Tieng Anh Chuyen Nghanh

8/2/2019 Tieng Anh Chuyen Nghanh

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UNIT 1

TRANSISTOR

1. Definition

In electronics, a transistor is a semi-

conductor device commonly used to amplify or

switchelectronic signals. A transistor is made of a

solid piece of a semiconductor material, with at

least threeterminalsfor connection to an external

circuit. A voltage or current applied to one pair of

the transistor's terminals changes the current

flowing through another pair of

terminals. Because the controlled (output) powercan be much more than the controlling

(input) power, the transistor provides amplification of a signal.

2. History

The first patent for the field-effect transistor principle was filed in Canada by Austrian-

Hungarian physicist, Julius Edgar Lilienfeld on 22 October 1925. But Lilienfeld did not

publish any research articles about his devices. In 1934 German physicist Dr.Oskar Heil

patented another field-effect transistor.

On 17 November 1947 John Bardeen and Walter Brattain, at AT&TBell Labs,

observed that when electrical contacts were applied to a crystal ofgermanium, the output

power was larger than the input. William Shockley saw the potential in this and worked

over the next few months

greatly expanding the knowledge of

semiconductors and could be described as the

father of the transistor, a legal papers from the

Bell Labs patent show that William Shockley

and Gerald Pearson had built operational

versions from Lilienfeld's patents.

1

Fig. 1 Some types of transistor

Fig 2. Transistor in Lilienfelds

experience
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The first silicon transistor was produced by Texas Instruments in 1954. This was

the work ofGordon Teal, an expert in growing crystals of high purity, who had

previously worked at Bell Labs. The firstMOS transistor actually built was by Kahng and

Atalla at Bell Labs in 1960.

The transistor is considered by many to be the greatest invention of the twentieth-

century, and some consider it is one of the most important technological breakthroughs in

human history.It is the key active component in practically all modern electronics and is

the fundamental building block of modern electronic devices like radio, telephone,

computer etc. Its importance in today's society rests on its ability to be mass produced

using a highly automated process (in fabrication) that achieves astonishingly low per-

transistor costs. Some transistors are packaged individually but most are found in

integrated circuits.

Although several companies each produce over a billion individually packaged

(known as discrete) transistors every year,the vast majority of transistors produced are in

integrated circuits (often shortened toIC, microchips or simply chips) along with diodes,

resistors, capacitors and otherelectronic components to produce complete electronic

circuits. A logic gate consists of up to about twenty transistors whereas an advanced

microprocessor, as of 2006, can use as many as 1.7 billion transistors ( MOSFETs).

"About 60 million transistors were built this year [2002], for [each] man, woman, and

child on Earth."

The transistor's low cost, flexibility, and reliability have made it a ubiquitous

device. Transistorized mechatronic circuits have replaced electromechanical devices in

controlling appliances and machinery. It is often easier and cheaper to use a standard

microcontroller and write a computer program to carry out a control function than to

design an equivalent mechanical control function.

3. Applications

Thebipolar junction transistor, or BJT, was the most commonly used transistor in

the 1960s and 70s, after MOSFETs became widely available, the BJT remained the

transistor of choice for many analog circuits such as simple amplifiers because of their

greater linearity and ease of manufacture. Desirable properties of MOSFETs, such as their

utility in low-power devices, usually in the CMOS configuration, allowed them to capture

nearly all market share for digital circuits; more recently MOSFETs have captured most

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analog and power applications as well, including modern clocked analog circuits, voltage

regulators, amplifiers, power transmitters, motor drivers, etc.

The essential usefulness of a transistor comes from its ability to use a small signal

applied between one pair of its terminals to control a much larger signal at another pair of

terminals. This property is calledgain. A transistor can control its output in proportion to

the input signal, that is, can act as an amplifier. Or, the transistor can be used to turn

current on or off in a circuit as an electrically controlled switch, where the amount of

current is determined by other circuit elements.

The two types of transistors have slight differences in how they are used in a

circuit. A bipolar transistor has terminals labeled base, collector, and emitter. A small

current at the base terminal (that is, flowing from the base to the emitter) can control or

switch a much larger current between the collector and emitter terminals. For a field-

effect transistor, the terminals are labeled gate, source, and drain, and a voltage at the

gate can control a current between source and drain.

The fig. 3 represents a typical bipolar

transistor in a circuit. Charge will flow

between emitter and collector terminals

depending on the current in the base. Since

internally the base and emitter connections

behave

like a semiconductor diode, a voltage drop develops between base and emitter while the

base current exists. The size of this voltage depends on the material the transistor is made

from, and is referred to as VBE

3.1. Transistor as a switch

Transistors are commonly used as electronic switches, for both high power

applications including switched-mode power supplies and low power applications such as

logic gates.

