Digital logic, an Inverter or NOT gate Digital logic, an Inverter or NOT gate | Page 6

INTRODUCTION
Logic gates are the basic building blocks of digital logic circuits as well as digital
electronics. A gate is defined as a logic device which computes functionally on a
2 valued input signal. Logic gates are of many types such as OR, AND, NOR,
NAND, EX –OR and NOT etc. Among these, all gates have two inputs and one
output except NOT gate. NOT gate has only one input and one output. This gate
produces the reverse output of applied input. So this gate is also called as ‘Digital
Inverter’.
NOT Gate Logic Symbol and Boolean Expression
We know the NOT gate is an inverter, which inverts or reverses the input.. So
the output is represented by ‘-’ bar symbol of the input. The Boolean expression
of the NOT gate is Z =X . ̅ Pronounced as “Z is equal to X bar”. The logic symbol of
the NOT gate is shown in below figure.
If X is the input and Z is the output, then if X = 0, then Z = 1
If X = 1, then Z = 0.