Chapter 1

INTRODUCTION

1

1.1 BACKGROUND:

India is the country in the world, in where the living population is between 20

to 45 years means population comprise more youngsters in comparison with other

countries in the world. Many of them have precious skills. We hope that research

will help to stimulate young Indians and ignite their minds. There are several

sectors of research and to get the successes in it among them electronics is also one

branch. With the help of which, we can get the more creative knowledge which can

be helpful for the welfare of the human being. Now a day’s it is a question in front

of us, day to day we get the new electronics products which serves the human being

very successes fully. Today’s new product after few seconds / minutes / hours /

maximum day becomes old. How it is possible? It is possible due to the computer

and various spice software’s. but our number of youngsters those who are well

known about the electronics and computer also but they did not know the

information about the SPICE that’s why they spends their valuable time for to built

very small circuits in electronics. This work provides information about the

different spice software’s which plays an important role in the revolution of

electronics. For to get the clear idea about it I like to start my work from the

information of an electron.

1.2 ELECTRON:

The discovery of electron can be considered as the starting point of the

development of modern physics. The study of motion of electron and other related

phenomenon has given rise to new exciting branches of physics such as atomic

physics, nuclear physics, solid state physics etc. the study has brought about

revolutionary changes in our concepts regarding the structure of matter and nature

of energy.

“Electron is a very small invisible quantity of electricity present in all

materials” [1].

2

“Electron is a stable subatomic particle with a charge of negative electricity,

found in all atoms and acting as a primary carrier of electricity in solids (atoms)”

[2].

According to modern theory the matter is electrical in nature. All the materials

are composed of very small partials called atoms. The atoms are the building bricks

of all matter. An atom consists of a central nucleus of positive charge around which,

negatively charged particles, called electrons revolve in different orbits [3].

During the investigation of discharge of electricity through gases at low

pressures, cathode rays were discovered, there properties were studied and it was

found that cathode rays are negatively charged partials. In 1897, Sir J. J. Thomson

determined the velocity and ratio of charge to mass (e / m) of these particles by

using a discharge tube. Thomson repeated the experiment, using different gases in

the discharge tube and cathodes of different materials. He found that the e / m ratio

is always constant, irrespective of the material of the cathode or the nature of the

gas. He therefore concluded that these particles are the constituents of atoms of all

substances. These particles were subsequently named as ‘electron’. Some

magnitudes and measurements about an electron are.

Charge on electron e = 1.602 x 10-19

Mass of an electron m = 9.0 x10

Coulomb.

-31

Radius of an electron r = 1.9 x 10

Kilogram.

-15

e / m ratio of an electron = 1.7589 x 10

meter.

11

This means the mass of an electron is very small as compared to its charge. It

is due to a property of an electron that it is very mobile and is greatly influenced by

electric or magnetic field. An electron moves round the nucleus posses two types of

energies viz. kinetic energy due to its motion and potential energy due to the charge

on nucleus. Its total energy is equal to its sum of kinetic and potential energy. The

electron in innermost orbit posses less energy in comparison with outermost orbit.

coulomb / kg

1. The electrons in the outermost orbit of an atom are known as valance

electrons. The valance electrons which are very loosely attached to the nucleus are

3

known as free electrons move towards the positive terminals of the supply,

constituting electric current.

2. An insulator is a substance which has practically no free electron at ordinary

temperature. Therefore an insulator does not conduct current under the influence of

potential difference.

3. A semiconductor is a substance which has very few free electrons at room

temperature. Consequently, under the influence of potential difference, a

semiconductor practically conducts no current [4].

The liberation of electron from the surface of a substance is known as

electron emission. The amount of additional energy required to emit an electron

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Types of electron emission:

) of that metal. It is different

for different substances.

Thermionic emission: It is observed in the metals due to the heat electrons are

emitted. The number of emitted electron is proportional to applied temperature.

Field emission: It is observed in metals due to application of high positive potential

electrons are emitted. The number of emitted electron is proportional to applied

potential.

Photo-electric emission: Due to the energy of light incident on the surface of the

metal electrons are emitted. The number of emitted electron is proportional to

intensity of light incident on surface.

Secondary emission: Due to high velocity beam of electrons which strike the metal

surface causes the emission of electrons [5].

1.3 VACUUM TUBES:

The vacuum tubes have been described as the most important single piece

device during the twelfth century. Its development has produced new branch of

science called electronics. The applications of vacuum tubes are so varied that this

“miracle tool” has owned a place in the industrial and commercial fields. These

4

tubes have been finding wide applications in radio, long distance telephones, sound

motion pictures, television, radar, computer and in industrial automation also.

“An electronic device in which the flow of electron through vacuum is known

as vacuum tube”

In vacuum tubes there are two principal electrodes called cathode and anode.

Cathode: after heating the filament it emits the electrons due to the thermionic

emission. Anode: it is also called plate; it collects the electrons emitted from

cathode when a positive potential is applied. The other electrodes in vacuum tubes

are called grids. Control grid: is used to control the flow of electrons between

cathode and anode. Screen grid: is generally held at some constant potential and

serves to alter the characteristics of the vacuum tube.

In 1904 Sir J. A. Fleming an English Physicist, invented first vacuum tube

(diode valve), called the Fleming valve. In vacuum tubes cathode is at the centre.

There is a filament for heating the cathode. The cathode is in the form of nickel

cylinder coated with barium and strontium oxides and is heated indirectly to provide

electron emission. The anode is a hollow cylinder made of nickel or molybdenum

adjusted co-axially outside the cathode. Screen grid (gs1) is made from the wire

mesh and is placed between grid (g) and plate p. screen grid is operated at fixed

positive potential w. r. t. cathode but somewhat lower than the plate voltage. In

order to eliminate the undesirable effects of secondary emission an additional grid

called suppressor grid is inserted between the plate and the screen grid (gs1). The

suppressor grid is connected to the cathode and serves to suppress the effects of the

secondary emission. These components are enclosed in a highly evacuated glass

tube.

The device which contains only cathode and plate is called diode, when control

grid is added to there, it is called triode, if suppressor grid is added it is called

tetrode etc. Vacuum tubes are classified according to number of electrodes in them.

5

Table 1.1 Different parameters of vacuum tubes.

Sr.

No.Parameter Triode Tetrode Pentode

1 Amplification factor (µ)

10 to 100 2 Range around 500 2

1000 2$&"$ 5000 2

2 Plate resistance (rp

300 k2$&"$3444$-$2 )

70 to 1000 k2$ 0.5 to 2 M2$

3 Tran conductance (gm

About 2500 µ mho )

About 1000 µ mho About 1000 to 90 µmho

The vacuum tubes discussed so far shall give satisfactory performance in a

circuit if they are operated under proper conditions.

Causes of tube failure:

Filament failure: filament wires gradually loose molecules they get weakened at

same point and therefore burnt out.

Tube becomes gassy: If the envelop leaks air is drawn in to the tube. The

internal elements give off gas when over heated by excessive currents.

Loose elements: When elements are not welded properly, they vibrate, causing

open or short circuits in the tubes.

As the filament in the vacuum diode heated to a high temperature, there is loss

of energy in the form of heat.

Vacuum tubes need a high voltage to be applied to its plates.

Vacuum tubes require more space and heavy in weight.

Vacuum tubes action is not instantaneous.

Vacuum tubes are more costly.

The vacuum tubes have been replaced by semiconductor devices; but these tubes

are still used at many places in special electronic circuits [4].

1.4 SEMICONDUCTOR:

A solid substance that is a non conductor when pure or at a low temperature but

has conductivity between that of insulators and metals. When containing a suitable

6

impurity or at higher temperature [2]. “The substances which has resistivity (10-4

to

0.5 2$#5$ (.$ 6'&/''.$ ,".7+,&"!*$ %.7$ (.*+)%&"!*$ (*$ ,%))'7$ *'#(,".7+,&"!89$ :;<$ '8=8

Germanium, Silicon, Selenium, Carbon etc. (The elements in the fourth group of

periodic table are neither good conductor nor bad conductor of electricity). It has

been seen that the crystal structure and the bonding of atoms of these elements are

responsible for the electrical conductivity of these elements; there are two types of

semiconductors called intrinsic and extrinsic semiconductors.

Table 1.2 Comparison between Intrinsic semiconductor Extrinsic

semiconductor.

Intrinsic semiconductor Extrinsic semiconductor

“Pure semiconductors are called intrinsic semiconductors.”!

“A semiconductor obtained by doping is called extrinsic semiconductor.”!

The electrical conduction in the intrinsic semiconductor is due to the thermally generated charge carriers. !

Doping – Is a process in which small number of suitable replacement atoms called impurities are introduced in the crystal.!

The densities of electrons and that of holes are equal in intrinsic semiconductor.!

Typically about one atom in 107 silicon atoms is replaced by dopant atoms

It is difficult to produce intrinsic semiconductor because of the difficulty in preparing extremely pure material.!

Generally Vth A group & IIIrd A group elements are doped as impurity.!

