1=Jean-Pierre | last2=Valderrama | first2=Elena | last3=Terés | first3=Lluís | date=12 October 2016 | publisher=Springer }}</ref> which may contain more than 100 million logic gates.

Compound logic gates [[AND-OR-Invert]] (AOI) and [[OR-AND-invert|OR-AND-Invert]] (OAI) are often employed in circuit design because their construction using MOSFETs is simpler and more efficient than the sum of the individual gates.<ref>{{cite book |title=Engineering digital design |edition=2nd |author-last=Tinder |author-first=Richard F. |date=2000 |isbn=0-12-691295-5 |pages=317–319 |publisher=Academic Press |url=https://books.google.com/books?id=6x0pjjMKRh0C&q=AOI+gate&pg=PT347}}</ref>