Page 25 - DCAP108_DIGITAL_CIRCUITS_AND_LOGIC_DESIGNS

Digital Circuits and Logic Design Nisha Sethi, Lovely Professional University

Notes Unit 2: Logic Gates

CONTENTS
Objectives
Introduction
2.1 Types of Logic Gates
2.1.1 The NOT (Inverter) Gate
2.1.2 The AND Gate
2.1.3 The OR Gate
2.1.4 NAND Gate
2.1.5 The NOR Gate
2.1.6 XOR Gate
2.1.7 XNOR Gate
2.1.8 Non-Inverter or Buffer
2.1.9 Open Collector and Open Drain
2.2 Tri-State Gates
2.2.1 Active “LOW” Tri-state Gate
2.2.2 Tri-state Gate Control
2.2.3 Double Inversion Using NOT Gates
2.2.4 Gate Fan-out Example
2.3 Summary
2.4 Keywords
2.5 Review Questions
2.6 Further Readings

Objectives

After studying this unit, you will be able to:
• Explain the types of logic gates
• Describe the circuit diagram of gates
• Discuss tri-state gates

Introduction

Logic gates are the basic components in digital electronics. They are used to create digital circuits
and even complex integrated circuits. For example, complex integrated circuits may bring already
a complete circuit ready to be used – microprocessors and microcontrollers are the best example
– but inside them they were projected using several logic gates. In this tutorial we will teach you
everything you need to know about logic gates, with several examples.
As you may already know, digital electronics accept only two numbers, “0” and “1”. Zero means
a 0 V voltage, while “1” means 5 V voltages or 3.3 V voltages on newer integrated circuits. You
can think “0” and “1” as a light bulb turned off or on or as a switch turned off or on.

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