N- Type semiconductor:

When Vth A group elements like Arsenic (As), Antimony (Sb), phosphorous (P)

are doped in a crystal of silicon or germanium atom the covalent bond is formed

between all adjacent atoms by using four of the outer shell electrons and one

electron is left over.

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This electron associated with Arsenic atom has energy equal to that of free

electron. A small amount of thermal energy detaches this electron from the

Arsenic and the electron becomes free in the lattice.

The pentavalent impurity which Donets electron is called donor impurities is

called n-type semiconductor.

The majority charge carriers are electrons.

P- Type semiconductor:

When IIIrd A group elements like Aluminum (Al), Indium (In) etc. are doped in a

crystal of silicon or germanium the IIIrd

One bond is incomplete because of the deficiency of one electron .this electron

vacancy appears as a hole

A group atoms replaces a silicon or

germanium atom. Three valance electrons of Indium take part in forming the

covalent bonds with the adjacent atoms

By acquiring thermal energy electron from the neighboring bond can fill this site

having hole in another place. This migration of the hole gives rise to electrical

conduction.

The trivalent impurity acts as an acceptor for electron. Hence trivalent impurity is

called acceptor. The doped semiconductor with such impurity is called p-type

semiconductor.

The majority charge carriers in p-type semiconductors are called holes.

1.5 DIODE:

When a p-type semiconductor is suitably joined to n-type semiconductor, the

contact surface is called pn-juncation.

The region where free electron & free holes are absent is called Depletion

region. A PN - Junction Acts As A Diode. The p-regions referred as anode and the

n-region is reared to as cathode. A schematic diagram of junction diode and it

symbol is shown in following fig.

8

The potential difference across a pn-junction can be applied in two ways

namely.

A.Forward biasing:

When external voltage applied to the junction is in such a direction that it

cancels the potential barrier, thus [emitting current flow it .is called forward

biasing. The potential barrier is reduced and at some forward voltage (0.1V to

0.3V), it is eliminated together. Junction offers low resistance (Rf) to current flow.

Current flows in the circuit due to the establishment of low resistance path. The

magnitude of current depends upon the applied forward voltage.

B. Reverse biasing:

When the external voltage applied to junction in such a direction that

potential barrier is increased, it is called reverse biasing. In this case the potential

barrier is increased. The junction offers very high resistance called reverse

resistance (Rr) to current flow. Now the current flows in a circuit due to the

establishment of high resistance in the path.

From the above discussion it follows that with reverse bias to the junction, a

high resistance path is established and hence no current flows. On the other hand

with forward bias the junction a low resistance path is set up and hence current

flows in the circuit.

C. Break down voltage:

It is the minimum reverse voltage at which PN-junction breaks down with

sudden rise in reverse current.

D. Knee voltage:

It is the forward voltage at which the current through the junction starts to

increase rapidly.

For silicon diode knee voltage is - 0.7 V.

For germanium diode knee voltage is - 0.3V.

The diode conducts in forward bias & it does not conduct in reverse bias. This

unilateral conduction characteristic of PN-junction is similar to that of vacuum

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diode. Therefore like a vacuum diode a semiconductor diode can also accomplish

the job of rectification that is to change alternating current to direct current.

However semiconductor diodes are more popular as they are smaller in size,

cheaper, robust and usually operate with greater efficiency.

Rectification is not all that diode can do. A number of specific types of diodes

are manufactured for the specific applications. Some of the common purpose diodes

are:

1.5.1 Zener diode:

The Zener diode operated in the reverse break down region, will have a

relatively constant voltage across it. This permits the Zener diode to be used as a

voltage regulator.

1.5.2 Light emitting diode (led):

It is a diode that gives of visible light when forward biased. These are

available in various colors in the market. The LED is a solid-state source of light.

LEDs have replaced incandescent lamps in many applications because they have

number of advantages. These operate at low voltage. Have longer life i.e. more than

20 years and have fast on of switching.

1.5.3 Photo diode:

Is a reversed biased silicon or germanium PN-junction in which reverse

current increases when the junction is exposed to light. A photo diode differs from a

rectifier diode in that when its PN-junction is exposed to light, the reverse current is

increases with the increase in the light intensity and vice-versa. An opt isolator (also

called opt coupler) is a device that uses light to couple a signal from its input (a

photo-emitter e.g. A LED) to its output (a photo-detector e.g. A photo-diode).

1.5.4 Tunnel diode:

Is a PN-Junction that exhibits negative resistance between two values of

forward voltage (i.e. between peak-point voltage & valley -point voltage). In a

tunnel diode depletion layer is very narrow, in comparison with conventional diode.

The depletion layer of tunnel diodes is 100 times narrower compared to LED. The

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operation of a tunnel diode depends upon the tunneling effect & hence the name. “

The movements of the valence electrons from the valance energy band to

conduction band with little or no applied forward voltage is called tuning effect .”

Valance electron seen to tunnel through the forbidden energy gap.

1.5.5 Varactor diode:

A junction diode which acts as a variable capacitor under changing reverse bias

is known as a varactor diode.

CT

Where C

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T =

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Total capacitance of the junction.

A = Cross-sectional area of the junction.

Wd = Width of the depletion layer.

CT can be changed simply by changing the voltage VR

for this reason a

Varactor diode is sometimes called voltage controlled capacitor. Varactor diode is

always operated with reverse bias.

1.5.6 Shockley diode:

Shockley diode is equivalent to three junction diodes connected in series.

Shockley diode behaves like a switch so long as the forward voltage is less than the

break over voltage. Shockley diodes offer very high resistance (i.e. switch is open)

and practically conducts no current. at voltages above the break over value,

Shockley diode presents a very low resistance (i.e. switch is closed) and Shockley

diode conducts heavily. It may be noted that Shockley diode is also known as

PNPN diode or four layer diode or reverse- blocking diode thyristor.

11

Diode Zener diode Light emitting diode

Photo diode Varactor diode Shockley diode

Figure 1.1 Symbols of different types of diodes.

1.6 TRANSISTORS:

When a third doped element is added to a crystal diode in such a way that two

p-n-junctions are formed. The resulting device is known as transistor. The transistor

is entirely new type of electronic device is capable of achieving amplification of

weak signals in a fashion comparable and often superior to that realized by vacuum

tube. Transistors are far smaller than vacuum tube. They are mechanically strong

have practically unlimited life and can do some more jobs better than vacuum tubes.

Invented in 1948 by J. Bardeen and W. H. Brattain of Bell, Telephone,

Laboratories, U. S. A. transistor has now becomes a heart of most electronic

applications. Though transistor is only slightly more than 61 years old, yet it is fast

replacing vacuum tubes. In almost all the applications “Transistor consists of two

PN-junctions formed by sandwiching either p-type or n-type semiconductor

between a pair of opposite types.”

Figure 1.2 Symbols of NPN transistor and NPN transistor

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A transistor has three sections of doped semiconductors. The section on one

side is Emitter; the section the opposite side is the Collector, the middle section is

called Base and forms two junctions between the emitter and collector.

A. Emitter: The section on the one side that supplies charge carriers (electrons or

holes) is called the emitter. It is heavily doped so that it can inject a large number of

charge carriers. The emitter is always forward biased with respect to base so that it

can supply the large number of majority carriers.

B. Collector: The section on the other side that collects the charges is called the

collector. The collector is always reverse biased with respect to base. Its function is

to remove charges from its junction to the base.

C. Base: Middle section which forms two PN- junctions between the emitter and

collector is called the base. The base is lightly doped and very thin; it posses most

of the emitter injected charge carriers to the collector. The base emitter junction is

forward biased, allowing low resistance for the emitter circuit. The base collector

junction is reverse biased and provides high resistance to the collector circuit. The

transistor is connected in the circuit in the following three ways.

Common base connection.

Common emitter connection.

Common collector connection.

Each circuit connections has its specific advantages and disadvantages. The

comparison of transistor connections is shown in following chart.

13

Table 1.3 shows characteristics of different amplifiers.

Sr.

No.Characteristics Common Base

Common

Emitter

Common

Collector

1. Input Resistance

Low about 100 2 Low about 750 2

Very high about 750 k2

2. Output Resistance

Very high 450 k2 High about 45 k2

Low about 50 2

3. Voltage Gain About 150 About 500 Less than 1

4. Amplifications For high frequency application

For audio frequency

For impedance matching

The basic function of transistor is to do amplification the weak signal is given

to the base of the transistor and amplified output is obtained in the collector circuit.

One important requirement during amplification is that only the magnitude of the

signal should increase and no change in signal shape. This increase in magnitude of

the signal without any change in shape is known as faithful amplification.

For achieving faithful amplification, the following basic conditions must be

satisfied. Proper zero signal collector current.

Maximum proper base-emitter voltage (VBE) at any instant.

Maximum proper collector-emitter voltage (VCE) at any instant.

