Alternative Logic Gates (XOR, XNOR Gate)

We also have some alternative logic gates that are used very frequently in digital circuits.

The most basic of them are:

• XOR Gate
• XNOR Gate 

1)  XOR GATE

   XOR Gate (or EXOR Gate) stands for Exclusive-OR Gate. In Exclusive-OR Gate if one and only one of the inputs is high (1) then the output is high (1) else the output is low (0). In simpler words, when the inputs are not similar then the output is high (1) and when the inputs are alike then the output is low (0). As it represents the inequality function, it is also called inequality detector.

Logical Expression

F = A ⊕ B = AB’ + A’B

Logical Symbol

The logic symbol for XOR Gate is given below:

Truth Table

                                                                

2)  XNOR GATE  

   X-NOR Gate (or EX-NOR Gate) stands for Exclusive-NOR Gate. EX-NOR Gate is an XOR Gate followed by a NOT Gate. In Exclusive-NOR Gate if ALL OF the inputs are either high (1) or low (0) then the output is high (1) else the output is low (0). In simpler words, when the inputs are similar then the output is high (1) and when the inputs are not alike then the output is low (0). Here the outputs are opposite of that of an XOR Gate.

Logical Expression

F = (A ⊕ B)’ = AB + A’B’

Logical Symbol

The logical symbol of XNOR Gate s given below:

Truth Table