DIGITAL ELECTRONICS- Logic Gates The AND gate The OR gate The NOT gate (or inverter) The NAND gate The NOR gate The Exclusive OR gate The Exclusive NOR gate

1. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
Affiliated Institution of G.G.S.IP.U, Delhi
DIGITAL ELECTRONICS
Paper Code :- BCA 106
Keywords:
Logic Gates, AND, OR, NOR, NAND
By :-HARI MOHAN JAIN

2. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
2
Logic
Gates

3. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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• 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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
8
• The NAND gate

9. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
10
• The NOR gate

11. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
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• The Exclusive OR gate
• Exclusive OR gate are true if either input is true but not both.
• The Symbol and Truth Table is shown below.
• Output will be high for different inputs

12. TRINITY INSTITUTE OF PROFESSIONAL STUDIES
Sector – 9, Dwarka Institutional Area, New Delhi-75
12
• The Exclusive NOR gate
• The Symbol and Truth Table is shown below.
• Output will be high for same inputs