1. Department of Electronics
LOGIC GATES BY
Prof J. John Wilson
Department of Electronics
St. Joseph’s College
Trichy

2. Outline The Inverter The AND Gate The OR Gate The NAND Gate
The NOR Gate
The Exclusive-OR
Exclusive-NOR Gates

3. The inverter
The inverter (NOT circuit) performs the operation called inversion or complementation.
The inverter changes one logic level to the opposite level.
In terms of bits, it changes a 1 to a 0 and a 0 to a 1.

4. Logic symbols

5. Truth Table When the input is LOW, the output is HIGH;
when the input is HIGH, the output is LOW,
thereby producing an inverted output pulse.

6. NOT Gate Operation with Waveform Inputs

7. Pin Diagram of NOT gate

8. The AND Gate
An AND gate can have two or more input and performs what is known as
logical multiplication.

9. Logic symbols

10. Operation of an AND Gate
For a 2-input AND gate, output X is HIGH only when inputs A and B are HIGH.
X is LOW when either A or B is LOW, or when both A and B are LOW.

11. Pin Diagram of AND Gate

12. Possible logic levels for a 2-input AND gate

13. Truth Table
Logic Expressions

14. AND Gate Operation with Waveform Inputs

15. Boolean expressions for AND gates

16. Application

17. Standard logic symbols for the OR gate

18. Operation of an OR Gate

19. Truth Table

20. PIN DIAGRAM

21. Timing Diagram

22. Boolean expressions for OR gates
Boolean addition is the same as the OR function

23. An Application

24. The NAND Gate

25. Operation of NAND Gate

26. Truth Table

27. Pin Diagram of NAND Gate IC

29. Application

30. The NOR Gate
The NOR gate can be used as a universal gate. NOR gates can be used in combination to perform the AND, OR, and inverter operations

31. Standard NOR gate logic symbols

32. Operation of NOR Gate

33. Truth Table

34. NOR Gate Operation with Waveform Inputs

36. Truth Table
Pin Diagram

37. An Application

38. The Exclusive-OR Gate

39. Operation of Exclusive –OR Gate

40. Truth Table

41. The Exclusive-NOR Gate

42. Truth Table

43. Exclusive-NOR Gate Operation with Waveform Inputs

44. THANK YOU