# Electronics/Basic gates

## Basic Gates

There are 5 basic gates used in performing logic operations in Digital Electronic namely BUFFER gate, NOT gate, AND gate, OR gate, XOR gate . Each Logic Gate has A Symbol for easy to identify , a Mathematical Expression to identify mathematic logic operation and a Truth Table to completely describe operation of the Logic Gate

## Five Basic Logic Gates

Digital gates Symbol Logic Operation Mathematic Expression
BUFFER   Y = BUFFER A Y = A
NOT   Y = NOT A Y = ${\bar {A}}$
AND   Y = A AND B Y = A . B
OR   Y = A OR B Y = A + B
XOR   Y = A XOR B Y = ${A\oplus B}$

The Truth Table of the five basic logic gates above

A B Q = A Q = NOT A Q = A AND B Q = A OR B Q = A XOR B
0 0 0 1 0 0 0
0 1 0 1 0 1 1
1 0 1 0 0 1 1
1 1 1 0 1 1 0

## Complement of Basic Logic gates

Basic Gates Combination Gates Symbol Mathematical Expression
BUFFER       Q = is NOT NOT A
Y = A
NOT       Y = is NOT A
NAND       Q = NOT A AND B
NOR       Y = NOT A OR B
XNOR       Q = NOT A XOR B

The Truth table of the combination gates above

A B Q = A Q = NOT A Q = A NAND B Q = A NOR B Q = A XNOR B
0 0 0 1 1 1 1
0 1 0 1 1 0 0
1 0 1 0 1 0 0
1 1 1 0 0 0 1

## Summary

Gates Function Symbol
ANSI IEC
Buffer $Q=A$
NOT gate (Inverter) $Q={\overline {A}}$
AND gate $Q=A\cdot B$
NAND gate (NOT−AND) $Q={\overline {A\cdot B}}$
OR gate $Q=A+B$
NOR gate (NOT−OR) $Q={\overline {A+B}}$
XOR gate (Exclusive-OR) $Q=A\oplus B$
XNOR gate (NOT−exclusive−OR) $Q={\overline {A\oplus B}}$
A B Q = A Q = NOT A Q = A AND B Q = A OR B Q = A XOR B Q = A NAND B Q = A NOR B Q = A XNOR B
0 0 0 1 0 0 0 1 1 1
0 1 0 1 0 1 1 1 0 0
1 0 1 0 0 1 1 1 0 0
1 1 1 0 1 1 0 0 0 1