BRANCH-E&TC ENGINEERING

SEM – 3Rd

SUBJECT-DIGITAL ELECTRONICS

CHAPTER-01- BASIC OF DIGITAL ELECTRONICS

TOPIC- basic logic gates

Ay-2021-2022 ,winter-2021

FACULTY-ER S MOHANTA.(Hod e & tc engg Dept)

What are Logic Gates?

Description …

• Basic building blocks of a digital circuit
• Data processing on the circuit is controlled using transistors
• Output depends on the logic gate and the input
• Input is one of two states – high or low
• Output is one of two states – high or low
• There are seven types of logic gates

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What are Logic Gates?

There are three basic types of logic gate.

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• AND gate
• OR gate
• NOT gate

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The AND Gate

The AND Gate

The OR Gate

The OR Gate

The NOT Gate

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The logical inverter

The NOT Gate

Thinking in Binary

+

-

YES

TRUE

1

NO

FALSE

0

HIGH

LOW

True or False?

The AND Gate

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​

​

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TRUTH TABLE

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A

B

Q

0

0

0

0

1

0

1

0

1

1

1

0

True or False?

The OR Gate

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TRUTH TABLE

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A

B

Q

0

0

0

0

1

1

1

0

1

1

1

1

True or False?

The NOT Gate

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TRUTH TABLE

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A

Q

0

1

1

0

Combining Logic Gates

An AND gate and a NOT gate

A

B

C

Q

Combining Logic Gates

NAND gate

A

B

C

Q

Combining Logic Gates

An AND and

NOT Gate (NAND)

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TRUTH TABLE

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A

B

C

Q

0

0

0

0

1

0

1

0

0

1

1

1

1

1

1

0

Q = NOT (A AND B)