This document discusses different types of logic gates that are used as building blocks for digital circuits. It describes the AND, OR, NAND, NOR, and EXCLUSIVE NOR gates. Each gate is defined by its logic symbol and truth table. The AND gate outputs true only if all inputs are true. The OR gate outputs true if any input is true. NAND and NOR gates are composed of an AND or OR gate with a NOT gate added.

1. DIGITAL ELECTRONICS
Keywords:
Logic Gates, AND, OR, NOR, NAND
By :-KARAN JADHAV

2. Logic
Gates

3. 3
Logic Gates
• The building blocks used to create digital circuits
are logic gates
• There are three elementary logic gates and a
range of other simple gates
• Each gate has its own logic symbol which allows
complex functions to be represented by a logic
diagram
• The function of each gate can be represented by a
truth table or using Boolean notation

4. 4
• The AND gate
• The AND gate has the following symbol and truth table.
• Two or more input bits produce one output bit.
• Both inputs must be true (1) for the output to be true.
• Otherwise the output is false (0).

5. 5
• The OR gate
• The OR gate has the following symbol and truth
table.
• Two or more input bits produce one output bit.
• Either inputs must be true (1) for the output to
be true.

6. 6
• The NOT gate (or inverter)
• The simplest possible gate is called an "inverter" or a NOT
gate.
• One bit as input produces its opposite as output.
• The symbol for a NOT gate is shown below.
• The truth table for the NOT gate shows input and output.

7. 7What happens when you add a NOT
to an AND gate?
“Not AND” =
NAND
A B X
0 0 1
0 1 1
1 0 1
1 1 0

8. 8
• The NAND gate

9. 9What happens when you add a NOT
to an OR gate?
“Not OR” = NOR
A B X
0 0 1
0 1 0
1 0 0
1 1 0

10. 10
• The NOR gate

11. 11
• The Exclusive NOR gate
• The Symbol and Truth Table is shown below.
• Output will be high for same inputs