Using the simple transistor circuit it can be seen from the graph, from point A to

point B, as the base voltage rises the base and collector current rise exponentially (the A-

B segment should be curved), but the collector voltage simultaneously drops because of

the collector resistor. Relevant equations:

3

Fig 3. Typical circuit of transistor
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Following the Kirhoff laws, one can write expression:

VRC = IC RC

VRC + VCE = VCC

If VCE could fall to 0 (perfect closed switch) then Ic could go no higher than VCC /

RC, even with higher base voltage and current. The transistor is then said to be saturated.

In actuality VCE drops to roughly VBE 2, rising with higher collector currents. Hence,

values of input voltage can be chosen such that the output is either completely off, or

completely on. The transistor is acting as a switch, and this type of operation is common

indigital circuits where only "on" and "off" values are relevant.

3.2. Transistor as an amplifier

The above common emitter amplifier is designed so that a small change in voltage

in (Vin) changes the small current through the base of the transistor and the transistor's

current amplification combined with the properties of the circuit mean that small swings

in Vin produce large changes in Vout.

It is important that the operating parameters of the transistor are chosen and thecircuit designed such that as far as possible the transistor operates within a linearportion

of the graph, such as that shown between A and B, otherwise the output signal will suffer

distortion.

Various configurations of single transistor amplifier are possible, with some

providing current gain, some voltage gain, and some both.

From mobile phones to televisions, vast numbers of products include amplifiers

for sound reproduction, radio transmission, and signal processing. The first discrete

4

Fig. 4 The transistor works as a switch

A

B

VB

IBC
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transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio

fidelity gradually increased as better transistors became available and amplifier

architecture evolved. Modern transistor audio amplifiers of up to a few hundred watts are

common and relatively inexpensive. Some musical instrument amplifier manufacturers

mix transistors and vacuum tubes in the same circuit, as some believe tubes have a

distinctive sound.

4. Advantages

The key advantages that have allowed transistors to replace their vacuum tube

predecessors in most applications are

- Small size and minimal weight, allowing the development of miniaturized electronic

devices.

- Highly automated manufacturing processes, resulting in low per-unit cost.

- Lower possible operating voltages, making transistors suitable for small, battery-

powered applications.

- No warm-up period for cathode heaters required after power application.

- Lower power dissipation and generally greater energy efficiency.

- Higher reliability and greater physical ruggedness.

- Extremely long life. Some transistorized devices have been in service for more than 30

years.

- Complementary devices available, facilitating the design ofcomplemen-tary symmetry

circuits, something not possible with vacuum tubes.

- Insensitivity to mechanical shock and vibration, thus avoiding the problem of

microphonicsin audio applications.

5. Disadvantages

- Silicon transistors do not operate at voltages higher than about 1,000 volts (SiC devices

can be operated as high as 3,000 volts). In contrast, electron tubes have been developed

that can be operated at tens of thousands volts.

- High power, high frequency operation, such as used in over-the-air television

broadcasting, is better achieved in electron tubes due to improved electron mobilityin a

vacuum.

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- On average, a higher degree ofamplificationlinearity can be achieved in electron tubes

as compared to equivalent solid state devices, a characteristic that may be important in

high fidelityaudio reproduction.

- Silicon transistors are much more sensitive than electron tubes to an electromagnetic

pulse, such as generated by an atmospheric nuclear explosion.

Exercise 1:Answer the question following the text:

1. What is a transistor?

2. What are the transistors made of?

3. Why can transistors provide amplification of a signal?

4. Where are transistors used?

5. Which type of transistor was used in 1960s-1970s

6. What does MOSFET stand for?

7.Why is transistor used for amplifying signal?

8. What are the terminals of BJT ?

9. What are the terminals of FET?

10. What are the advantages of transistor compare to vacuum tube?

11.When was the first MOS transistor built?

12. How many transistors are in the advanced microprocessor in 2006?

Exercise 2:Identify the statements are True or False:

1. A transistor is made of a solid piece of a semiconductormaterial, with at least three

terminals for connection to an external circuit

2. The transistor is the fundamental building block of modern electronic devices like

radio,telephone, computerand other electronic systems

3. The transistor is considered as one of the most important technological breakthroughs

in human history.

4. Transistorized mechatronic circuits couldnt replace electromechanical devices in

controlling appliances and machinery

5. Transistors operating at high voltage not suitable for small, battery-powered

applications.

6
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6. Silicon transistors are much more sensitive than electron tubes to an electromagnetic

pulse

Exercise 3: Translate the text and summery in short paragraph.

UNIT 2

SENSOR

1. Definition

A sensor is a device that measures a physical quantity and converts it into a signal

which can be read by an observer or by an instrument. For example, a mercury

thermometer converts the measured temperature into expansion and contraction of a

liquid which can be read on a calibrated glass tube. A thermocouple converts temperature

to an output voltage which can be read by a voltmeter. For accuracy, all sensors need to

be calibrated against known standards.

Sensors are used in everyday objects

such as touch-sensitive elevator buttons and

lamps which dim or brighten by touching the

base. There are also innumerable applications

for sensors of which most people are never

aware. Applications include cars, machines,

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Fig. 5 Humidity sensor
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aerospace, medicine, manu-facturing and

robotics.