D. How transistor amplifies:

Following fig shows a single stage transistor amplifier. When a weak AC signal

is given to a base of transistor, a small base current (which is AC) starts flows

through the collector load Rc. As the value of Rc is quite high (usually 4 to 10 k25$

therefore large voltage appears a amplitude form in the collector circuit. It is in this

way that the transistor acts as an amplifier.

The action of transistor amplifier can be beautifully explained by referring the

fig. 5.2. Suppose a change of 0.1 Volt is applied to the base will give an output

voltage as = 2 mA x 5 k2$>$34$D")&8

14

Thus the transistor has given rise to a voltage 0.1 volt to 10 volt i.e. voltage

amplification / stage gain as 100. The phase difference of 180o

E. Multistage transistor amplifier:

between the signal

voltage and output voltage in a common emitter amplifier is known as phase

reversal.

Sometimes output from a single stage amplifier usually insufficient to derive an

output device. In other words the gain of a signal amplifier is inadequate for

practical purpose. Consequently additional amplification over two or three stages

can be achieved by a cascade process the output of the either stage, is given as a

input to next stage. The resulting system is called a multistage or cascade amplifier.

It may be emphasized here that a cascade amplifier is always a multistage amplifier.

In a transistor radio receiver sets the number of amplification stages may be six or

more.

Sometimes two stages of the amplifier stages are coupled either by a

resistance, capacitance and transistor or by direct wire.

Table 1.4 Comparison of different types of coupling.

Sr.

No. Particular RC CouplingTransformer

CouplingDirect coupling

1.Frequency response

Excellent in the audio frequency range

Poor Best

2. Cost Less More Least

3.Space & Weight

Less More Least

4.Impedance matching

Not good Excellent Good

5. Use For Voltage amplification

For power amplification

For amplifying extremely low

frequencies

1. The electron tube is a voltage driven device. Transistor is current operated

device.

15

2. The input and output impedances of a electron tubes are generally very large.

The input and output impedances of a transistor are relatively small.

3. Tube amplifier requires much voltage. The voltage for transistor amplifier is

very small.

4. The resistance of the components of the transistor amplifier is generally smaller

than the resistances of corresponding components of the tube amplifier.

5. The capacitance of the component of the transistor amplifier is usually larger

than the corresponding components of the tube amplifier.

6. Tube amplifiers are cost effective; require more space while transistor

amplifiers have low cost.

7. Tube amplifiers have less life while transistor amplifier has more life.

“A transistor amplifier which raises the power level of the signals that have

audio frequency range is known as transistor audio amplifier” [6-7].

Table 1.5 Particulars for voltage and power amplifier.

Sr.

No.Particular Voltage amplifier Power amplifier

1 E$0=%(.5 High ( > 100 ) Low ( 2 to 20 )

2 Rc High ( 4 to 10 k2$5 Low ( 5 to 20 2$5

3 Coupling Usually R-C coupling

Invariably transformer coupling.

4 Collector voltage

Low a few ( mV ) High ( 2 to 4 V )

5 Collector current

Low ( F$3$#G$5 High ( > 100 mA )

6 Power output Low High

7 Output impedance

Low ( F$3H$-2$5 (2002$5

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1.7 INTEGRATED CIRCUIT:

An electronic circuit or integrated circuit (also known as IC, microcircuit,

microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting

mainly of semiconductor devices as well as) passive: components that have been

manufactured in the surface of a thin substrate of semiconductor material.

Integrated circuits are used in almost all electronic equipment in use today and have

revolutionized the world of electronics.

A hybrid integrated circuit is a miniaturized electronic circuit constructed of

individual semiconductor devices, as well as passive components, bonded to a

substrate or circuit board.

1.7.1 Introduction:

Synthetic detail of an integrated circuit: it is a four layer of planarizeds copper

interconnect, down to the polysilicon (pink), wells (grayish), and substrate (green).

Integrated circuits were designed which are semiconductor devices and could

perform the functions of vacuum tubes, in the mid-20th-century, because of

technology advancements in semiconductor device fabrication.

The integration of large numbers of tiny transistors into a small chip was an

enormous improvement over the manual assembly of circuits using discrete

electronic component. The integrated circuits mass production capability,

reliability, and building-block approach to circuit design ensured the rapid adoption

of standardized ICs in place of designs of using discrete transistors.

There are two main advantages of ICs over discrete circuits: cost and

performance. Cost is low because the chips, with all their components, are printed

as a unit by photolithography and need not be constructed using one transistor at a

time. Further, much less material is used to construct a circuit in an IC die compress

to a discrete circuit. Performance is high since the components switch quickly and

consume little power (compared to their discrete counterparts) because the

components are small and close together. Today’s chips areas have which range

17

from few square millimeters to around 350 mm2, having 1 million transistors per

mm2

1.7.2 Invention:

.

The idea of an integrated circuit was conceived by a radar scientist working for

the Royal Radar Establishment of the British Ministry of Defense Geoffrey W. A.

Dummer (1909-2002), who first published it at the Symposium on Progress in

Quality Electronic Components in Washinton D.C. on May 7, 1952. [7] He gave

many symposia publicly to propagate his ideas. Dummer unsuccessfully attempted

to build such a circuit in 1956.The integrated circuit can be credited as being

invented by both Jack Kilby of Texas Instruments [8] and Robert Noyce of

Fairchild Semiconductor [9] working independently unaware of each other. Kilby

recorded his initial ideas concerning the integrated circuit in July 1958 and

successfully demonstrated the first working integrated circuit on September 12,

1958 [8] Kilby won the 2000 Nobel Prize in Physics for his part of the invention of

the integrated circuit. [10] Robert Noyce also came up with an idea of integrated

circuit, half a year later than Kilby. Noyce's chip had solved many practical

problems which could not be solved by a microchip developed by Kilby. Noyce's

chip, made at Fairchild, was made up of silicon, whereas Kilby's chip was made of

germanium.

Early developments of the integrated circuits trce back to 1949, when the

German engineer Werner Jacobi (Siemens AG) filed a patent for an integrated-

circuit-like semiconductor amplifying device [11] showing five transistors on a

common substrate arranged in a 2-stage amplifier arrangement. Jacobi devised a

small cheap used in hearing aids as typical industrial applications of his patent. A

commercial use of his patent has not been reported.

As a precursor, to the IC, was to create small ceramic squares (wafers), each

one containing a single miniaturized component which could then be integrated and

wired into a bidimensional or tridimensional compact grid. This idea, which looked

very promising in 1957, was proposed to the US Army by Jack Kilby, and led to the

18

short-lived Micromodule Program (similar to 1951's Project Tinkertoy) [12]

However, as the project was gaining momentum, Kilby came up with a new,

revolutionary design: the IC.

The aforementioned Noyce credited Kurt Lehovec of Sprague Electric for the

principle of p-n junction isolation caused by the action of a biased p-n junction (the

diode) as a key concept behind the IC [13].

1.7.3 Generations: SSI, MSI AND LSI:

The first integrated circuits contained only few transistors named as "Small-

Scale Integration" (SSI), digital circuits containing transistors numbering in the tens

provided a few logic gates for example, while early linear ICs such as the Plessey

SL201 or the Philips TAA320 had as few as two transistors. SSI circuits were

crucial to early aerospace projects, and vice-versa. Both the Minuteman Missile and

Apollo program needed lightweight digital computers for their inertial guidance

systems; the Apollo guidance computer led and motivated the integrated-circuit

technology, while the Minuteman missile forced it into mass-production.

These programs purchased almost all of the available integrated circuits from

1960 through 1963, and almost alone provided the demand that funded the

production improvements to get the production costs from $1000/circuit (in 1960)

to merely $25/circuit (in 1963). They began to appear in consumer products at the

turn of the decade, a typical application being FM inter-carrier sound processing in

television receivers.

The next step in the development of integrated circuits, taken in the late 1960s,

introduced devices which contained hundreds of transistors on each chip, called

"Medium-Scale Integration" (MSI).

They were attractive economically because while they cost little more to

produce than SSI devices, they allowed more complex systems to be produced

using smaller circuit boards, less assembly work (because of fewer separate

components), and a number of other advantages.

19

Further development, driven by the same economic factors, led to "Large-Scale

Integration" (LSI) in the mid 1970s, with tens of thousands of transistors per chip.

Integrated circuits such as 1K-bit RAMs, calculator chips, and the first

microprocessors, that began to be manufactured in moderate quantities in the early

1970s, had under 4000 transistors. True LSI circuits, approaching 10000 transistors,

began to be produced around 1974, for computer main memories and second-

generation microprocessors.

1.7.4 VLSI:

The final step in the development process, starting in the 1980s and continuing

through the present, was "very large-scale integration" (VLSI). The development

started with hundreds of thousands of transistors in the early 1980s, and continues

beyond several billion transistors as of 2007.

There was no single breakthrough that allowed this increase in complexity,

though many factors helped. Manufacturing moved to smaller rules and cleaner

fabs, allowing them to produce chips with more transistors with adequate yield, as

summarized by the International Technology Roadmap for Semiconductors (ITRS).

