NOT gate

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INPUT
A		 OUTPUT
NOT A
0 1
1 0

The NOT gate or inverter is a digital logic gate that implements logical negation. It behaves according to the truth table to the right. A LOW input (1) results if the output is HIGH (0); similarly, if the input is HIGH (1), a LOW output (0) results.

Contents

[edit] Symbols

There are two symbols for NOT gates: the "military" symbol and the "rectangular" symbol. For more information see Logic Gate Symbols.

'Military' NOT symbol
'Military' NOT symbol
'Rectangular' NOT symbol
'Rectangular' NOT symbol



This schematic diagram shows the arrangement of NOT gates within a standard 4049 CMOS hex inverting buffer.
This schematic diagram shows the arrangement of NOT gates within a standard 4049 CMOS hex inverting buffer.

[edit] Hardware description and pinout

NOT Gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs. The standard, 4000 series, CMOS IC is the 4049, which includes six independent NOT gates. The pinout diagram is as follows:

This device is available from most semiconductor manufacturers such as Philips. It is usually available in both through-hole DIL and SOIC format. Datasheets are readily available in most Datasheet Databases.

[edit] Implementations

NMOS NOT gate
NMOS NOT gate
PMOS NOT gate
PMOS NOT gate
Transistor-Transistor logic NOT gate
Transistor-Transistor logic NOT gate

[edit] Alternatives

NOT gate constructed using only a NAND gate
NOT gate constructed using only a NAND gate

If no specific NOT gates are available, one can be made from NAND gates in the configuration shown below. Alternatively, a NOR gate could be used in the same configuration. Any logic gate can be made from a combination of NAND gates or NOR gates.

[edit] See also