A sensor's sensitivity indicates how much the sensor's output changes when the

measured quantity changes. For instance, if the mercury in a thermometer moves 1 cm

when the temperature changes by 1 C, the sensitivity is 1 cm/C. Sensors that measure

very small changes must have very high sensitivities. Sensors also have an impact on

what they measure; for instance, a room temperature thermometer inserted into a hot cup

of liquid cools the liquid while the liquid heats the thermometer.

Sensors need to be designed to have a small

effect on what is measured; making the sensor

smaller often improves this and may introduce other

advantages. Technological progress allows more and

more sensors to be manufactured on a microscopic

scale as microsensors using MEMS (Micro Electro

MechanicalSystems) technology. In most

cases, a microsensor reaches a significantly higher speed and sensitivity compared with

macroscopic approaches. A good sensor obeys the following rules:

Is sensitive to the measured property

Is insensitive to any other property

Does not influence the measured property

Ideal sensors are designed to be linear. The output signal of such a sensor is

linearly proportional to the value of the measured property. Thesensitivity is then defined

as the ratio between output signal and measured property. For example, if a sensor

measures temperature and has a voltage output, the sensitivity is a constant with the unit[V/C]; this sensor is linear because the ratio is constant at all points of measurement. If

the sensor is not ideal, several types of deviations can be observed:

The sensitivity may in practice differ from the value specified. This is called a

sensitivity error, but the sensor is still linear.

Since the range of the output signal is always limited, the output signal will

eventually reach a minimum or maximum when the measured property exceeds the

8

Fig. 6 Thermometer
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limits. The full scale range defines the maximum and minimum values of the measured

property.

If the output signal is not zero when the measured property is zero, the sensor has

an offset or bias. This is defined as the output of the sensor at zero input.

If the sensitivity is not constant over the range of the sensor, this is called

nonlinearity. Usually this is defined by the amount the output differs from ideal

behavior over the full range of the sensor, often noted as a percentage of the full range.

If the deviation is caused by a rapid change of the measured property over time,

there is a dynamic error. Often, this behaviour is described with a bode plot showing

sensitivity error and phase shift as function of the frequency of a periodic input signal.

If the output signal slowly changes independent of the measured property, this is

defined asdrift.

Long term drift usually indicates a slow degradation of sensor properties over a

long period of time.

Noise is a random deviation of the signal that varies in time.

Hysteresis is an error caused by when the measured property reverses direction, but

there is some finite lag in time for the sensor to respond, creating a different offset error

in one direction than in the other.

If the sensor has a digital output, the output is essentially an approximation of the

measured property. The approximation error is also calleddigitization error.

If the signal is monitored digitally, limitation of the sampling frequency also can

cause a dynamic error.

The sensor may to some extent be sensitive to properties other than the property

being measured. For example, most sensors are influenced by the temperature of their

environment.

All these deviations can be classified as systematic errors or random errors.

Systematic errors can sometimes be compensated for by means of some kind of

calibration strategy. Noise is a random error that can be reduced by signal processing,

such as filtering, usually at the expense of the dynamic behavior of the sensor.

2. Resolution

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The resolution of a sensor is the smallest change it can detect in the quantity that it

is measuring. Often in a digital display, the least significant digit will fluctuate, indicating

that changes of that magnitude are only just resolved. The resolution is related to the

precision with which the measurement is made. For example, a scanning tunneling probe

(a fine tip near a surface collects an electron tunneling current) can resolve atoms and

molecules.

All living organisms contain biological sensors with functions similar to those of

the mechanical devices described. Most of these are specialized cells that are sensitive to:

Light, motion, temperature, magnetic fields, gravity, humidity, vibration, pressure,

electrical fields,sound, and other physical aspects of the external environment

Physical aspects of the internal environment, such asstretch, motion of the

organism, and position of appendages (proprioception)

Environmental molecules, including toxins, nutrients, andpheromones

Estimation of biomolecules interaction and some kinetics parameters

Internal metabolic milieu, such as glucose level, oxygen level, orosmolality

Internal signal molecules, such ashormones, neurotransmitters, and cytokines

Differences between proteins of the organism itself and of the envi-ronment or

alien creatures

Artificial sensors that mimic biological sensors by using a biological sensitive

component are calledbiosensors.


1. What is a sensor?

2. Where are sensors used?

3. What thing should be considered when making the sensors?

4. What properties the good sensors have

5. What is sensitivity error?

6. What does linearity means in term range of sensor?

7. What does nonlinearity means in term range of sensor?

8. What is a drift?

9. What causes the hysteresis in sensor?

10
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10. What causes the digitization error?

11 What is the dynamic error?

12. What is the sensor resolution?


1. Thermometer is one type of sensor

2. The application of sensor is not much

3. Sensors that measure very small changes must have very high insensitivities

4. Technological progress allows more and more sensors to be manufactured on a

microscopic scale.