Design tools improved enough to make it practical to finish these designs in a

reasonable time. The more energy efficient CMOS replaced NMOS and PMOS,

avoiding a prohibitive increase in power consumption. Better texts such as the

landmark textbook by Mead and Conway helped schools educate more designers,

among other factors.

In 1986 the first one megabit RAM chips were introduced, which contained

more than one million transistors. Microprocessor chips passed the million

transistor mark in 1989 and the billion transistor mark in 2005[14]. The trend

continues largely unabated, with chips introduced in 2007 containing tens of

billions of memory transistors [15].

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1.7.5 ULSI, WSI, SOC & 3D-IC:

To reflect further growth of the complexity, the term ULSI that stands for

"Ultra-Large Scale Integration" was proposed for chips of complexity of more than

1 million transistors.

Wafer-scale integration (WSI) is a system of building very-large integrated

circuits that uses an entire silicon wafer to produce a single "super-chip". Through a

combination of large size and reduced packaging, WSI could lead to dramatically

reduced costs for some systems, notably massively parallel supercomputers. The

name is taken from the term Very-Large-Scale Integration, the current state of the

art when WSI was being developed.

System-on-a-Chip (SOC) is an integrated circuit in which all the components

needed for a computer or other system is included on a single chip. The design of

such a device can be complex and costly, and building disparate components on a

single piece of silicon may compromise the efficiency of some elements. However,

these drawbacks are offset by lower manufacturing and assembly costs and by a

greatly reduced power budget: because signals among the components are kept on-

die, much less power is required (see Packaging, above) to run them.

Three Dimensional Integrated Circuit (3D-IC) has two or more layers of active

electronic components that are integrated both vertically and horizontally into a

single circuit. Communication between layers uses on-die signaling, so power

consumption is much lower than in equivalent separate circuits. Judicious use of

short vertical wires can substantially reduce overall wire length for faster operation.

1.7.6 Advances in integrated circuits:

Among the most advanced integrated circuits is the microprocessor or "cores",

which control everything from computers to cellular phones to digital microwave

ovens. Digital memory chips and ASICs are examples of other families of

integrated circuits that are important to the modern information society. While the

cost of designing and developing a complex integrated circuit is quite high, when

spread across typically millions of production units the cost of individual IC is

21

minimized. The performance of ICs is high because the small size allows short

traces which in turn allows low power logic (such as CMOS) to be used at fast

switching speeds.

ICs have consistently migrated to smaller feature sizes over the years, allowing

more circuitry to be packed on each chip. This increased capacity per unit area

decreases cost and increase in functionality. See Moore’s law which, states that,

“the number of transistors in an integrated circuit doubles every two years”. In

general, as the feature size shrinks, almost everything improves. The cost per unit

and the switching power consumption also goes down, and the speed goes up.

However, ICs with nanometer-scale devices are not without their problems,

principal amongst them is leakage current (see sub threshold leakage for a

discussion on this). Although these problems are not insurmountable, will likely be

solved or at least ameliorated by the introduction of high-k dielectrics. Since speed

and power consumption gains are apparent to the end user, there is fierce

competition among the manufacturers to use finer geometries. This process, and the

expected progress over the next few years, is well described by the International

Technology Roadmap for Semiconductor (ITRS).

1.7.7 Popularity of ICs:

Only a half century after development of ICs or transistors was initiated,

integrated circuits have become ubiquitous. Computer, cellular phones, and other

digital appliances are now inextricable parts of the structure of modern societies.

That is, modern computing, communications, manufacturing, and transport systems,

including the Internet, all depend on the existence of integrated circuits. Indeed,

many scholars believe that the digital revolution brought about by the microchip

revolution was one of the most significant occurrences in the history of mankind.

1.7.8 Classification:

Integrated circuits can be classified into analog, digital and mixed signal (both

analog and digital on the same chip).

22

Digital integrated circuits can contain anything from one to millions of logic

gates, flip-flops, multiplexers and other circuits in a few square millimeters. The

small size of these circuits allows high speed, low power dissipation, and reduced

manufacturing cost compared with board-level integration. These digital ICs,

typically microprocessors, DSPs, and micro controllers work using binary

mathematics to process "one" (on) and "zero" (off) signals.

Analog ICs, such as sensors, power management circuits, and operational

amplifiers, work by processing continuous signals. They perform functions like

amplification, active filtering, demodulation, mixing etc. Analog ICs ease the

burden on circuit designers by having expertly designed analog circuits available

instead of designing a difficult analog circuit from scratch.

ICs can also combine analog and digital circuits on a single chip to create

functions such as A/D converters and D/A converters. Such circuits offer smaller

size and lower cost, but must carefully account for signal interference.

1.7.9 Fabrication:

Rendering of a small standard cell with three metal layers (dielectric has been

removed). The sand-colored structures are metal interconnect, with the vertical

pillars being contacts, typically plugs of tungsten. The reddish structures are

polysilicon gates, and the solid at the bottom is the crystalline silicon bulk.

The semiconductors of the periodic table of the chemical elements were

identified as the most likely materials for a solid state vacuum tube by researchers

like William Shockley at Bell Laboratories which stated in the 1930s. Starting with

copper oxide, proceeding to germanium, then silicon, the materials were

systematically studied in 1940s and 1950s. Today, silicon monocrystals are the

main substrate used for integrated circuits (ICs) although materials involving some

III-V group elements such as gallium arsenide are used for specialized applications

like LEDs, lasers, solar cells and the highest-speed integrated circuits etc. It took

decades to creating such crystals without defects in the semiconducting materials.

23

Semiconductors ICs are fabricated in a layer process which include standardize

the procedures following key process steps: (a) Imaging (b) Deposition (c) Etching

The main steps are supplemented by doping and cleaning. In many designs

mono-crystal silicon wafers (or for special applications, silicon on sapphire or

gallium arsenide wafers) are used as the substrate. Photolithography is used to mark

different areas of the substrate to be doped to have polysilicon, insulators or metal

(typically aluminum) tracks deposited on them.

Integrated circuits are composed of many overlapping layers, each defined by

photolithography, and normally shown in different colors. Some layers mark where

various dopants are diffused into the substrate (called diffusion layers), some define

where additional ions are implanted (implant layers), some define the conductors

(polysilicon or metal layers), and some define the connections between the

conducting layers (via contact layers). All components are constructed from a

specific combination of these layers.

In a self-aligned CMOS process, a transistor is formed wherever the gate layer

(polysilicon or metal) crosses a diffusion layer.

Capacitive structures, similar to the parallel conducting plates of a traditional

electrical capacitor, are formed according to the area of the "plates", with insulating

material between the plates. Capacitors of a wide range of sizes are common on ICs.

Meandering stripes of varying lengths are sometimes used to form on-chip

resistors, though most logic circuits do not need any resistors. The ratio of the

length of the resistive structure to its width, combined with its sheet resistivity,

determines the resistance.

Rarely, inductive structures can be built as tiny on-chip coils, or simulated by

gyrators.

Since a CMOS device only draws current on the transition between logic states,

CMOS devices consume much less current than bipolar devices.

A random access memory is the most regular type of integrated circuit; the

highest density devices are thus memories; but even a microprocessor will have

24

memory on the chip. (See the figure fabrication 1.7.9) Although the structures are

intricate – with widths which have been shrinking for decades – the layers remain

much thinner than the device widths. The layers of material are fabricated much like

a photographic process, although light waves in the visible spectrum cannot be used

to "expose" a layer of material, as they would be too large for the features. Thus

photons of higher frequencies (typically ultraviolet) are used to create the patterns

for each layer. Because each feature is so small, electron microscope are essential

tools for a process engineer who might be debugging a fabrication process.

Each device is tested before packaging using Automated Test Equipment

(ATE), in a process known as wafer testing, or wafer probing. The wafer is then cut

into rectangular blocks, each of which is called a die. Each good die (plural dice,

dies, or die) is then connected into a package using aluminum (or gold) bond wires

which are welded to pads, usually found around the edge of the die. After

packaging, the devices go through final testing on the same or similar ATE used

during wafer probing. Test cost can account for over 25% of the cost of fabrication

on lower cost products, but can be negligible on low yielding, larger, and/or higher

cost devices.

Arnand 2005, a fabrication facility (commonly known as a semiconductor lab)

costs over a billion US Dollars to construct [16], because much of the operation is

automated. The most advanced processes employ the following techniques:

The wafers are up to 300 mm in diameter (wider than a common dinner plate).

Use of 65, nanometer or smaller chip manufacturing process. Intel, IBM, NEC

and AMD are using 45 nanometers for their CPU chips. IBM and AMD are in

development of a 45 nm process using immersion lithography.

