## 05 Apr Explain the basic differences between analog and digital technology. Explain the basic differences between the different numbering ?systems (binary, octal, hexadecimal, and decima

- Explain the basic differences between analog and digital technology.
- Explain the basic differences between the different numbering systems (binary, octal, hexadecimal, and decimal) presented in this unit.

EET 130– Digital Systems I

Digital Concepts

2

Outline of the lecture

Digital and Analog quantities

Binary Digits, logic levels and digital waveforms

Classification of Integrated Circuit( IC) Packages

Advantages and disadvantages of digital systems

Objective of the Lecture

After successful completion of the lecture students

will be able to: Name examples of analog and digital signals

Identify and define the differences between analog and digital signals

and their characteristics

Show how voltage levels are used to represent digital quantities

Identify typical digital signals & a timing diagram

Recognize the advantages and disadvantages of digital systems

Describe various parameters of pulse waveform

Introduction

Digital electronics is essential to understanding the

design and working of a wide range of applications

consumer and industrial electronics

Communications, embedded systems

Computers, security, military equipment

Integrated Circuits that operate on Digital Data are in

95% of every electrical powered device in the U.S

The job market for electronic designers and

technicians with Digital Design skills is at an all time

high and will continue growing

5

Analog and Digital Signals

The term “ signal will appear many times in

this course

It is anything which conveys information

It could be a voltage or current waveform from

electronic circuits

It could be one, two or three dimensional

Quantifying signals helps us to decide how

to store and transmit messages

Analog and Digital signals…

Signals are met in diverse fields of engineering

Elec. Eng. – voltages/currents in a circuit, speech signals,

image signals, video signals

Physics – radiation

Mech. Eng. – vibration studies

Astronomy – (2-D) pulsars, distant stars

Biomedicine – EEG, ECG, retinoscopy, MRI

Seismology – tectonic plate movement, earthquake

prediction

Economics – level of trading in stock market

Metrology – weather forecast, GPS

Analog and Digital Signals …

Examples of signals

Analog Signals and Digital Signals

Analog signals are signals in which the independent variable

is continuous

These signals are defined for a continuum of values of the

independent variable

They are continuous in value, in time, or both.

They are electrical signals whose values vary in analogy

with a physical quantity, e.g., temperature, force,

acceleration

Digital Signals are signals in which the independent variable

takes a discrete set of values

These signals are defined only at discrete times. Digital

signals are discrete in value, in time, or both.

Analog Signals

In analog representation a quantity is

represented by a voltage, current, or meter

movement that is proportional to the value of

that quantity

Analog quantities vary over a continuous

range of values

Digital Signals

In digital representation the quantities are

represented by discrete quantities (symbols)

called digits

Digital watch is the best example of digital

representation

Difference between analog and digital signal

ANALOG SIGNAL – continuous in value, in time, or both

It is an electrical signal whose value varies in an analogy with a physical quantity, e.g., temperature, force, acceleration

DIGITAL SIGNAL – discrete

in value, in time, or both

Analog signal- one whose output varies continuously in step with the input.

Example:

Analog

Digital signal- one whose output varies at discrete voltage levels commonly called HIGH or LOW (1 or 0).

Example:

Digital HIGH or 1

LOW or 0

Time

Difference between analog and digital signal

Difference between analog and digital signal

Difference between analog and digital signal

Analog signals could take any value at any given time

Digital signals take one of two values at any given time

Examples of Analog Signals

Sound: telephone, radio, CD

Examples of Digital Signals

• Serial transfer of data between computers

• Parallel transfer of data between computer & printer

Application of Analog and Digital Circuits

Public Address System

Is used to amplify sound so that it can be heard

by a large audience

It is a simple example of analog systems

Application of Analog and Digital Circuits…

Compact Disk Players

is an example of a system in which both digital and

analog circuits are used

Application of Analog and Digital Circuits…

Digital Watches: in our day to day activity we often see and

use these electronic devices

Application of Analog and Digital Circuits…

Robotics and control applications

digital circuits are widely applied in a wide range of applications

from the flight and propulsion systems of commercial airliners to

the cruise control present in many modern automobiles

Robotic systems could be applied in industries for different

applications where humans could not reach due to environmental

hazards and life hazards

Application of Analog and Digital Circuits…

Automation

digital systems are widely applied in process automation in industries

an automated tablet counting system for pharmaceutical industries is

shown in the next slide

22

23

Advantages and Disadvantages of Digital Systems

The most common advantages of digital systems over analog

systems are:

Easier to design – exact values of voltage or current are

not important, only the range (HIGH or LOW) in which

they fall.