5. If the sensitivity is not constant over the range of the sensor, this is called nonlinearity

6. Biological sensors have functions similar to those of the mechanical devices.

7. The resolution is related to the precision of the measurement.

8. Noise is a random error that can be reduced by signal processing

Exercise 3:

- Design a simple sensor, and then describe its working rule

- Summarizing the text of sensor in short paragraph (5-7 lines)

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UNIT 3

ACTUATOR

1. Definition

An actuator is a mechanical device for moving or controlling a mechanism or

system. An actuator typically is a mechanical device that takes energy, usually created by

air, electricity, or liquid, and converts that into some kind of motion. The typical actuator

types are called switches.

A biased switch is one containing

a spring that returns the actuator to a

certain position. The "on-off" notation

can be modified by placing parentheses

around all positions other than the resting

position. For example, an (on)-off-(on)

switch can be switched on by moving the

contact in either

direction away from the centre, but return to the central off position when the contact is

released. The momentary push-button switch is a type of biased switch. The most

common type is a "push-to-make" (or normally-open or NO) switch, which makes contact

when the button is pressed and breaks when the button is released. Each key of a

computer keyboard, for example, is a normally-open "push-to-make" switch. A "push-to-

break" (or normally-closed or NC) switch, on the other hand, breaks contact when the

button is pressed and makes contact when it is released. An example of a push-to-break

switch is a button used to release a door held open by an electromagnet.

2. Some types of Actuator

-Knife switch: Knife switches are unique; the electrical contacts are exposed, mounted

on an insulating plastic or porcelain plate, unlike modern switches in which the

working parts are enclosed in an insulating plastic or rubber housing to protect

users from contact with hazardous voltages. The "knife", a flat metal swinging

arm, is moved by the user between two or more gripping contacts of springy

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Fig. 7 Three pushbutton switches
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metal. The knife and contacts are typically formed of copper, steel, or brass,

depending on the application.

The primary advantage of a knife

switch is the extremely high current

capability inherent to the design. The

amount of surface area on the "knife" that

shorts the contacts is also extremely high,

allowing a wide range of high vol-

tage or high amperage applications with no circuit degradation, choke, or arcing during

switch throw. Thicker components need only be accompanied by wider contacts

to conduct higher currents, which allow the design to scale extremely well with

size. Its disadvantage is that to operate it, a user has to grasp the knife's insulated

handle near the exposed contacts and knife blade, causing a great risk of electric

shock. Although knife switches are inferior to traditional switches in applications

where user safety is paramount, they are still commonly employed in everyday

high-voltage applications such as building transformers, large power relays, and

air-conditioning units.

-An electronic switch: is an electrical component that can break an electrical circuit,

interrupting the current or diverting it from one conductor to another. The most familiar

form of switch is a manually operated electromechanical device with one or more sets of

electrical contacts. Each set of contacts can be in one of two states: either 'closed'

meaning the contacts are touching and electricity can flow between them, or 'open',

meaning the contacts are separated and nonconducting. Since the advent ofdigital logic in

the 1950s, the term has spread to a variety of digital active devices such as transistors and

logic gates whose function is to change their output state between two logic levels or

connect different signal lines, and even computers, network switches, whose function is to

provide connections between differentports in a computer network. The term 'switched' is

also applied to telecommunications networks, and signifies a network that is circuit

switched, providing dedicated circuits for communication between end nodes, such as the

public switched telephone network. The common feature of all these usages is they refer

to devices that control abinarystate: they are eitheron oroff, closedoropen, connected

ornot connected.

13

Fig. 8 The symbol of witches

in diagram
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-Mercury tilt switch:The mercury switch consists of a drop ofmercury inside a glass

bulb with 2 contacts. The two contacts pass through the glass, and are connected

by the mercury when the bulb is tilted to make the mercury roll on to them. This

type of switch performs much better than the ball tilt switch, as the liquid metal

connection is unaffected by dirt, debris and oxidation, it wets the contacts

ensuring a very low resistance bounce-free connection, and movement and

vibration do not produce a poor contact. These types can be used for precision

works. It can also be used where arcing is dangerous (such as in the presence of

explosive vapour) as the entire unit is sealed. A simple semiconductorswitch is a

transistor. Other types of switch include:

1. Centrifugal switch

2. DIP switch

3. Hall-effect switch

4. Inertial switch

5. Membrane switch

6. Toggle switch

7. Transfer switch

8. Time switch

9. Vandal resistant switch

10.Latching switch

3. Contacts

In the simplest case, a switch has two pieces ofmetalcalled contacts that touch to

make a circuit, and separate to break the circuit. The contact material is chosen for its

resistance to corrosion, because most metals form insulatingoxides that would prevent

the switch from working. Contact materials are also chosen on the basis of electrical

conductivity, hardness (resistance to abrasive wear), mechanical strength, low cost and

low toxicity Sometimes the contacts areplated with noble metals. They may be designed

to wipe against each other to clean off any contamination. Nonmetallic conductors, such

as conductiveplastic, are sometimes used.

