Logic Gates-
Before you go through this article, make sure that you have gone through the previous article on Logic Gates.
We have discussed-
- Logic gates are the basic building blocks of any digital circuit.
- There are 3 basic logic gates- AND, NOT, OR.
- Logic gates are classified as-
In this article, we will discuss about Universal Logic Gates.
Universal Logic Gates-
| Universal logic gates are the logic gates that are capable of implementing any Boolean function
without requiring any other type of gate. |
They are called as “Universal Gates” because-
- They can realize all the binary operations.
- All the basic logic gates can be derived from them.
They have the following properties-
- Universal gates are not associative in nature.
- Universal gates are commutative in nature.
There are following two universal logic gates-
- NAND Gate
- NOR Gate
1. NAND Gate-
- A NAND Gate is constructed by connecting a NOT Gate at the output terminal of the AND Gate.
- The output of NAND gate is high (‘1’) if at least one of its inputs is low (‘0’).
- The output of NAND gate is low (‘0’) if all of its inputs are high (‘1’).
Logic Symbol-
The logic symbol for NAND Gate is as shown below-
Truth Table-
The truth table for NAND Gate is as shown below-
| A | B | Y = (A.B)’ |
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
Truth Table
Timing Diagram-
The timing diagram for NAND Gate is as shown below-
2. NOR Gate-
- A NOR Gate is constructed by connecting a NOT Gate at the output terminal of the OR Gate.
- The output of OR gate is high (‘1’) if all of its inputs are low (‘0’).
- The output of OR gate is low (‘0’) if any of its inputs is high (‘1’).
Logic Symbol-
The logic symbol for NOR Gate is as shown below-
Truth Table-
The truth table for NOR Gate is as shown below-
| A | B | Y = A + B |
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
Truth Table
Timing Diagram-
The timing diagram for NOR Gate is as shown below-
To gain better understanding about Universal Logic Gates,
Next Article- Alternative Logic Gates
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