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Chapter 1

Introduction: Digital Systems &

Logic Design

By Taweesak Reungpeerakul

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Digital Systems

� Digital and Analog Quantities

� Parameters of Pulse Waveform

� Basic Logic

� Combinational Logic

� Digital Integrated Circuits

� An example of Digital System

� Design Flow

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1.1 Digital & Analog Quantities

� Analog Quantity?

� Digital Quantity?

� Which one has more advantages?

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Analog & Digital Example

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Analog & Mixed System

� Analog System

� Digital and Analog System

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1.2 Binary Digits, Logic Levels, and Digital Waveforms

� Binary Digits:

� Code:

� Logic Level:

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Digital Waveforms

� Pulse

Positive-going pulse Negative-going pulse

� Waveform Characteristic

� Question

H

L

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Clock and Bits Waveforms

� Clock is a periodic waveform (signal) in which each interval

between pulse equals the time for one bit

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Timing Diagrams

� How 2 or more waveforms change and relate

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1.3 Basic Logic Operations

In1 In2 Out

0 0 1

0 1 1

1 0 1

1 1 0

In1 In2 Out

0 0 0

0 1 0

1 0 0

1 1 1

In Out

0 1

1 0

Truth Table

Symbol

ORANDNOT

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1.4 Basic Logic Functions

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Basic Logic Functions (cont)

� Demux

S0

D

S3S2S1

C0C1 En

MultiplexerO0

D

O3O2O1

C0C1 En

Demultiplexer

� Mux

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Basic Logic Functions (cont)

� Flip-flops

� Counters

� Registers

Q

QSET

CLR

DD

CLK

CLR

SETQ

Q

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1.5 Digital Integrated Circuits

� IC Packages: DIP, SMT, SOIC, PLCC, LCCC, FP

� IC Complexity Classifications

� SSI: gate ≥ 12, basic gates & flip-flops

� MSI: 12 ≤ gate ≥ 99, logic functions

� LSI: 100 ≤ gate ≥ 9999, including memory

� VLSI: 10,000 ≤ gate ≥ 99,999

� ULSI: gate ≥ 100,000

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Integrated Circuit Technologies

� Types of Transistors

� Bipolar Junction Transistors

� MOSFETs (metal-oxide semiconductor field-effect transistors)

� Bipolar used in: transistor-transistor logic (TTL) and emitter-couple logic (ECL)

� MOSFETs used in: complementary MOS

(CMOS) and n-channel MOS (NMOS)

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1.6 Testing and Troubleshooting Instruments

� Oscilloscope

� Analog

� Digital

� Logic Analyzer

� DC Power Supply

� Function Generator

� Digital Multimeter

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1.7 Digital System Application

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Design Flow