A pair of contacts is said to be 'closed' when there is no space between them,

allowing electricity to flow from one to the other. When the contacts are separated by an

14
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insulating air gap, an air space, they are said to be 'open', and no electricity can flow at

typical voltages.

Some contacts are normally open (Abbreviated "n.o." or "no") until closed by

operation of the switch, while others are normally closed ("n.c. or "nc") and opened by

the switch action, where the abbreviations given are commonly used on electronics

diagrams for clarity of operation in assembly, analysis or troubleshooting. They serve to

synchronize meaning with possible mistakes in wiring assembly, where wiring part of

switch one way and part another (usually opposite) way will pretty much guarantee things

won't work as designed.


1. What is an actuator?

2. What is the normally close switch?

3. What is the normally open switch?

4. What is the function of knife portion in electric switch?

5. What is knife made of?

6. What are advantages, disadvantages of a knife switch?

7. What is electronic switch?

8. What is a mercury tilt switch?

9. What are the advantages of mercury tilt switch?

10. Where is mercury tilt switches used?

11. What are criterions of chosen material for making switch contact?

12. What is a contact?


1. An on-off switch can be switched on by moving the contact in either direction away

from the centre, but return to the central off position

2. An NC switch makes contact when the button is pressed and breaks when the button is

released

3. The knife and contacts are typically made of copper, steel, or brass, depending on the

application.

4. The knife switches are still employed in high-voltage applications such as building

15
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transformers

5. The mercury tilt switch performs much better than the ball tilt switch

6. A simple semiconductorswitch may be a transistor


UNIT 4

LOGIC GATE

1. Definition

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A logic gate performs a logical operation on one or more logic inputs and produces a

single logic output. The logic normally performed is Boolean logic and is most commonly

found in digital circuits. Logic gates are primarily implemented electronically using

diodes ortransistors, but can also be constructed using electromagnetic relays, fluidics,

optics, molecules, or even mechanicalelements.

In electronic logic, a logic level is represented by a voltage or current, (which

depends on the type of electronic logic in use). Each logic gate requires power so that it

can source and sink currents to achieve the correct output voltage. In logic circuit

diagrams the power is not shown, but in a full electronic schematic, power connections

are required.

A truth table is a table that describes the behavior of a logic gate. It lists the value

of the output for every possible combination of the inputs and can be used to simplify the

number of logic gates and level of nesting in an electronic circuit. In general the truth

table does not lead to an efficient implementation like a minimization procedure, using

Karnaugh maps, the QuineMcCluskey algorithm or a heuristic algorithm is required for

reducing the circuit complexity.

2. Logic family

The simplest form of electronic logic is diode logic. This allows AND and OR

gates to be built, but not inverters, and so is an incomplete form of logic. Further, without

some kind of amplification it is not possible to have such basic logic operations cascaded

as required for more complex logic functions. To build a functionally complete logic

system,relays, valves(vacuum tubes), ortransistors can be used. The simplest family of

logic gates using bipolar transistors is called resistor-transistor logic, or RTL. Unlike

diode logic gates, RTL gates can be cascaded indefinitely to produce more complex logic

functions. These gates were used in early integrated circuits. For higher speed, the

resistors used in RTL were replaced by diodes, leading to diode-transistor logic, or DTL.

It was then discovered that one transistor could do the job of two diodes in the space of

one diode even better, by more quickly switching off the following stage, so transistor-

transistor logic, or TTL, was created. In virtually every type of contemporary chip

implementation of digital systems, the bipolar transistors have been replaced by

complementaryfield-effect transistors (MOSFETs) to reduce size and power consumption

17
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still further, thereby resulting in complementary Metal Oxide Semiconductor (CMOS)

logic.

For small-scale logic, designers now use prefabricated logic gates from families of

devices such as theTTL7400 series byTexas Instruments and the CMOS4000 seriesby

RCA, and their more recent descendants. Increasingly, these fixed-function logic gates

are being replaced byprogrammable logic devices, which allow designers to pack a large

number of mixed logic gates into a single integrated circuit. The field-programmable

nature ofprogrammable logic devices such as FPGAs has removed the 'hard' property of

hardware; it is now possible to change the logic design of a hardware system by

reprogramming some of its components, thus allowing the features or function of a

hardware implementation of a logic system to be changed.

Electronic logic gates differ significantly from their relay-and-switch equivalents.

They are much faster, consume much less power, and are much smaller (all by a factor of

a million or more in most cases). Also, there is a fundamental structural difference. The

switch circuit creates a continuous metallic path for current to flow (in either direction)

between its input and its output. The semiconductor logic gate, on the other hand, acts as

a high-gainvoltageamplifier, which sinks a tiny current at its input and produces a low-

impedance voltage at its output. It is not possible for current to flow between the output

and the input of a semiconductor logic gate.

Another important advantage of standardized integrated circuit logic families,

such as the 7400 and 4000 families, is that they can be cascaded. This means that the

output of one gate can be wired to the inputs of one or several other gates, and so on.