Flexibility – a digital system can be reconfigured for some

other operations by simply changing the software program

and hardware change is not required

Accuracy- analog systems suffer from component

tolerance, breakdown etc, whereas accuracy in digital

systems is decided by the resolution of the A/D converter

and number of bits used to represent digital data.

24

Advantages and Disadvantages of Digital Systems

Easy storage- in digital systems storage is very easy and due to

which remote processing of digital signals is possible.

Mathematical Processing- complex mathematical algorithms

can be performed and implemented easily in digital systems

Cost- when there is large complexity in the application then

digital systems are cheaper compared to analog systems. In

digital systems the software algorithm may be complex but it

can be implemented accurately with less effort

Repeatability- Digital systems does not depend on strict

component tolerances and they can be duplicated easily

25

Advantages and Disadvantages of Digital Systems

Adaptability- digital systems are easily upgradable and they

can be reconfigured for other applications as they are software

controlled and no hardware change is required to adapt them

for other applications

Simplicity- some complex operations in analog systems can

be easily implemented using digital systems

Noise Immunity and security- digital systems have definite

and quantized levels and they are not corrupted by noise

Security systems such as encryption and scrambling can be easily done

in digital systems

Digital systems can be stored in magnetic tape and disks without

deterioration

Drawbacks of Digital Systems …

The real world is mainly analog

Most signals of practical interest are analog –

speech, image, video, sonar, radar etc…

To take advantage of digital techniques when dealing

with analog inputs and outputs, three steps must be

followed

Convert the real-world analog inputs to digital form (ADC)

Process (operate on) the digital information.

Convert the digital outputs back to real-world analog form.

(DAC)

Drawbacks of Digital Systems…

In a collective sense some of the drawbacks

of digital systems are: Digital techniques are limited to signals with relatively

low bandwidths. Currently digital systems are used for

signals up to video bandwidths (about 10 MHz)

The cost of high-speed ADCs and DACs and the amount

of digital circuitry required to implement very high-speed

designs (> 100 MHz) makes them impractical for many

applications.

The need for an ADC and DAC makes digital systems not

economical for simple applications (e.g., a simple filter)

Elements of digital systems

The figure below shows the most basic elements of digital

systems which allow the processing of analog signals

Reasons to the Shift to Digital Tech

Chief reasons for the shift to digital technology: Digital systems are generally easier to design.

Information storage is easy.

Accuracy and precision are easier to maintain throughout the

system.

Operations can be programmed.

Digital circuits are less affected by noise.

More digital circuitry can be fabricated on IC chips.

There have been remarkable recent advances in digital technology.

Advances will continue as digital technology expands and improves.

Binary Digits and Logic Levels

The two digits in the binary system, 1 and 0, are called bits

– a contraction of the words binary digit

In digital circuits two different voltage levels are used to

represent the two bits

Generally 1 is represented by the higher voltage, which we

will refer to as HIGH and a zero is represented by the

lower voltage level, which we will refer to as LOW –

Positive Logic

The reverse of the above notation where we represent 1

with LOW and 0 with HIGH is called Negative Logic

Logic Levels …

The voltages used to represent a 1 and a 0

are called logic levels

Ideally, one voltage level represents a

HIGH and another voltage level represents

a LOW

Type of logic Bit “1” Bit “0”

Positive Logic HIGH LOW

Negative Logic LOW HIGH

Logic Levels …

In practical digital circuits A HIGH can be any voltage between

a specified minimum value and a

specified maximum value

A LOW can be any voltage between

a specified minimum value and a

specified maximum

There is no overlap between the

accepted ranges of HIGH and LOW

levels

Logic Levels …

In digital systems there are two types of circuit

implementations:

TTL ( circuits made up of bipolar transistors)

CMOS ( circuits made up of MOSFET transistors)

In TTL circuits we adopt the following definitions for HIGH

and LOW levels.

