A logic gate is a physical device implementing a Boolean function. Logics gates instant decisions depending on the inputs. There are three types of logics AND, OR & NOT and can be expressed in Algebraic form

Now, most of the Logic gates are implemented using MOSFETs (metal–oxide–semiconductor field-effect transistors). But can also be constructed using vacuum tubes, electromagnetic relays (relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical elements.

AND Logic Gate

AND logic gate is similar to an arithmetic multiplication operation, It performs the following operations

Produces a logic HIGH output when both the inputs are HIGH

Produces a logic LOW output when any one input or both the input are LOW

Truth Table

X

Y

X AND Y

0

0

0

0

1

0

1

0

0

1

1

1

Logic diagram

OR Logic Gate

OR gate acts as a selector and it always selects the highest possible output from input

Produces an logic high output when any one input is high

Produces an logic low output when both the inputs are low

Truth Table

X

Y

X OR Y

0

0

0

0

1

1

1

0

1

1

1

1

Logic diagram

NOT Logic Gate

Produces a complement output for the given input

produces a 0 when input is 1 and produces an output 1 when input is 0

Truth Table

X

NOT A

0

1

1

0

Logic diagram

NOR Logic Gate

NOR is a universal gate

Produces an logic HIGH output when both inputs are LOW

Produces an logic LOW output when any one input is HIGH

Truth table and logic diagram

NAND Logic Gate

NAND is a universal gate

Produces an logic HIGH output when any one input is LOW

Produces an logic LOW output when both the inputs are at logic HIGH

XOR Logic Gate

The output is HIGH if either input X or input Y is HIGH

The output is LOW when both are the same.

TRUTH TABLE

Input 1

Input 2

Output

X

Y

Z

0

0

0

0

1

1

1

0

1

1

1

0

Logic diagram

XNOR Logic Gate

If both input X and Y are same then the output is high