Electronic engineering
From Wikipedia, the free encyclopedia
Electronic engineering is a professional discipline that deals with the behavior and effects of electrons (as in electron tubes and transistors) and with electronic devices, systems, or equipment. The term now also covers a large part of electrical engineering degree courses as studied at most European universities. Its practitioners are called electronics engineers in Europe. In the Americas and some other parts of the world, the term electrical engineer is used to describe a person doing the same work.
In many areas, electronic engineering is considered to be at the same level as electrical engineering, requiring that more general programmes be called electrical and electronic engineering (many UK universities have departments of Electronic and Electrical Engineering). Both define a broad field that encompasses many subfields including those that deal with power, instrumentation engineering, telecommunications, and semiconductor circuit design amongst many others.
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[edit] Terminology
The name electrical engineering is still used to cover electronic engineering amongst some of the older (notably American) universities and graduates there are called electrical engineers. In Europe, graduates of electronic engineering are known as electronics engineers.
Some people believe the term electrical engineer should be reserved for those having specialised in power and heavy current or high voltage engineering, while others believe that power is just one subset of electrical engineering (and indeed the term power engineering is used in that industry). Again, in recent years there has been a growth of new separate-entry degree courses such as information and communication engineering, often followed by academic departments of similar name.
[edit] History of electronic engineering
The modern discipline of electronic engineering was to a large extent born out of radio and television development and from the large amount of Second World War development of defence systems and weapons. In the interwar years, the subject was known as radio engineering and it was only in the late 1950s that the term electronic engineering started to emerge.
In the UK, the subject of electronic engineering became distinct from electrical engineering as a university degree subject around 1960. Students of electronics and related subjects like radio and telecommunications before this time had to enroll in the electrical engineering department of the university as no university had departments of electronics. Electrical engineering was the nearest subject with which electronic engineering could be aligned, although the similarities in subjects covered (except mathematics and electromagnetism) lasted only for the first year of the three-year course.
[edit] Early electronics
In 1893, Nikola Tesla made the first public demonstration of radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of radio communication. In 1896, Guglielmo Marconi made a wireless radio transmission and went on to develop a practical and widely used radio system. In 1904, John Ambrose Fleming , the first professor of electrical Engineering at University College London, invented the first radio tube, the diode. One year later, in 1906, Robert von Lieben and Lee De Forest independently developed the amplifier tube, called the triode.
Electronics is often considered to have begun when Lee De Forest invented the vacuum tube in 1907. Within 10 years, his device was used in radio transmitters and receivers as well as systems for long distance telephone calls. Vacuum tubes remained the preferred amplifying device for 40 years, until researchers working for William Shockley at Bell Labs invented the transistor in 1947. In the following years, transistors made small portable radios, or transistor radios, possible as well as allowing more powerful mainframe computers to be built. Transistors were smaller and required lower voltages than vacuum tubes to work.
In the interwar years the subject of electronics was dominated by the worldwide interest in radio and to some extent telephone and telegraph communications. The terms 'wireless' and 'radio' were then used to refer anything electronic. There were indeed few non-military applications of electronics beyond radio at that time until the advent of television. The subject was not even offered as a separate university degree subject until about 1960.
Prior to the second world war, the subject was commonly known as 'radio engineering' and basically was restricted to aspects of communications and RADAR, commercial radio and early television. At this time, study of radio engineering at universities could only be undertaken as part of a physics degree.
Later, in post war years, as consumer devices began to be developed, the field broadened to include modern TV, audio systems, Hi-Fi and latterly computers and microprocessors. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronic engineering, which then became a stand alone university degree subject, usually taught alongside electrical engineering with which it had become associated due to some similarities.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by hand. These non-integrated circuits consumed much space and power, were prone to failure and were limited in speed although they are still common in simple applications. By contrast, integrated circuits packed a large number — often millions — of tiny electrical components, mainly transistors, into a small chip around the size of a coin. This allowed for the powerful computers and other electrical devices we see today.