Copper wiring replaces aluminum for interconnects besides. Low-K dielectric

insulators. Silicon on insulator (SOI) strained silicon in a process used by IBM

known as strained silicon directly on insulator (SSDOI)

25

1.7.10 Packaging:

The earliest integrated circuits were packaged in ceramic flat packs, which were

used for military for their reliability and small size for many years. Commercial

circuit packaging quickly moved to the dual in-line package (DIP), first in ceramic

and later in plastic. In the 1980s pin counts of VLSI circuits exceeded the practical

limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier

(LCC) packages. Surface mount packaging appeared in the early 1980s and became

popular in the late 1980s, using finer lead pitch with leads formed as either gull-

wing or J-lead, as exemplified by small-outline integrated circuit a carrier which

occupies an area about 30 – 50% less than an equivalent DIP, with a typical

thickness that is 70% less. This package has "gull wing" leads protruding from the

two long sides and a lead spacing of 0.050 inches.

In the late 1990s, PQEP and TSOP packages became the most common for high

pin count devices, though PGA packages are still often used for high-end

microprocessors. Intel and AMD are currently transitioning from PGA packages on

high-end microprocessors to land grid array (LGA) packages.

Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball

Grid Array packages, which allow for much higher pin count than other package

types, were developed in the 1990s. In an FCBGA package the die is mounted

upside-down (flipped) and connects to the package balls via a package substrate that

is similar to a printed-circuit board rather than by wires. FCBGA packages allow an

array of input-output signals (called Area-I/O) to be distributed over the entire die

rather than being confined to the die periphery.

Traces out of the die, through the package, and into the printed circuit board

have very different electrical properties, compared to on-chip signals. They require

special design techniques and need much more electric power than signals confined

to the chip itself.

When multiple dies are put in one package, it is called SiP, for System in

package. When multiple dies are combined on a small substrate, often ceramic, it's

26

called an MCM, or Multi-Chip Module. The boundary between a big MCM and a

small printed circuit board is sometimes fuzzy.

1.7.11 Legal protection of semiconductor chip layouts:

Main article: Semiconductor Chip Protection Act of 1984

Prior to 1984, it was not necessarily illegal to produce a competing chip with an

identical layout. As the legislative history for the Semiconductor Chip Protection

Act of 1984, or SCPA, explained, patent and copyright protection for chip layouts,

or topographies, were largely unavailable. This led to considerable complaint by

U.S. chip manufacturers--notably, Intel, which took the lead in seeking legislation,

along with the Semiconductor Industry Association (SIA)--against what they

termed "chip piracy."

In 1984, addition to US law, the SCPA, made called mask works (i.e., chip

topographies) protectable if registered with the U.S. Copyright Office. Similar rules

apply in most other countries that manufacture ICs.

1.7.12 Other developments:

In the 1980s programmable integrated circuits were developed. These devices

contain circuits whose logical function and connectivity can be programmed by the

user, rather than being fixed by the integrated circuit manufacturer. This allows a

single chip to be programmed to implement different LSI-type functions such as

logic gates, adders and resisters. Current devices named FPGAs (Field

Programmable Gate Arrays) can now implement tens of thousands of LSI circuits in

parallel and operate up to 550 MHz

The techniques perfected by the integrated circuits industry over the last three

decades have been used to create microscopic machines, known as MEMS. These

devices are used in a variety of commercial and military applications. Example

commercial applications include DLP projectors, inkjet printers, and accelerometers

used to deploy automobile airbags.

In the past, radios could not be fabricated in the same low-cost processes as

microprocessors. But since 1998, a large number of radio chips have been

27

developed using CMOS processes. Examples include Intel's DECT cordless phone,

or Atheros’s 802.11 cards.

Future developments seem to follow the multi-core multi-microprocessor

paradigm, already used by the Intel and AMD dual-core processors. Intel recently

unveiled a prototype, "not for commercial sale" chip that bears a staggering 80

microprocessors. Each core is capable of handling its own task independently of the

others. This is in response to the heat-versus-speed limit that is about to be reached

using existing transistor technology. This design provides a new challenge to chip

programming. X10is the new open-source programming language designed to assist

with this task [17].

1.7.13 Silicon graffiti:

Ever since ICs were created, some chip designers have used the silicon surface

area for surreptitious, non-functional images or words. These are sometimes

referred to as Chip Art, Silicon Art, Silicon Graffiti or Silicon Doodling.

Key industrial and academic data.

1.7.14 Notable ICs:

The 555common multivibrator sub-circuit (common in electronic timing

circuits). The 741 operational amplifier, 7400 series TTL logic building blocks,

4000series, the CMOS counterpart to the 7400 series (see also: 74HC00 series),

Intel 4004, the world's first microprocessor, which led to the famous 8080CPU and

then the IBMPC’s 8088, 80286, 486 etc.

The MOS Technology 6502 and Zilog, Z80 microprocessors, used in many

home computers of the early 1980s. The Motorola 6800 series of computer-related

chips, leading to the 68000 and 88000 series (used in some Apple computers).

1.8 MICROPROCESSOR:

A microprocessor incorporates most or all of the functions of a central

processing unit (CPU) on a single integrated circuit (IC). [18] The first

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microprocessors emerged in the early 1970s and were used for electronic

calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other

embedded uses of 4- and 8-bit microprocessors, such as terminals, printers, various

kinds of automation etc, followed rather quickly. Affordable 8-bit microprocessors

with 16-bit addressing also led to the first general purpose microcomputers in the

mid-1970s. The recent development of fast microprocessors is also linked to the

growing popularity of fourth generation programming languages.

Computer processors were for a long period constructed out of small and

medium-scale ICs containing the equivalent of a few to a few hundred transistors.

The integration of the whole CPU onto a single VLSI chip therefore greatly reduced

the cost of processing capacity. From their humble beginnings, continued increases

in microprocessor capacity have rendered other forms of computers almost

completely obsolete, with one or more microprocessor as processing element in

everything from the smallest embedded systems and handheld devices to the largest

mainframes and supercomputers.

Since the early 1970s, the increase in capacity of microprocessors has been

known to generally follow Moore’s Law, which suggests that the complexity of an

integrated circuit, with respect to minimum component cost, doubles every two

years [19]. In the late 1990s, and in the high-performance microprocessor segment,

heat generation, due to switching losses, static current leakage, and other factors,

emerged as a leading developmental constraint [20].

1.8.1 History First types:

Three projects arguably delivered a complete microprocessor at about the same

time, namely Intel’s 4004, the Texas Instruments (TI) TMS 1000, and Garrett

AiResearch’s Central Air Data Computer (CADC). Intel's 4004 is considered the

first microprocessor [21-22]. This first microprocessor costed the thousands of

dollars [23]. The first known advertisement for the 4004 is dated back to November

1971; which appeared in Electronic News [24]. The project that produced Intel's

29

first known microprocessor originated in 1969, when Busicom, a Japanese

calculator manufacturer, asked Intel to build a chip set for high-performance

desktop calculators. Busicom's original design called for a dozen different logic and

memory chips. Ted Hoff, the Intel engineer was assigned this project, who believed

the design was not cost effective. His solution to problem was to simplify the design

and produce a programmable processor capable of creating a set of complex,

special-purpose calculator chips. Together with Masatoshi Shima and Federico

Faggin, later the founder of Zilog, Hoff came up with a four-chip design; a ROM

for custom application programs, a RAM for processing data, an I/O device, and an

unnamed 4-bit central processing unit which was known as a "microprocessor"[25].

The Smithsonian Institution says TI engineers Gary Boone and Michael Cochran

succeeded in creating the first microcontroller (also called a microcomputer) in

1971. The result of their work was the TMS 1000 which went commercial in 1974

[26]. Ray Holt, a graduate of California Polytechnic University in 1968, began his

computer design career with the F14 CADC. The central air data computer was

shrouded in secrecy for over 30 years from its creation (the year being 1968), it was

not publicly known until 1998. At the request of Mr. Ray Holt, the US Navy

allowed the documents into the public domain. Since then many debates have

argued that this was, in fact, the first microprocessor [27]. The scientific papers and

literature published around 1971 reveal that the MP944 digital processor used for

the F-14 Tomcat aircraft of the US Navy qualifies as the “first microprocessor”.

Although interesting, it was not a single-chip processor, and was not general

purpose – it was more like a set of parallel building blocks you could use to make a

special-purpose DSP form. It indicates that today’s industry theme of converging

DSP-microcontroller architectures was started in 1971[28]. This convergence of

DSP and microcontroller architectures is known as a Digital Signal Controller.

In 1968, Garrett AiResearch, with designer Ray Holt and Steve Geller, were

invited to produce a digital computer to compete with electromechanical systems

then under development for the main flight control computer in the US Navy’s new

30

F-14 Tomcat fighter. The design was complete by 1970, and used a MOS-based

chipset as the core CPU. The design was significantly (approximately 20 times)

smaller and much more reliable than the mechanical systems. It competed well with

other systems, and was used in all of the early Tomcat models. This system

contained "a 20-bit, pipelined, parallel multi-microprocessor". However, the system

was considered so advanced that the Navy refused to allow publication of the

design until 1997. For this reason the CADC, and the MP944 chipset it used, are

fairly unknown even today. TI developed the 4-bit TMS 1000, and stressed pre-

programmed embedded applications, introducing a version called the TMS1802NC

on September 17, 1971, which implemented a calculator on a chip. The Intel chip

was the 4-bit 4004, released on November 15, 1971, developed by Federico Faggin

and Ted Hoff. The manager of the design team was Leslie L. Vadasz.