Systems with varying degrees of complexity can be built without great concern of the

designer for the internal workings of the gates. The output of one gate can only drive a

finite number of inputs to other gates, a number called the 'fanout limit'. Also, there is

always a delay, called the 'propagation delay', from a change in input of a gate to the

corresponding change in its output. When gates are cascaded, the total propagation delay

is approximately the sum of the individual delays, an effect which can become a problem

in high-speed circuits. Additional delay can be caused when a large number of inputs are

connected to an output, due to the distributed capacitance of all the inputs and wiring and

the finite amount of current that each output can provide.

3. Types of Logic gates

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NANDandNORlogic gates are the two pillars of logic, in that all other types of

Boolean logic gates (i.e., AND,OR,NOT, XOR,NOR) can

be created from a suitable network of just NAND

or just NOR gate(s). They can be built from

relays or transistors, or any other technology that

can create an inverter and a two-input AND or

OR gate. Hence the NAND and NOR gates are

called the universal gates. For an input of 2

variables, there are 16 possible Boolean algebraic

functions. These 16 functions are enumerated

below, together with their outputs for each

combination of inputs variables.

In the 1980s, schematics were the predominant method to design both circuit

boards and custom ICs known as gate arrays. Today, custom ICs and the field-

programmable gate array are typically designed with Hardware Description Languages

(HDL) such as VerilogorVHDL. The need for complex logic symbols has diminished

and distinctive shape symbols are still the predominate style.

Two more gates are the exclusive-OR or XOR function and its inverse, exclusive-

NOR or XNOR. The two input Exclusive-OR is true only when the two input values are

different, false if they are equal, regardless of the value.

If there are more than two inputs, the gate generates a true at its output if the

number of trues at its input is odd. In practice, these gates are built from combinations of

simpler logic gates. By use ofDe Morgan's theorem, an AND gate can be turned into an

OR gate by inverting the sense

of the logic at its inputs and outputs. This leads to a

separate set of symbols with inverted inputs and the

opposite core symbol.

These symbols can make circuit diagrams

for circuits using active low signals much clearer

and help to show accidental connection of an active

high output to an active low input or vice-versa.

19

Fig. 9 Logic state of two inputs

Fig 10. One chip with four NANDs
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1. What does logic gate perform?

2. What relation between Boolean logic and logic gate?

3. What is the truth table?

4. How are the outputs created in logic gate?

5. Which algorithms are use to reduce degree of logic gate complexity?

6. Which components are used to build complete logic systems?

7. What do the RTL, DTL, TTL stand for?

8. What differences between RTL, DTL and TTL?

9. What is CMOS logic?

10. Why will fix function logic gate be replaced by PLD?

11. What are important features of FPGA?

12. What are the significant difference between logic gate and relay-and switch

equivalents?

13. What major advantages are in 7400 and 4000 families?

14. Why propagation delays happen in logic system?

15. Why are NAND, NOR gates called universal gates?


1. Logic gates are constructed using electromagneticrelays,fluidics,optics,molecules, or

evenmechanical elements.

2. In electronic logic, a logic level is represented only by a voltage

3. The truth table provide the minimization procedures for designing logic system

4. In logic system, the total system delay time is the sum of individual delay time

5. Today, custom ICs are typically designed with VHDL

6. An AND gate can be turned into an OR gate


20
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UNIT 5

NANOELECTRONICS TECHNOLOGY

1. Introduction

Nanoelectronics refer to the use ofnanotechnology on electronic components, especially

transistors. Although the term nanotechnology is generally defined as utilizing technology

less than 100 nm in size, nanoelectronics often refer to transistor devices that are so small

that inter-atomic interactions and quantum mechanical properties need to be studied

extensively. As a result, present transistors (such as recent Intel Core i7 processors from

Intel) do not fall under this category, even though these devices are manufactured under

65 nm or 45 nm technology.

Nanoelectronics are sometimes considered as disruptive technology because

present candidates are significantly different from traditional transistors. Some of these

candidates include: hybrid molecular/semicon-ductor electronics, one dimensional

nanotubes/nanowires, or advanced molecular electronics. The sub-voltage and deep-sub-

voltage nanoelec-tronics are specific and important fields of R&D, and the appearance of

new ICs operating almost near theoretical limit (fundamental, technolog-ical, design

methodological, architectural, algorithmic) on energy consumption per 1 bit processing is

21
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inevitable. The important case of fund-amental ultimate limit for logic operation is

reversible computing.

Although all of these hold immense promises for the future, they are still under

development and will most likely not be used for manufacturing any time soon.

2. Types of nanoelctronic

-Nanofabrication

Nanofabrication can be used to construct ultradense parallel arrays of nano-wires, as an

alternative to synthesizing nanowires individually. For example, single electron

transistors, which involve transistor operation based on a single electron.

Nanoelectromechanical systems also falls under this category.