[edit] Tubes or valves
[edit] The vacuum tube detector
The invention of the triode amplifier, generator, and detector enabled audio radio. On Christmas Eve, 1906, Reginald Fessenden (using his heterodyne principle) transmitted the first radio audio broadcast in history from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. The first known radio news program was broadcast 31 August 1920 by station 8MK, the unlicensed predecessor of WWJ (AM) in Detroit, Michigan. Regular wireless broadcasts for entertainment commenced in 1922 from the Marconi Research Centre at Writtle near Chelmsford, England.
While some early radios used some type of amplification through electric current or battery, through the mid 1920s the most common type of receiver was the crystal set. In the 1920s, amplifying vacuum tubes revolutionized both radio receivers and transmitters.
[edit] Phonographs and radiogrammes
This is the early name for record players or combined radios and record players that had some presence in the inter war years.
[edit] Television
In 1931 Manfred von Ardenne introduced the cathode ray tube and thus the electronic television. In the same year, the first successful transatlantic television transmission was made from London to New York. The broadcast television system adopted by the BBC in the UK was the EMI system which was chosen over the inferior mechanical system of John Logie Baird.
[edit] Radar and radio location
During WW2 many efforts were expended in the electronic location of enemy targets and aircraft. These included radio beam guidance of bombers, electronic counter measures, early radar systems etc. During this time very little if any effort was expended on consumer electronics developments.
[edit] Computers
In 1942, Konrad Zuse presented the Z3, the world's first functional computer. In 1946, the ENIAC (Electronic Numerical Integrator and Computer) of John Presper Eckert and John Mauchly followed, beginning the computing era. The arithmetic performance of these machines allowed engineers to develop completely new technologies and achieve new objectives. Early examples include the Apollo missions and the NASA moon landing.
[edit] Transistors
The invention of the transistor in 1947 by William B. Shockley, John Bardeen and Walter Brattain opened the door for more compact devices and led to the development of the integrated circuit in 1959 by Jack Kilby.
[edit] Microprocessors
In 1968, Marcian Hoff invented the microprocessor at Intel and thus ignited the development of the personal computer. Hoff's invention was part of an order by a Japanese company for a desktop computer, which Hoff wanted to build as cheaply as possible. The first realization of the microprocessor was the Intel 4004, a 4-bit processor, in 1969, but only in 1973 did the Intel 8080, an 8-bit processor, make the building of the first personal computer, the Altair 8800, possible.
[edit] Electronics
In the field of electronic engineering, engineers design and test circuits that use the electromagnetic properties of electrical components such as resistors, capacitors, inductors, diodes and transistors to achieve a particular functionality. The tuner circuit, which allows the user of a radio to filter out all but a single station, is just one example of such a circuit.
In designing an integrated circuit, electronics engineers first construct circuit schematics that specify the electrical components and describe the interconnections between them. When completed, VLSI engineers convert the schematics into actual layouts, which map the layers of various conductor and semiconductor materials needed to construct the circuit. The conversion from schematics to layouts can be done by software (see electronic design automation) but very often requires human fine-tuning to decrease space and power consumption. Once the layout is complete, it can be sent to a fabrication plant for manufacturing.
Integrated circuits and other electrical components can then be assembled on printed circuit boards to form more complicated circuits. Today, printed circuit boards are found in most electronic devices including televisions, computers and audio players.
[edit] Typical electronic engineering undergraduate syllabus
Apart from electromagnetics and network theory, other items in the syllabus are particular to electronics engineering course. Electrical engineering courses have other specialisms such as machines, power generation and distribution. Note that the following list does not include the large quantity of mathematics (maybe apart from the final year) included in each year's study.
[edit] Electromagnetics
Elements of vector calculus: divergence and curl; Gauss' and Stokes' theorems, Maxwell's equations: differential and integral forms. Wave equation, Poynting vector. Plane waves: propagation through various media; reflection and refraction; phase and group velocity; skin depth. Transmission lines: characteristic impedance; impedance transformation; Smith chart; impedance matching; pulse excitation. Waveguides: modes in rectangular waveguides; boundary conditions; cut-off frequencies; dispersion relations. Antennas: Dipole antennas; antenna arrays; radiation pattern; reciprocity theorem, antenna gain.