LOW ≤ 15 % of the supply voltage ( VCC)

High ≥ 40 % of the supply voltage ( VCC)

For example, if the supply voltage is +5 volt then the logic

levels become

LOW ≤ 0.8 V and High ≥ 2 V

Logic Levels …

In CMOS circuits we adopt the following

definitions for HIGH and LOW levels.

LOW ≤ 30 % of the supply voltage (Vcc )

High ≥ 70 % of the supply voltage (Vcc)

For example, if the supply voltage is +5 volt

then the logic levels become

LOW ≤ 1.5 V, High ≥ 3.5 V

Logic levels …

The figure shows the defining levels of

HIGH and LOW for TTL and CMOS logic

Logic levels …

Binary values are represented by voltage levels

For ideal voltage levels as in the above figure has zero rise

time and fall time

This is not practically feasible

Components of Practical Digital Pulse

Major parts of a digital pulse

Base line

Amplitude

Rise time (tr)

Pulse width (tw)

Fall time (tf)

Digital Waveforms

tw = pulse width

T = period of the waveform

f = frequency of the waveform

The duty cycle of a binary waveform is defined as:

T

1 f

%100 T

t cycle Duty w

Integrated Circuits

An Integrated circuit (IC) is a number of logic

gates fabricated on a single silicon chip.

ICs can be classified according to how many

gates they contain as follows:

Small-Scale Integration (SSI): Contain 1 to 20 gates.

Medium-Scale Integration (MSI): Contain 20 to 200

gates. Examples: Registers, decoders, counters.

Large-Scale Integration (LSI): Contain 200 to 200,000

gates. Include small memories, some microprocessors,

programmable logic devices.

Very Large-Scale Integration (VLSI): Usually stated in

terms of number of transistors contained usually over

1,000,000. Includes most microprocessors and memories.

IC Packaging

IC packages are classified according to the

way they are mounted on the printed circuit

boards as

Through – hole mounted – example DIP

Surface mounted – example SOIC

SMT Package Examples

IC package styles

Dual in-line package (DIP) – through hole technology

Small-outline IC (SOIC) – surface mount technology

Fixed Function Integrated Circuits

Flat pack (FP)

Plastic-leaded chip carrier (PLCC)

Fixed Function Integrated Circuits

Leadless-ceramic chip carrier (LCCC)

Summary

Digital and Analog quantities

Binary Digits, logic levels and digital waveforms

Classification of Integrated Circuit( IC) Packages

Advantages and disadvantages of digital systems

Decimal Number System

Binary Number System

Decimal to Binary and Binary to Decimal Conversion

Binary Arithmetic

,

EET 130– Digital Systems I

Number Systems

2

Outline of the lecture

Decimal Number System

Binary Number System

Binary to decimal and Decimal to Binary conversions

Octal Number System

Hexadecimal Number system

1’s and 2’s complement of binary numbers

Signed numbers

Binary Coded Decimal ( BCD)

Digital Codes

Objective of the Lecture

After successful completion of the lecture students

will be able to: State the place values for decimal and binary number systems.

Convert decimal to binary and binary to decimal number system

Perform Binary Arithmetic Operations

State the place values for octal and hexadecimal number systems.

Convert octal to binary, octal to decimal, binary to octal and decimal

to octal number system

Convert hexadecimal to decimal, hexadecimal to binary, binary to

hexadecimal and decimal to hexadecimal

Determine 1’s and 2’s complement of a binary number

Express binary numbers in BCD form

Convert between binary system and Gray code

Interpret ASCII codes

Number Systems

Understanding digital systems requires an

understanding of the Number systems.

Many number systems are in use in digital

technology

The most common are the decimal, binary, octal,

and hexadecimal systems

The decimal system is clearly the most familiar to us

because it is a tool that we use every day

Most operations performed in decimal number

system are applied in other number systems too

Decimal Number System

The decimal system is composed of 10 numerals or symbols.

These 10 symbols are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; using these

symbols as digits of a number, we can express any quantity

The decimal system is also called the base-10 system

because it has 10 digits

The position of each digit in a decimal number indicates the

magnitude of the quantity represented and can be assigned a

weight:

… 105 104 103 102 101 100 . 10-1 10-2 10-3 10-4 10-5 …

Decimal Number System …

Example: Express the decimal number 47

as a sum of the values of each digit.