TI filed for the patent on the microprocessor. Gary Boone was awarded U.S.

Patent 3,757,306 for the single-chip microprocessor architecture on September 4,

1973. It may never be known which company actually had the first working

microprocessor running on the lab bench. In both 1971 and 1976, Intel and TI

entered into broad patent cross-licensing agreements, with Intel paying royalties to

TI for the microprocessor patent. A nice history of these events is contained in court

documentation from a legal dispute between Cyrix and Intel, with TI as intervenor

and owner of the microprocessor patent.

Interestingly, a third party (Gilbert Hyatt) was awarded a patent which might

cover the "microprocessor". See a webpage claiming an invention pre-dating both

TI and Intel, describing a "microcontroller". According to a rebuttal and a

commentary, the patents was later invalidated, but not before substantial royalties

were paid out.

A computer-on-a-chip is a variation of a microprocessor which combines the

microprocessor core (CPU), some memory, and I/O (input/output) lines, all on one

chip. It is also called as micro-controller. The computer-on-a-chip patent, called the

"microcomputer patent" at the time, U.S. Patent 4,074,351, was awarded to Gary

31

Boone and Michael J. Cochran of TI. Aside from this patent, the standard meaning

of microcomputer is a computer using one or more microprocessors as its CPU(s),

while the concept defined in the patent is perhaps more akin to a microcontroller.

According to a history of Modern Computing, (MIT Press), pp. 220–21,Intel

entered into a contract with Computer Terminals Corporation, later called Data

point, of San Antonio TX, for a chip for a terminal they were designing. Data point

later decided not to use the chip, and Intel marketed it as the 8008 in April, 1972.

This was the world's first 8-bit microprocessor. It was the basis for the famous

“Mark-8” computer kit advertised in the magazine Radio-Electronics in 1974. The

8008 and its successor, the world-famous 8080, opened up the microprocessor

component marketplace.

1.8.2 General purpose:

In April 1974, Intel introduced the 8-bit 8080, the first general-purpose

microprocessor. With the ability to execute 290,000 instructions per second and

64K bytes of addressable memory, the 8080 was the first microprocessor with the

speed, power, and efficiency to become a key tool for designers. Development labs

set up by Hamilton/Avnet, Intel's first microprocessor distributor, showcased the

8080 and provided a broad customer base which contributed to its becoming the

industry standard. A key factor in the 8080's success was its role in the introduction

in January 1975 of the MITS Altair 8800, the first personal computer. It used the

powerful 8080 microprocessor and established the precedent that personal

computers must be easy to expand. With its increased sophistication, expandability,

and an incredibly low price of $395, the Altair 8800 proved the viability of home

computers [29-30].

1.8.3 Notable 8-bit designs:

The 4004 was later followed in 1972 by the 8008, the world's first 8-bit

microprocessor. These processors are the precursors to the very successful Intel

8080 (1974), Zilog Z80 (1976), and derivative Intel 8-bit processors. The competing

32

Motorola 6800 was released August 1974 and the similar MOS Technology 6502 in

1975 (designed largely by the same people). The 6502 rivaled the Z80 in popularity

during the 1980s.

A low overall cost, small packaging, simple computer bus requirements, and

sometimes circuitry otherwise provided by external hardware (the Z80 had a built in

memory refresh) allowed the home computer "revolution" to accelerate sharply in

the early 1980s, eventually delivering such inexpensive machines as the Sinclair,

which sold for US$99.

The Western Design Center, Inc. (WDC) introduced the CMOS 65C02 in 1982

and licensed the design to several firms. It became the core of the Apple IIc and IIe

personal computers, medical implantable grade pacemakers and defibrillators,

automotive, industrial and consumer devices. WDC pioneered the licensing of

microprocessor technology which was later followed by ARM and other

microprocessor Intellectual Property (IP) providers in the 1990’s.

Motorola introduced the MC6809 in 1978, an ambitious and thought through 8-

bit design source compatible with the 6800 and implemented using purely hard-

wired logic. (Subsequent 16-bit microprocessors typically used microcode to some

extent, as design requirements were getting too complex for hard-wired logic only)

[31].

Another early 8-bit microprocessor was the Signetics 2650, which enjoyed a

brief surge of interest due to its innovative and powerful instruction set architecture.

8086

A seminal microprocessor in the world of spaceflight was RCA’s RCA 1802

(aka CDP1802, RCA COSMAC) (introduced in 1976) which was used in NASA's

Voyager and Viking space probes of the 1970s, and onboard of Galileo probe sent

to Jupiter (launched 1989, arrived 1995). RCA COSMAC was the first to

implement C-MOS technology. The CDP1802 was used because it could be run at

very low power, and because its production process (Silicon on Sapphire) ensured

much better protection against cosmic radiation and electrical discharges than that

33

of any other processor of the era. Thus, the 1802 is said to be the first radiation-

hardened microprocessor.

The RCA 1802 had what is called a static design, meaning that the clock

frequency could be made arbitrarily low, even to 0 Hz, a total stop condition. This

let the Voyager/Viking/Galileo spacecraft use minimum electric power for long

uneventful stretches of a voyage. Timers and/or sensors would improve the

performance of the processor in time for important tasks, such as navigation

updates, attitude control, data acquisition, and radio communication [32].

1.8.4 16-bit designs:

The first multi-chip 16-bit microprocessor was the National Semiconductor

IMP-16, introduced in early 1973. An 8-bit version of the chipset was introduced in

1974 as the IMP-8. During the same year, National introduced the first 16-bit

single-chip microprocessor, the National Semiconductor PACE, which was later

followed by an NMOS version, the INS8900.

Other early multi-chip 16-bit microprocessors include one used by Digital

Equipment Corporation (DEC) in the LSI-11OEM board set and the packaged PDP

11/03 minicomputer, and the Fairchild Semiconductor Micro Flame 9440, both of

which were introduced in the 1975 to 1976 timeframe.

The first single-chip 16-bit microprocessor was TI's TMS 9900, which was also

compatible with their TI-990 line of minicomputers. The 9900 was used in the TI

990/4 minicomputer, the TI-99/4A home computer, and the TM990 line of OEM

microcomputer boards. The chip was packaged in a large ceramic 64-pin DIP

package, while most 8-bit microprocessors such as the Intel 8080 used the more

common, smaller, and less expensive plastic 40-pin DIP. A follow-on chip, the

TMS 9980, was designed to compete with the Intel 8080, had the full TI 990 16-bit

instruction set, used a plastic 40-pin package, moved data 8 bits at a time, but could

only address 16 KB. A third chip, the TMS 9995, was a new design. The family

later expanded to include the 99105 and 99110.

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The Western Design Center, Inc. (WDC) introduced the CMOS 65816, 16-bit

upgrade of the WDC CMOS 65C02 in 1984. The 65816, 16-bit microprocessor was

the core of the Apple IIgs and later the Super Nintendo Entertainment System,

making it one of the most popular 16-bit designs of all time.

Intel followed a different path, having no minicomputers to emulate, and

instead "upsized" their 8080 design into the 16-bit Intel 8086, the first member of

the x86 family which powers most modern PC type computers. Intel introduced the

8086 as a cost effective way of porting software from the 8080 lines, and succeeded

in winning much business on that premise. The 8088, a version of the 8086 that

used an external 8-bit data bus, was the microprocessor in the first IBM PC, the

model 5150. Following up their 8086 and 8088, Intel released the 80186, 80286

and, in 1985, the 32-bit 80386, cementing their PC market dominance with the

processor family's backwards compatibility.

The integrated microprocessor memory management unit (MMU) was

developed by Childs et al. of Intel, and awarded US patent number 4,442,484.

1.8.5 32-bit designs:

16-bit designs were in the markets only briefly when full 32-bit

implementations started to appear.

The most significant of the 32-bit designs is the MC68000, introduced in 1979.

The 68K, as it was widely known, had 32-bit registers but used 16-bit internal data

paths, and a 16-bit external data bus to reduce pin count, and supported only 24-bit

addresses. Motorola generally described it as a 16-bit processor, though it clearly

has 32-bit architecture. The combination of high performance, large (16 megabytes

(2^24)) memory space and fairly low costs made it the most popular CPU design of

its class. The Apple Lisa and Macintosh designs made use of the 68000, as did a

host of other designs in the mid-1980s, including the Atari ST and Commodore

Amiga.

