Digital Electronics - Lesson 6: Logic Gates PDF
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Uploaded by LavishEnlightenment3074
2021
Dr. Michael Angelo D. Ligayo
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Summary
This document is a lesson on digital electronics, focusing on logic gates. It explains binary representation and the functions of various logic gates like AND, OR, NAND, and NOR, including diagrams and truth tables. The document is likely used for educational purposes in a course on digital systems.
Full Transcript
DIGITAL ELECTRONICS LESSON 6: LOGIC GATES COMPILED BY: DR. MICHAEL ANGELO D. LIGAYO 09/22/2021 LOGIC GATES Digital Computers - Imply that the computer deals with digital information, i.e., it deals with the information tha...
DIGITAL ELECTRONICS LESSON 6: LOGIC GATES COMPILED BY: DR. MICHAEL ANGELO D. LIGAYO 09/22/2021 LOGIC GATES Digital Computers - Imply that the computer deals with digital information, i.e., it deals with the information that is represented by binary digits - Why BINARY ? instead of Decimal or other number system ? * Consider electronic signal 1 7 6 5 signal 4 3 range 2 1 0 0 binary octal 0 1 2 3 4 5 6 7 8 9 * Consider the calculation cost - Add 0 0 1 2 3 4 5 6 7 8 9 1 1 2 3 4 5 6 7 8 9 10 0 1 2 3 2 3 4 5 6 7 8 9 1011 3 4 5 6 7 8 9 101112 0 0 1 4 4 5 6 7 8 9 10111213 5 5 6 7 8 9 1011121314 1 1 10 6 6 7 8 9 101112131415 7 7 8 9 10111213141516 8 8 9 1011121314151617 9 9 101112131415161718 LOGIC GATES Binary Binary Digital Gate Digital. Output Input.. Signal Signal Types of Basic Logic Blocks - Combinational Logic Block Logic Blocks whose output logic value depends only on the input logic values - Sequential Logic Block Logic Blocks whose output logic value depends on the input values and the state (stored information) of the blocks Functions of Gates can be described by - Truth Table - Boolean Function - Karnaugh Map LOGIC GATES Name Symbol Function Truth Table A B X A X=A B 0 0 0 AND X or 0 1 0 1 0 0 B X = AB 1 1 1 A B X A 0 0 0 OR X X=A+B 0 1 1 1 0 1 B 1 1 1 A X I 0 1 A X X = A’ 1 0 A X 0 0 Buffer A X X=A 1 1 A B X A 0 0 1 NAND 0 1 1 X X = (AB)’ 1 0 1 B 1 1 0 A B X A 0 0 1 NOR X X = (A + B)’ 0 1 1 0 0 0 B 1 1 0 A B X A X=AB XOR X or 0 0 0 1 0 1 Exclusive OR 1 0 1 B X = A’B + AB’ 1 1 0 A B X A X = (A B)’ XNOR X or 0 0 0 1 1 0 Exclusive NOR B X = A’B’+ AB 1 0 0 or Equivalence 1 1 1 LOGIC GATES x y z F 0 0 0 0 Truth 0 0 1 1 Table 0 1 0 0 0 1 1 0 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 1 Boolean F = x + y’z Function x F Logic y Diagram z SOP or Sum-of-Products circuits LOGIC GATES Many different logic diagrams are possible for a given Function F = ABC + ABC’ + A’C.......…… (1) = AB(C + C’) + A’C..…. (2) = AB 1 + A’C = AB + A’C...…. (3) A B (1) C F A (2) B F C A B (3) F C Packaging of digital circuits Pin diagrams of TTL digital circuits
