chapter 1 introduction: digital systems & logic design by taweesak reungpeerakul

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?

Continuous Values Digital Quantity?

Discrete Set of Values Which one has more advantages?

Digital Quantity (process & transmit) Efficiency Reliability

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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: 0 Low, 1 High

Code: Group of Bits

Logic Level: represented by voltages

Volts Volts(TTL)

VH (max)

VH (min)

VL (max)

VL (min)

Logic 1 (high)

Logic 0 (low)

Undefined

5.0

2.0

0.8

0.0

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Digital Waveforms Pulse

Positive-going pulse Negative-going pulse

Waveform Characteristic

Question

H

L

HL

90%

10%

50% tW

tr tfT

tW : pulse widthtr : rise timetf : fall timeT : periodf : frequency

f = 1/TT = 1/f

Duty Cycle = ( tw / T ) 100%

0 10 60 110

90%

10%

50% tW

tr tfT

Time(µs)

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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

NOT AND OR

Symbol

Truth Table

In Out0 11 0

In1 In2 Out

0 0 00 1 01 0 01 1 1

In1 In2 Out

0 0 00 1 11 0 11 1 1

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1.4 Basic Logic Functions

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Basic Logic Functions (cont) Mux Demux

S0

DS3

S2

S1

C0 C1 En

MultiplexerO0

DO3

O2

O1

C0 C1 En

Demultiplexer

n

2n

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Basic Logic Functions (cont)

Flip-flops

Counters

Registers

Q

QSET

CLR

DDCLK

CLR

SETQ

Q

CLKQ

QSET

CLR

D

Q

QSET

CLR

D

Q

QSET

CLR

D

Q

QSET

CLR

DD OUT

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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

BehavioralDescription

Concept

Behavioral Synthesis

RTL Description

Logic Synthesis

Mask Data

Floor Planning

Gate Description

Testing

Manufacturing

Layout

Technology Mapping

Technology Dependent Network

Good Product

Product