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1. DIGITAL ELECTRONICS
Paper Code:CBC1203
LOGIC GATES

2. CONTENT
 INTRODUCTION
 WHAT IS TRUTH TABLE
 TYPES OF LOGIC GATES WITH DIAGRAM
(1) AND gates
(2) OR gates
(3) XOR gates
(4) NOT gates
(5) NAND gates
(6) NOR gates
(7) XNOR gates.

3. INTRODUCTION
Logic gates are the electronic circuits in digital
system having one or more than one input and
only one output.
Logic gates perform logical operation that takes
binary inputs i.e., 0 and 1 and produce a single
binary output.

4. WHAT IS TRUTH TABLE
A truth table is a chart or a table which
shows all the possible combination of the
inputs and result it output.

5. Types of Basic Logic Gates
There are seven basic logic gates:
(1) AND gates
(2) OR gates
(3) XOR gates
(4) NOT gates
(5) NAND gates
(6) NOR gates
(7) XNOR gates.

6. AND GATES
• The output is "true" when both inputs are "true."
Otherwise, the output is "false.“
• In other words, the output is 1 only when both inputs
are 1.

7. Truth table
INPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
0
0
0
1

8. OR GATES
• The output is "true" if either or both of the inputs are
"true." If both inputs are "false," then the output is
"false."
• In other words, for the output to be 1, at least input one
OR two must be 1.

9. Truth table
INPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
0
1
1
1

10. XOR GATES
• The output is "true" if either, but not both, of the inputs are
"true."
• The output is "false" if both inputs are "false" or if both inputs
are "true.“
• Another way of looking at this circuit is to observe that the
output is 1 if the inputs are different, but 0 if the inputs are the
same.

11. Truth table
INPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
0
1
1
0

12. NOT GATES
• Not gate has only one input.
• If the input is 1, then the output is 0.
• If the input is 0, then the output is 1.

13. Truth table
INPUT OUTPUT
INPUT OUTPUT
1
0
0
1

14. NAND GATES
• The NAND is a combination of AND gate and
NOT gate.
• The output is "false" if both inputs are "true."
Otherwise, the output is "true."

15. Truth table
INPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
1
1
1
0

16. NOR GATES
• The NOR gate is a combination OR gate and
NOT gate.
• Its output is "true“ if both inputs are "false.“
Otherwise, the output is "false."

17. Truth table
INPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
1
0
0
0

18. XNOR GATES
• The XNOR (exclusive-NOR) gate is a combination of XOR
gate and not gate.
• Its output is "true" if the inputs are the same, and
"false“ if the inputs are different.

19. Truth table
INTPUT 1
INPUT 2
OUTPUT
INPUT 1 INPUT 2 OUTPUT
0
0
1
1
0
1
0
1
1
0
0
1

20. THANK YOU…