Negated AND gate

Negated AND gate
A   B
0 0 1
0 1 1
1 0 1
1 1 0
NAND Full adder

The Negated AND, NO AND or NAND gate is the opposite of the digital AND gate, and behaves in a manner that corresponds to the opposite of AND gate, as shown in the truth table on the left. A LOW output results only if both the inputs to the gate are HIGH. If one or both inputs are LOW, a HIGH output results.

The NAND gate is significant because any boolean function can be implemented by using a combination of NAND gates. This property is called functional completeness.

Digital systems employing certain logic circuits take advantage of NAND's functional completeness. In complicated logical expressions, normally written in terms of other logic functions such as AND, OR, and NOT, writing these in terms of NAND saves on cost, because implementing such circuits using NAND gate yields a more compact result than the alternatives.

NAND gates can also be made with more than two inputs, yielding an output of LOW if all of the inputs are HIGH, and an output of HIGH if any of the inputs is LOW. These kinds of gates therefore operate as n-ary operators instead of a simple binary operator. Algebraically, these can be expressed as the function NAND(a, b, ..., n), which is logically equivalent to NOT(a AND b AND ... AND n).



There are three symbols for NAND gates: the 'distinctive' (MIL/ANSI) symbol and the 'rectangular' IEC symbol, as well as a deprecated DIN symbol sometimes found on old schematics. For more information see logic gate symbols.

NAND ANSI Labelled.svg NAND IEC.svg NAND DIN.svg
MIL/ANSI Symbol' IEC Symbol DIN Symbol

Hardware description and pinout

NAND gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs.

This schematic diagram shows the arrangement of NAND gates within a standard 4011 CMOS integrated circuit.

CMOS version

The standard, 4000 series, CMOS IC is the 4011, which includes four independent, two-input, NAND gates.


These devices are available from most semiconductor manufacturers such as Fairchild Semiconductor, Philips or Texas Instruments. These are usually available in both through-hole DIL and SOIC format. Datasheets are readily available in most datasheet databases.

The standard 2-, 3-, 4- and 8-input NAND gates are available:

  • CMOS
    • 4011: Quad 2-input NAND gate
    • 4023: Triple 3-input NAND gate
    • 4012: Dual 4-input NAND gate
    • 4068: Mono 8-input NAND gate
  • TTL
    • 7400: Quad 2-input NAND gate
    • 7410: Triple 3-input NAND gate
    • 7420: Dual 4-input NAND gate
    • 7430: Mono 8-input NAND gate


The NAND gate has the property of functional completeness. That is, any other logic function (AND, OR, etc.) can be implemented using only NAND gates. An entire processor can be created using NAND gates alone. In TTL ICs using multiple-emitter transistors, it also requires fewer transistors than any other gate.

The physical layout of a CMOS NAND

See also

External links

Wikimedia Foundation. 2010.

Нужно решить контрольную?

Look at other dictionaries:

  • Logic gate — A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal… …   Wikipedia

  • Anthropology and Archaeology — ▪ 2009 Introduction Anthropology       Among the key developments in 2008 in the field of physical anthropology was the discovery by a large interdisciplinary team of Spanish and American scientists in northern Spain of a partial mandible (lower… …   Universalium

  • Track and Field Sports — ▪ 2007 Introduction World Indoor Championships.       At the International Association of Athletics Federations (IAAF) world indoor championships, held in Moscow on March 10–12, 2006, Russia and the U.S. divided up a majority share of the gold… …   Universalium

  • ne|gate — «nih GAYT, NEE gayt», transitive verb, gat|ed, gat|ing. 1. to destroy, nullify, or make ineffective: »If gravity can be understood scientifically and negated or neutralized in some relatively inexpensive manner... (New York Herald Tribune). 2. to …   Useful english dictionary

  • Sheffer stroke — This article is about the logical NAND operator. For the electronic NAND gate, see Negated AND gate. For other uses, see Nand (disambiguation). Venn diagram of In Boolean functions and propositional calculus, the Sheffer stroke, named after …   Wikipedia

  • Boolean algebra (logic) — For other uses, see Boolean algebra (disambiguation). Boolean algebra (or Boolean logic) is a logical calculus of truth values, developed by George Boole in the 1840s. It resembles the algebra of real numbers, but with the numeric operations of… …   Wikipedia

  • Boolean algebra — This article discusses the subject referred to as Boolean algebra. For the mathematical objects, see Boolean algebra (structure). Boolean algebra, as developed in 1854 by George Boole in his book An Investigation of the Laws of Thought,[1] is a… …   Wikipedia

  • Digital delay generator — A digital delay generator is a piece of electronic test equipment that provides precise delays for triggering, syncing, delaying and gating events. These generators are used in many types of experiments, controls and processes where electronic… …   Wikipedia

  • Boolean algebra (introduction) — Boolean algebra, developed in 1854 by George Boole in his book An Investigation of the Laws of Thought , is a variant of ordinary algebra as taught in high school. Boolean algebra differs from ordinary algebra in three ways: in the values that… …   Wikipedia

  • Gerakas — Infobox Greek Dimos name = Gerakas name local = Γέρακας image coa = periph = Attica prefec = East Attica province = population = 13921 population as of = 2001 population ref = [ tables/S1101 SAP 1 TB DC 01 03 Y.pdf… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”