Editing Logic gate (section)

==== Logic families ====
{{Main| Logic family}}
There are several [[logic families]] with different characteristics (power consumption, speed, cost, size) such as: [[diode logic|RDL]] (resistor–diode logic), [[resistor–transistor logic|RTL]] (resistor-transistor logic), [[DTL]] (diode–transistor logic), [[transistor–transistor logic|TTL]] (transistor–transistor logic) and CMOS. There are also sub-variants, e.g. standard CMOS logic vs. advanced types using still CMOS technology, but with some optimizations for avoiding loss of speed due to slower PMOS transistors.

The simplest family of logic gates uses [[bipolar transistors]], and is called [[resistor–transistor logic]] (RTL). Unlike simple diode logic gates (which do not have a gain element), RTL gates can be cascaded indefinitely to produce more complex logic functions. RTL gates were used in early [[integrated circuit]]s. For higher speed and better density, the resistors used in RTL were replaced by diodes resulting in [[diode–transistor logic]] (DTL). [[Transistor–transistor logic]] (TTL) then supplanted DTL.

[[File:CMOS inverter.svg|thumb|125px|[[CMOS]] diagram of a [[NOT gate]], also known as an inverter. [[MOSFET]]s are the most common way to make logic gates.]]
As integrated circuits became more complex, bipolar transistors were replaced with smaller [[field-effect transistor]]s ([[MOSFET]]s); see [[PMOS logic|PMOS]] and [[NMOS logic|NMOS]]. To reduce power consumption still further, most contemporary chip implementations of digital systems now use [[CMOS]] logic.  CMOS uses complementary (both n-channel and p-channel) MOSFET devices to achieve a high speed with low power dissipation.

Other types of logic gates include, but are not limited to:<ref>{{cite news |author-last=Rowe |author-first=Jim |title=Circuit Logic – Why and How |agency=Electronics Australia |issue=December 1966}}</ref>

{| class="wikitable"
|+ 
! Logic family !! Abbreviation !! Description
|-
| [[Diode logic]]|| DL || 
|-
| Tunnel diode logic || TDL || Exactly the same as diode logic but can perform at a higher speed.{{failed verification|reason=Tunnel diodes have gain and state|date=December 2017}}
|-
| Neon logic || NL || Uses neon bulbs or 3-element neon trigger tubes to perform logic.
|-
| Core diode logic || CDL || Performed by semiconductor diodes and small ferrite toroidal cores for moderate speed and moderate power level.
|-
| 4Layer Device Logic || 4LDL || Uses thyristors and SCRs to perform logic operations where high current and or high voltages are required.
|-
| [[Direct-coupled transistor logic]] || DCTL || Uses transistors switching between saturated and cutoff states to perform logic. The transistors require carefully controlled parameters. Economical because few other components are needed, but tends to be susceptible to noise because of the lower voltage levels employed. Often considered to be the father to modern TTL logic.
|-
| [[Metal–oxide–semiconductor]] logic || MOS || Uses [[MOSFET]]s (metal–oxide–semiconductor field-effect transistors), the basis for most modern logic gates. The MOS logic family includes [[PMOS logic]], [[NMOS logic]], [[complementary MOS]] (CMOS), and [[BiCMOS]] (bipolar CMOS).
|-
| [[Current-mode logic]] || CML || Uses transistors to perform logic but biasing is from constant current sources to prevent saturation and allow extremely fast switching. Has high noise immunity despite fairly low logic levels.
|-
| [[Quantum dot cellular automaton|Quantum-dot cellular automata]]
| QCA
| Uses tunnelable q-bits for synthesizing the binary logic bits. The electrostatic repulsive force in between two electrons in the quantum dots assigns the electron configurations (that defines state 1 or state 0) under the suitably driven polarizations. This is a transistorless, currentless, junctionless binary logic synthesis technique allowing it to have very fast operation speeds.
|-
| Ferroelectric FET || FeFET || FeFET transistors can retain their state to speed recovery in case of a power loss.<ref>{{cite web | url=https://semiengineering.com/tapping-into-non-volatile-logic/ | title=Tapping into Non-Volatile Logic | date=21 April 2021 }}</ref>
|}