Solution:

The digit 4 has a weight of 10 (101), as indicated

by its position. The digit 7 has a weight of

1(100), as indicated by its position.

47 = (4 X 101) + (7 X 100)

= (4 X 10) + (7 X 1) = 40 + 7 Exercise: Determine the value of each digit in 939

Decimal Number System…

Example 2: Express the decimal number 568.25 as a sum

of the values of each digit.

Solution:

The whole number digit 5 has a weight of 100 (102), the

digit 6 has a weight of 10(101), the digit 8 has a weight

of 1(100)

the fractional digit 2 has a weight of 0.1 (10-1), and the

fractional digit 5 has a weight of 0.01 (10-2).

568.25 = (5 X 102) + (6 X 101) + (8 X 100) + (2 X 10-1) + (5 X 10-2)

= (5 X 100) + (6 X 10) + (8 X 1) + (2 X 0.1) + (5 X 0.01)

= 500 + 60 + 8 + 0.2 + 0.05

Exercise: Determine the value of each digit in 67.924

Binary Number System

In the binary system, there are only two symbols or possible

digit values, 0 and 1

This base-2 system can be used to represent any quantity that

can be represented in decimal or other number system

In a binary number system the number values are

determined by

The position of the digits multiplied by their positional weighting

Positive Powers of Two (whole numbers Negative Powers of Two (fractional numbers)

28 27 26 25 24 23 22 21 2 2-1 2-2 2-3 2-4 2-5 2-6

256 128 64 32 16 8 4 2 1 ½ 1/4 1/8 1/16 1/32 1/64

0.5 0.25 0.125 0.0625 0.03125 0.015625

Binary Counting

Binary to Decimal Conversion

Any binary number can be converted to its decimal equivalent

simply by

summing together the weights of the various positions in the binary

number which contain a 1

Example 1: Determine the decimal value of the binary whole

number 1101101

Solution:

Determine the weight of each bit that is a 1 and then find the

sum of the weights

Weight: 26 25 24 23 22 21 20

Binary number: 1 1 0 1 1 0 1

1101101 = 26 25 23 22 2 = 64 +32+ 8+ 4+ 1 = 109

Exercise: What is the decimal value of the binary number 10010001

Binary to Decimal Conversion …

Example 2: Determine the decimal value of

the fractional binary number 0.1011.

Solution:

First, determine the weight of each bit that is a 1,

and then sum the weights.

Weight: 2-1 2-2 2-3 2-4

Binary number: 0 . 1 0 1 1

0.1011 = 2-1 + 2-3 + 2-4 = 0.5 + 0.125 + 0.0625

= 0.6875

Exercise: Evaluate the binary number 10.111

Binary to Decimal Conversion …

The maximum value a binary number can have is

determined by the number of Binary digits or BITS present.

Therefore: Largest decimal number = 2n – 1

with five bits (n=5) the biggest decimal number that can be

represented is:

25 – 1 = 32 – 1 = 3110

To keep track of the digits in a binary numbering system

the Rightmost digit having the LOWEST weighting is

referred to as the Least Significant Bit, LSB

the Leftmost digit having the HIGHEST weighting is

referred to as the Most Significant Bit, MSB.

Decimal to Binary Conversion

Sum of weights method

Any decimal number can be converted to its

binary equivalent simply

Our website has a team of professional writers who can help you write any of your homework. They will write your papers from scratch. We also have a team of editors just to make sure all papers are of HIGH QUALITY & PLAGIARISM FREE. To make an Order you only need to click Ask A Question and we will direct you to our Order Page at WriteEdu. Then fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.

Fill in all the assignment paper details that are required in the order form with the standard information being the page count, deadline, academic level and type of paper. It is advisable to have this information at hand so that you can quickly fill in the necessary information needed in the form for the essay writer to be immediately assigned to your writing project. Make payment for the custom essay order to enable us to assign a suitable writer to your order. Payments are made through Paypal on a secured billing page. Finally, sit back and relax.

**Do you need help with this question?**

Get assignment help from WriteEdu.com Paper Writing Website and forget about your problems.

WriteEdu provides custom & cheap essay writing 100% original, plagiarism free essays, assignments & dissertations.

With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.

Chat with us today! We are always waiting to answer all your questions.