-Nanomaterials electronics

Besides being small and allowing more transistors to be packed into a single chip, the

uniform and symmetrical structure ofnanotubes allows a higherelectron mobility (faster

electron movement in the material), a higherdielectric constant (faster frequency), and a

symmetrical electr-on/hole characteristic. Also, nanoparticles can be used as quantum

dots.

- Molecular electronics

Single molecule devices are another possibility. These schemes would make heavy use of

molecular self-assembly, designing the device compon-ents to construct a larger structure

or even a complete system on their own. This can be very useful for reconfigurable

computing, and may even completely replace presentFPGA technology.

Molecular electronics is a new technology which is still in its infancy, but also

brings hope for truly atomic scale electronic systems in the future. One of the more

promising applications of molecular electronics was proposed by the IBM researcher Ari

Aviram and the theoretical chemist Mark Ratner in their 1974 and 1988 on papers

Molecules for Memory, Logic and Amplification. This is one of many possible ways in

which a molecular level diode/transistor might be synthesized by organic chemistry. A

model system was proposed with a spiro carbon structure giving a molecular diode about

half a nanometre across which could be connected by polythiophene molecular wires.

Theoretical calculations showed the design to be sound in principle and there is still hope

that such a system can be made to work.

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3. Applications

- Computers

Nanoelectronics holds the promise of makingcomputer processors more powerful than

are possible with conventional semiconductor fabrication techniques. A number of

approaches are currently being researched, inclu-ding new forms ofnanolithography, as

well as the use of nanomaterials such as nanowires or small molecules in place of

traditionalCMOS compo-

ent. Field effect transistorshave been made using

both semiconductingcarbon nanotubes and with

heterostructured semiconductor nanowires.

- Energy production

Research is ongoing to use nanowires and

other nanostructured materials with the hope to

create cheaper and more efficient solar cells than

are possible with conventional planar silicon

solar cells. It is believed that the invention

of more efficient solar energy would have a great effect on satisfying global energy needs.

There is also research into energy production for devices that would operate in

vivo, called bio-nano generators. A bio-nano generator is a nanoscale electrochemical

device, like a fuel cell orgalvanic cell, but drawing power fromblood glucose in a living

body, much the same as how the body generates energyfrom food. To achieve the effect,

anenzyme is used that is capable of stripping glucose of its electrons, freeing them for

use in electrical devices. The average person's body could, theoretically, generate 100

watts ofelectricity (about 2000 food calories per day) using a bio-nano generator.However, this estimate is only true if all food was converted to electricity, and the human

body needs some energy consistently, so possible power generated is likely much lower.

The electricity generated by such a device could power devices embedded in the body

(such aspacemakers), or sugar-fed nanorobots. Much of the research done on bio-nano

generators is still experimental, with Panasonic's Nanotechnology Research Laboratory

among those at the forefront.

- Medical diagnostics

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Fig. 11 The device transfers energyfrom nano-thin layers of

quantum wells to nanocrystals

Fig. 12 Buckminsterfulleren C60

known as the buckyball, is the

simplest of the carbon structure
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There is great interest in constructing

nanoelectronic devices that could detect the

concentrations ofbiomolecules in real time for

use as medical diagnostics, thus falling into the

category ofnanomedicine. A parallel line of

research seeks to create nanoelectronic devices

which could interact with single cells for use in

basic biological research. These

devices are callednanosensors. Such miniaturization on nanoelectronics towards in vivo

proteomic sensing should enable new approaches for health monitoring, surveillance, and

defense technology.


1. What are nanoelectronics technology?

2. Why are nanoelectronics called disruptive technology?

3. What candidates are included in nanoelectronic technology?

4. Which theoretical limit of new ICs?

5. What advantages of small size and transistors packed into single chip?

6. Which application of molecular electronics was proposed by the IBM researcher?

7. Which are the nano materials being researched for computer application?

8. What is a bio-nano generator?

9. How many watts could an average persons body produce in theoretically?

10. What is nanomedicine?

11. What is a nanosensor?

12. Where still take experiences in bio-nano generator?

13. In bio-nano generator, from what electric power is created ?


1. Nanoelectronics refer to the use ofelectronic components like transistors

2. The term is generally defined as technology greater than 100 nm in size

3. Recent Intel Core i7 processors from Intel are one type of device using nanotechnology

4. Transistorsusing nanotechnology can be operated basing on a single electron.

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5. Using nanotechnology makes computer processors more powerful than conventional

semiconductor fabrication techniques

6. Single molecule devices can be very useful forreconfigurable computing, and may

even completely replace presentFPGA technology

Exercise 3:Find more information about new products that using nanotechnology.


UNIT 6

AUTOMATIC CONTROL

1. Definition

Automatic control is the research area and theoretical base for mechanization and

automation, employing methods from mathematicsandengineering. A central concept is

that of the system which is to be controlled, such as a rudder, propeller or an entire

ballistic missile. The systems studied within automatic control are mostly the linear

systems. Automatic control systems are composed of three components:

Sensor(s), which measure some physical state such as temperature or liquid level.