35

The world's first single-chip fully-32-bit microprocessor, with 32-bit data paths,

32-bit buses, and 32-bit addresses, was the AT & T Bell Labs BELLMAC-32A,

with first samples in 1980, and general production in 1982 (See this bibliographic

reference and this general reference). After the divestiture of AT&T in 1984, it was

renamed the WE 32000 (WE for Western Electric), and had two follow-on

generations, the WE 32100 and WE 32200. These microprocessors were used in the

AT & T 3B5 and 3B15 minicomputers; in the 3B2, the world's first desktop super

microcomputer; in the "Companion", the world's first 32-bit laptop computer; and in

"Alexander", the world's first book-sized super microcomputer, featuring ROM-

pack memory cartridges similar to today's gaming consoles. All these systems ran

the UNIX System V operating system.

Intel's first 32-bit microprocessor was the iAPX 432, which was introduced in

1981 but was not a commercial success. It had an advanced capability-based object-

oriented architecture, but poor performance compared to other competing

architectures such as the Motorola 68000.

Motorola's success with the 68000 led to the MC68010, which added virtual

memory support. The MC68020, introduced in 1985 added full 32-bit data and

address busses. The 68020 became hugely popular in the UNIX super

microcomputer market, and many small companies (e.g., Altos, Charles River Data

Systems) produced desktop-size systems. The MC68030 was introduced next,

improving upon the previous design by integrating the MMU into the chip. The

continued success led to the MC68040, which included an FPU for better math

performance. A 68050 failed to achieve its performance goals and was not released,

and the follow-up MC68060 was released into a market saturated by much faster

RISC designs. The 68K family faded from the desktop in the early 1990s.

Other large companies designed the 68020 and follow-on into embedded

equipment. At one point, there were more 68020s in embedded equipment than

there were Intel Pentiums in PCs (See this webpage for this embedded usage

information). The Cold Fire processor cores are derivatives of the venerable 68020.

36

During this time (early to mid 1980s), National Semiconductor introduced a

very similar 16-bit pin out, 32-bit internal microprocessor called the NS 16032

(later renamed 32016), the full 32-bit version named the NS 32032, and a line of

32-bit industrial OEM microcomputers. By the mid-1980s, Sequent introduced the

first symmetric multiprocessor (SMP) server-class computer using the NS 32032.

This was one of the design's few wins, and it disappeared in the late 1980s.

The MIPS R2000 (1984) and R3000 (1989) were highly successful 32-bit RISC

microprocessors. They were used in high-end workstations and servers by SGI,

among others.

Other designs included the interesting Zilog Z8000, which arrived too late to

market to stand a chance and disappeared quickly.

In the late 1980s, "microprocessor wars" started killing off some of the

microprocessors. Apparently, with only one major design win, Sequent, the NS

32032 just faded out of existence, and Sequent switched to Intel microprocessors.

From 1985 to 2003, the 32-bit x86 architectures became increasingly dominant

in desktop, laptop, and server markets and these microprocessors became faster and

more capable. Intel had licensed early versions of the architecture to other

companies, but declined to license the Pentium, so AMD and Cyrix built later

versions of the architecture based on their own designs. During this span, these

processors increased in complexity (transistor count) and capability

(instructions/second) by at least three orders of magnitude. Intel's Pentium line is

probably the most famous and recognizable 32-bit processor model, at least with the

public at large.

1.8.6 64-bit designs in personal computers:

While 64-bit microprocessor designs have been in use in several markets since

the early 1990s, the early 2000s saw the introduction of 64-bit microchips targeted

at the PC market.

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With AMD's introduction of a 64-bit architecture backwards-compatible with

x86, x86-64 (now called AMD64), in September 2003, followed by Intel's near

fully compatible 64-bit extensions (first called IA-32e or EM64T, later renamed

Intel 64), the 64-bit desktop era began. Both versions can run 32-bit legacy

applications without any performance penalty as well as new 64-bit software. With

operating systems Windows XPx64, Windows Vista x64, Linux, BSD and Mac OS

X that run 64-bit native, the software is also geared to fully utilize the capabilities of

such processors. The move to 64 bits is more than just an increase in register size

from the IA-32 as it also doubles the number of general-purpose registers.

The move to 64 bits by PowerPC processors had been intended since the

processors' design in the early 90s and was not a major cause of incompatibility.

Existing integer registers are extended as are all related data pathways, but, as was

the case with IA-32, both floating point and vector units had been operating at or

above 64 bits for several years. Unlike what happened when IA-32 was extended to

x86-64, no new general purpose registers were added in 64-bit PowerPC, so any

performance gained when using the 64-bit mode for applications making no use of

the larger address space is minimal.

1.8.7 Multicore designs:

A different approach in improving a computer's performance is to add extra

processors, as in symmetric multiprocessing designs which have been popular in

servers and workstations since the early 1990s. Keeping up with Moore’s Law it is

becoming increasingly challenging as chip-making technologies approach the

physical limits of the technology.

In response, the microprocessor manufacturers look for other ways to improve

performance, in order to hold on to the momentum of constant upgrades in the

market.

A multi-core processor is simply a single chip containing more than one

microprocessor core, effectively multiplying the potential performance with the

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number of cores (as long as the operating system and software is designed to take

advantage of more than one processor). Some components, such as bus interface

and second level cache, may be shared between cores. Because the cores are

physically very close they interface at much faster clock rates compared to discrete

multiprocessor systems, improving overall system performance.

In 2005, the first mass-market dual-core processors were announced and as of

2007 dual-core processors are widely used in servers, workstations and PCs while

quad-core processors are now available for high-end applications in both the home

and professional environments.

Sun Microsystems has released the Niagara and Niagara 2 chips, both of which

feature an eight-core design. The Niagara 2 supports more threads and operates at

1.6 GHz.

High-end Intel Xeon processors that are on the LGA771 socket are DP (dual

processor) capable, as well as the new Intel Core 2 Extreme QX9775 also used in

the Mac Pro by Apple and the Intel Skull trail motherboard [33].

1.8.8 RISC:

In the mid-1980s to early-1990s, a crop of new high-performance RISC

(Reduced Instruction Set Computer) microprocessors appeared influenced by

discrete RISC-like CPU designs such as the IBM 801 and others. RISC

microprocessors were initially used in special purpose machines and Unix

workstation, but then gained wide acceptance in other roles.

The first commercial microprocessor design was released either by MIPS

Technologies, the 32-bit R2000 (the R1000 was not released) or by Acorn

computers, the 32-BIT ARM 2x in 1986. The R3000 made the design truly

practical, and the R4000 introduced the world's first 64-bit design. Competing

projects would result in the IBM POWER and Sun SPARC systems, respectively.

Soon every major vendor was releasing a RISC design, including the AT & T

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CRISP, AMD 29000, Intel i860 and Intel i960, Motorola 88000, DEC Alpha and

the HP_PA.

Market forces have "weeded out" many of these designs, with almost no

desktop or laptop RISC processors and with the SPARC being used in Sun designs

only. MIPS is primarily used in embedded systems, notably in Cisco routers. The

rest of the original crop of designs has disappeared. Other companies have attacked

niches in the market, notably ARM, originally intended for home computer use but

since focused on the embedded processor market. Today RISC designs based on the

MIPS, ARM or PowerPC is used in the majority of embedded 32-bit devices,

although not in the large quantities in which embedded 8-bit devices are produced

(whether CISC or RISC).

As of 2007, two 64-bit RISC architectures are still produced in volume for non-

embedded applications: SPARC and Power Architecture. The RISC-like Itanium is

produced in smaller quantities. The vast majority of 64-bit microprocessors are now

x86-64 CISC designs from AMD and Intel.

1.8.9 Special-purpose designs:

Though the term "microprocessor" has traditionally referred to a single- or

multi-chip CPU or system-on-a-chip (SOC), several types of specialized processing

devices have followed from the technology. The most common examples are

microcontrollers, digital signal processor (DSP) and graphics processing units

(GPU). Many examples of these are either not programmable, or have limited

programming facilities. For example, in general GPUs through the 1990s were

mostly non-programmable and have only recently gained limited facilities like

programmable vertex shaders. There is no universal consensus on what defines a

"microprocessor", but it is usually safe to assume that the term refers to a general-

purpose CPU of some sort and not a special-purpose processor unless specifically

noted.

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1.8.10 Market statistics:

In 2003, about $44 billion (USD) worth of microprocessors were manufactured

and sold. [20] Although about half of that money was spent on CPUs used in

desktop or laptop personal computers, those count for only about 0.2% of all CPUs

sold.

Silicon Valley has an old saying: "The first chip costs a million dollars; the

second one costs a nickel." In other words, most of the cost is in the design and the

manufacturing setup: once manufacturing is underway, it costs almost nothing.

