**Logic gates** are the basic building blocks of digital circuits. They perform simple logical operations on one or more binary inputs and produce a single binary output.

## Types of Logic gates:

There are **seven **types of logic gates:

- AND gate
- OR gate
- NOT gate
- NAND gate
- NOR gate
- XOR gate
- XNOR gate

## • AND Gate:

An **AND gate** is a digital logic gate that performs the logical conjunction operation. The output of an AND gate is true (1) only when all of its inputs are true (1); otherwise, the output is false (0).

• This gate has a minimum of **2 input **values and a **single output** value.

## ‣ Logical Circuit:

## ‣ Truth Table:

## • OR Gate:

An **OR gate** is a digital logic gate that performs the logical disjunction operation. The output of an OR gate is true (1) if at least one of its inputs is true (1); otherwise, the output is false (0).

• This gate also has a minimum of** 2 input** values and a **single output** value.

## ‣ Logical circuit:

## ‣ Truth Table:

## • NOT Gate:

A **NOT gate **is a digital logic gate that performs the logical negation operation. If the input is true (1), the output is false (0), and if the input is false (0), the output is true (1).

• It is also known as **inverter**.

• This gate has only **one input **and **one output** value.

## ‣ Logical Circuit:

## ‣ Truth Table:

## • NAND Gate:

A **NAND gate** is a digital logic gate that performs the logical negation of the AND operation. If all the inputs of NAND gate are True(1), then the output will be false(0), otherwise True(1).

• The NAND gate is the **universal gate** because all the basic gates such as AND, OR, and NOT gate can be constructed using a NAND gate.

• The NAND gate is the combination of the NOT-AND gate.

## ‣ Logical Circuit:

## ‣ Truth Table:

## » AND Gate using NAND Gate:

## » OR Gate using NAND Gate:

## » NOT Gate using NAND Gate:

## • NOR Gate:

A** NOR gate** is a digital logic gate that performs the logical negation of the OR operation. The output of a NOR gate is true (1) only when none of its inputs are true (1); otherwise, the output is false (0).

• It is also a **universal gate** because all the basic gates such as AND, OR, and NOT gate can be constructed using a NOR gate.

• The NOR gate is the combination of the **NOT-OR gate**.

## ‣ Logical Circuit:

## ‣ Truth Table:

## » AND Gate using NOR Gate:

## » OR Gate using NOR Gate:

## » NOT Gate using NOR Gate:

## • XOR Gate:

An **XOR gate**, or** exclusive OR** **gate**, is a digital logic gate that performs the logical exclusive disjunction operation. It produces a True(1) output only if one of its inputs is True and the other is false.

• It is a hybrids gate.

## ‣ Logical Circuit:

## ‣ Truth Table:

## • XNOR Gate:

An **XNOR gate**, or **exclusive NOR gate**, is a digital logic gate that performs the logical equivalence operation.The output of an XNOR gate is true (1) if both inputs are the same (either both true or both false); otherwise, the output is false (0).

• It is also a **hybirds gate**.

• The XNOR gate is also called the **Equivalence gate**.