Responder(s), which may be simple electrical or mechanical systems or complex

special purpose digital controllers or general purpose computers.

Actuator(s), which affect a response to the sensor(s) under the command of the

responder, for example, by controlling a gas flow to a burner in a heating system or

electricity to a motor in a refrigerator or pump.

Process control is a statistics and engineering discipline that deals with architectures,

mechanisms, and algorithms for controlling the output of a specificprocess. For example,

heating up the temperature in a room is a process that has the specific, desired outcome to

reach and maintain a defined temperature (e.g. 20C), kept constant over time. Here, the

temperature is the controlled variable. At the same time, it is the inputvariable since it

is measured by a thermometer and used to decide whether to heat or not to heat. The

desired temperature (20C) is the setpoint. The state of the heater (e.g. the setting of the

valve allowing hot water to flow through it) is called the manipulated variable since it is

subject to control actions.

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A commonly used control device called a programmable logic controller, or a

PLC, is used to read a set of digital and analog inputs, apply a set of logic statements, and

generate a set of analog and digital outputs. Using the example in the previous paragraph,

the room temperature would be an input to the PLC. The logical statements would

compare the setpoint to the input temperature and determine whether more or less heating

was necessary to keep the temperature constant. A PLC output would then either open or

close the hot water valve, an incremental amount, depending on whether more or less hot

water was needed. Larger more complex systems can be controlled by a Distributed

Control System (DCS) or Supervisory Control And Data Acquisition (SCADA) system.

In practice, process control systems can be characterized as one or more of the

following forms:

Discrete Found in many manufacturing, motion and packaging applications.

Robotic assembly, such as that found in automotive production, can be characterized as

discrete process control. Most discrete manufacturing involves the production of discrete

pieces of product, such as metal stamping.

Batch Some applications require that specific quantities of raw materials be

combined in specific ways for particular durations to produce an intermediate or end

result. One example is the production of adhesives and glues, which normally require the

mixing of raw materials in a heated vessel for a period of time to form a quantity of end

product. Other important examples are the production of food, beverages and medicine.

Batch processes are generally used to produce a relatively low to intermediate quantity of

product per year (a few pounds to millions of pounds).

Continuous Often, a physical system is represented though variables that are

smooth and uninterrupted in time. The control of the water temperature in a heating

jacket, for example, is an example of continuous process control. Some importantcontinuous processes are the production of fuels, chemicals and plastics. Continuous

processes, in manufacturing, are used to produce very large quantities of product per year

(millions to billions of pounds).

2. Some types of automatic control system.

A thermostat is a simple example for a closed control loop: It constantly measures the

current temperature and controls the heater's valve setting to increase or decrease the

room temperature according to the user-defined setting. A simple method switches the

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heater either completely on, or completely off, and an overshoot and undershoot of the

controlled temperature must be expected. A more expensive method varies the amount of

heat provided by the heater depending on the difference between the required temperature

(the "setpoint") and the actual temperature. This minimizes over/undershoot.

Ananti-lock braking system(ABS): is a more complex example, consisting of multiple

inputs, conditions and outputs.

The PID controller: involving three separate parameters: the proportional, the integral

and derivative values. Theproportionalvalue determines the reaction to the current error,

the integral value determines the reaction based on the sum of recent errors, and the

derivative value determines the reaction based on the rate at which the error has been

changing. The weighted sum of these three actions is used to adjust the process via a

control element such as the position of a control valve or the power supply of a heating

element.

By tuning the three constants in the PID controller algorithm, the controller can

provide control action designed for specific process requirements. The response of the

controller can be described in terms of the responsiveness of the controller to an error, the

degree to which the controller overshoots the setpoint and the degree of system

oscillation. Note that the use of the PID algorithm for control does not guarantee optimal

control of the system or system stability.

Some applications may require using only one or two modes to provide the

appropriate system control. This is achieved by setting the gain of undesired control

outputs to zero. A PID controller will be called a PI, PD, P or I controller in the absence

of the respective control actions. PI controllers are particularly common, since derivative

action is very sensitive to measurement noise, and the absence of an integral value may

prevent the system from reaching its target value due to the control action.Note: Due to the diversity of the field of control theory and application, many

naming conventions for the relevant variables are in common use.

3. Control loop basics

A familiar example of a control loop is the action taken to keep one's shower

water at the ideal temperature, which typically involves the mixing of two process

streams, cold and hot water. The person feels the water to estimate its temperature. Based

on this measurement they perform a control action: use the cold water tap to adjust the

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process. The person would repeat this input-output control loop, adjusting the hot water

flow until the process temperature stabilized at the desired value.

Feeling the water temperature is taking a measurement of the process value or

process variable (PV). The desired temperature is called the setpoint (SP). The output

from the controller and input to the process (the tap position) is called the manipulated

variable (MV). The difference between the measurement and the setpoint is the error (e),

too hot or too cold and by how much.

As a co

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Tieng Anh Chuyen Nghanh