[Citation needed]

About 55% of all CPUs sold in the world are 8-bit microcontrollers. Over 2

billion 8-bit microcontrollers were sold in 1997. [21]

Less than 10% of all the CPUs sold in the world are 32-bit or more. Of all the

32-bit CPUs sold, about 2% are used in desktop or laptop personal computers. Most

microprocessors are used in embedded control applications such as household

appliances, automobiles, and computer peripherals. "Taken as a whole, the average

price for a microprocessor, microcontrollers, or DSP is just over $6." [22]

1.8.11 Memory Chips:

Weather simple or complex, every microprocessor- based system has a

memory system. Almost all systems contain two main types of memory: read only

memory (ROM) other type of read only memory is called flash memory (EEPROM)

and random asses’ memory (ROM) is of two types 1. Static random asses’ memory

(SRAM). 2. Dynamic random asses’ memory (DRAM). It is also called the read /

writes memory. Read only memory contains system software and permanent system

data, while RAM contains the temporary data and applications software. We can

demonstrate the memory interface to an 8-bit, 16bit, 32-bit and 64-bitdata bus using

various memory address sizes. This allow virtually any microprocessor to interfaced

to any memory system.[34]

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Introduction 1.7.1 Invention 1.7.2 V.S.I. 1.7.4

Integrated circuits 1.7.4 Classification 1.7.8 Fabrication 1.7.9

Packaging 1.7.10 History: First type 1.8.1

32-bit design 1.8.5 Multicore designs 1.8.7

Figure 1.3 Introduction, Fabrication and designs of integrated circuits.

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Jack Kilby’s original integrated circuit 1.7.2

Upper interconnect layers on an Intel 80486DX2 microprocessor die 1.7.4.

The integrated circuit from an Intel 8742, an 8-bit microcontroller that includes

a CPU running at 12 MHz, 128 bytes of RAM, 2048 bytes of EPROM, and I/O

in the same chip 1.7.6.

A CMOS 4000 IC in a DIP 1.7.8

Early USSR made integrated circuit 1.7.10.

The 4004 with cover removed (left) and as actually used (right) 1.8.1,

Upper interconnect layers on an Intel 80486 DX2 die 1.8.5.

Pentium D dual core processors 1.8.7.

1.9 WHAT IS SPICE?

SPICE is program that simulates electronics circuits on your PC. We can view

any voltage or current waveform in our circuit. SPICE calculates the voltage and

current versus time (Transient Analysis) or versus frequency (AC Analysis). Most

SPICE programs also perform other analysis like DC, Sensitivity, Noise and

Distortion.

SPICE stands for Simulation Program with Integrated Circuit Emphasis.

Researchers at the University of California, Berkeley developed this computer

program during the mid-70s. What drove this development? This arrival of the

integrated circuit demanded a method to test and tweak circuit designs before the

expensive fabrication process.

Today, SPICE is available from many venders who have added schematics

drawing tools to the front end and graphics postprocessors to plot the results. SPICE

simulators and applications have expanded to analog and digital circuits, microwave

devices and electromechanical systems [35].

1.9.1 Why use spice:

For many years electronic instruments have been easily indented products.

Although they ranged in size and functionality, they all tended to be box-shaped

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objects with a control panel and a display. Stand-alone electronic instruments are

very powerful, expensive and designed to perform one or more specific tasks

denned by the vendor. However, the user generally cannot extend or customize

them. The knobs and buttons on the instrument, the built-in circuitry, and the

functions available to the user, all of these are septic to the nature of the instrument.

In addition, special technology and costly components must be developed to build

these instruments, making them very expensive and hard to adapt.

Widespread adoption of the PC over the past twenty years has given rise to a

new way for scientists and engineers to measure and automate the world around

them. One major development resulting from the ubiquity of the PC is the concept

of virtual instrumentation. A virtual instrument consists of an industry-standard

computer or workstation equipped with the-shelf application software, cost-

effective hardware such as plug-in boards, and driver software |which together

perform the functions of traditional instruments. Today virtual instrumentation is

coming of age, with engineers and scientists using virtual instruments in literally

hundreds of thousands of applications around the globe, resulting in faster

application development, higher quality products and lower costs. Virtual

instruments represent a fundamental shift from traditional hardware-centered

instrumentation systems towards software-centered systems that exploit the

computing power, productivity, display and connectivity capabilities of popular

desktop computers and workstations.

Although PC and integrated circuit technologies experienced significant

advances in the past two decades, it is the software that makes possible building

virtual instruments on this foundation. Engineers and scientists are no longer limited

by traditional axe-function instruments.

Now they can build measurement and automation systems that suit exactly their

special needs.

SPICE is a great tool for learning electronics. You can increase your

understanding circuits as you play and tinker with them. Experiment! Modify the

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circuits and see what happens! How long does it take? Change a resistor value and

see the effect on a circuit in seconds.

Ideally, we would actually build and test actual circuits to understand all the

behaviors. However, you would need the breadboards, components and time to wire

the circuits. Actual circuits also require expensive equipments like power supplies,

signal generators and oscilloscopes. It may be difficult to physically breadboard

every circuit you encounter.

You spend hours building an actual circuits and only get a simple concept from

it, whereas, SPICE provides the insight in seconds. SPICE can be yours “Virtual”

breadboard. Even if you have a short time to spare, you can cover several circuit

principals and applications [36, 37, 38, 39, 40].

The use of computer-aided design tools has proven to be invaluable in the

development of new technologies and circuit design. Computer simulations have

emerged as a very elegant way to aid device, circuit and system design engineers.

PSpice (PC Version, Simulation Program with Integrated Circuit and Emphasis) is a

widely used circuit simulation tool. It provides facilities for analyzing circuit

performance under various operating conditions. DC, AC and Transient analysis are

among the important features of PSpice.

It also facilitates circuit analysis at different ambient temperatures by a simple

command (TEMP). Further the circuit elements are represented by models whose

parameters can be appropriately chosen. This facility would help in analyzing the

circuit behavior under specified different environmental conditions by proper

choice of model parameters. [41].

1.10 MOTIVATION OF PRESENT STUDY:

Electronics is encountered in everyday life in the form of telephones, radios,

televisions, audio equipment, home appliances, computers, and equipment for

industrial control and automation. Electronics have become the stimuli for and an

integral part of modern technological growth and development. The field of

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electronics deals with the design and applications of electronic devices. But today’s

the requirement of people is to buy the new gadgets from the market. Therefore

there is too much competition in the market. People require more and more facilities

provided by modern electronics and electrical circuitry used in them. These gadgets

which range from instruments used in medical, educational, research, defense, home

appliances and our daily life too. So it is essential to get the more and more

information about the different electronic circuits used in there gadgets.

This facility to using a computer to simulate the behavior of electrical or

electronic circuits has advantages over conventional methods. A computer can

perform millions of operations per second and is faster than calculations by hand or

calculator. Together with a printer, results can be plotted or tabulated in minutes. In

addition, measurements which would be difficult or impossible to do on a real

circuit can be made. The advantage of using any program is that you still have to

design the circuit yourself, and results will only be as good as your initial circuit

input. Circuit simulation is the technique of predicting the behavior of a real circuit

by a computer program. Most of the simulators are based on various versions of

SPICE.

Circuit simulation is the technique of predicting the behavior of a real circuit by

a computer program. Most of simulators are based on various versions of SPICE

Aim of present work is to study the different spice software’s and finally

conclude that which is better for the use of the students as well as for common

people those who are interested in getting the elementary knowledge. They should

be familiar with the different types of electronic circuits. Many a time’s users

cannot have special components with them. Sometimes actual experimentation is

not possible. But the use of spice gives them the idea of these timings by wires

virtual components. Once we get the proper idea of a same circuit in different spice

software’s, and there virtual outputs, we can construct the proper circuit by using

the proper idea about the component with in minimum time of desired output and

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required tolerance. These different software’s give the facility performing the

different kinds of analysis.

Present studies are focused on different spice like PSpice, B2 Spice, Top Spice,

Tina and Circuit Maker. For simulation studies different circuits are chosen which

contains the components from resister to ICs.

1.11 ORGANIZATION OF THE THESIS:

Present work in the thesis is organized in to seven chapters.

The first chapter gives the brief history and the developments in the

electronics. Starting from discovery of an electron, vacuum tubes, semiconductors,

diodes, transistors, integrated circuits, microprocessors, memory chips etc.

Interfacing of different spice software’s are discussed.

The second chapter focuses on the basic information about the PSpice, B2

Spice, Top Spice, Tina and Circuit Maker. The abilities of these software’s for

performing the different types of analysis are explained.

The third chapter includes the study of square wave generator and triangular

wave generator circuits which are often used in the testing and characterization of

electronic devices and circuits. The theories, simulation, simulation results and

comparative studies are made.

The fourth chapter includes the study of Astable multivibrator & Voltage

regulator circuits which are often used in different electronic configurations. The

theories of simulation, simulation results and comparative studies are given.

The fifth chapter covers the comparative study of Wein bridge oscillator & R

C coupled amplifier circuits in different spice software. These are often used in

different electronic configurations. The theories, simulation, simulation results and

comparative studies are discussed.

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The sixth chapter covers the comparative discussion of the theoretical and

simulation results, features of different software’s, comparison charts and the actual

results.

The seventh chapter gives the conclusion and summary of the present work.

The future scope and future directions are discussed.

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