[edit] Network theory
Network graphs: matrices associated with graphs; incidence, fundamental cut set and fundamental circuit matrices. Solution methods: nodal and mesh analysis. Network theorems: superposition, Thevenin and Norton's maximum power transfer, Wye-Delta transformation. Steady state sinusoidal analysis using phasors. Linear constant coefficient differential equations; time domain analysis of simple RLC circuits, Solution of network equations using Laplace transform: frequency domain analysis of RLC circuits. 2-port network parameters: driving point and transfer functions. State equations for networks.
[edit] Electronic devices and circuits
Electronic Devices: Energy bands in silicon, intrinsic and extrinsic silicon. Carrier transport in silicon: diffusion current, drift current, mobility, resistivity. Generation and recombination of carriers. p-n junction diode, Zener diode, tunnel diode, BJT, JFET, MOS capacitor, MOSFET, LED, p-I-n and avalanche photo diode, LASERs. Device technology: integrated circuits fabrication process, oxidation, diffusion, ion implantation, photolithography, n-tub, p-tub and twin-tub CMOS process.
Analog Circuits: Equivalent circuits (large and small-signal) of diodes, BJTs, JFETs, and MOSFETs. Simple diode circuits, clipping, clamping, rectifier. Biasing and bias stability of transistor and FET amplifiers. Amplifiers: single-and multi-stage, differential, operational, feedback and power. Analysis of amplifiers; frequency response of amplifiers. Simple op-amp circuits. Filters. Sinusoidal oscillators; criterion for oscillation; single-transistor and op-amp configurations. Function generators and wave-shaping circuits. Power supplies.
Digital circuits: Boolean algebra, minimization of Boolean functions; logic gates digital IC families (DTL, TTL, ECL, MOS, CMOS). Combinational circuits: arithmetic circuits, code converters, multiplexers and decoders. Sequential circuits: latches and flip-flops, counters and shift-registers. Sample and hold circuits, ADCs, DACs. Semiconductor memories. Microprocessor(8085): architecture, programming, memory and I/O interfacing.
[edit] Signals and systems
Definitions and properties of Laplace transform, continuous-time and discrete-time Fourier series, continuous-time and discrete-time Fourier Transform, z-transform. Sampling theorems. Linear Time-Invariant (LTI) Systems: definitions and properties; casuality, stability, impulse response, convolution, poles and zeros frequency response, group delay, phase delay. Signal transmission through LTI systems. Random signals and noise: probability, random variables, probability density function, autocorrelation, power spectral density.
[edit] Control systems
Basic control system components; block diagrammatic description, reduction of block diagrams. Open loop and closed loop (feedback) systems and stability analysis of these systems. Signal flow graphs and their use in determining transfer functions of systems; transient and steady state analysis of LTI control systems and frequency response. Tools and techniques for LTI control system analysis: root loci, Routh-Hurwitz criterion, Bode and Nyquist plots. Control system compensators: elements of lead and lag compensation, elements of Proportional-Integral-Derivative (PID) control. State variable representation and solution of state equation of LTI control systems.
[edit] Communications
Analog communication systems: amplitude and angle modulation and demodulation systems, spectral analysis of these operations, superheterodyne receivers; elements of hardware, realizations of analog communication systems; signal-to-noise ratio (SNR) calculations for amplitude modulation (AM) and frequency modulation (FM) for low noise conditions. Digital communication systems: pulse code modulation (PCM), differential pulse code modulation (DPCM), delta modulation (DM); digital modulation schemes-amplitude, phase and frequency shift keying schemes (ASK, PSK, FSK), matched filter receivers, bandwidth consideration and probability of error calculations for these schemes.
[edit] Education and training
Electronics engineers typically possess an academic degree with a major in electronic engineering. The length of study for such a degree is usually three or four years and the completed degree may be designated as a Bachelor of Engineering, Bachelor of Science or Bachelor of Applied Science depending upon the university.
The degree generally includes units covering physics, mathematics, project management and specific topics in electrical engineering. Initially such topics cover most, if not all, of the subfields of electronic engineering. Students then choose to specialize in one or more subfields towards the end of the degree.
Some electronics engineers also choose to pursue a postgraduate degree such as a Master of Engineering, a Doctor of Philosophy in Engineering or an Engineer's degree. The Master degree is being introduced in some European and American Universities as a first degree and the differentiation of an engineer with graduate and postgraduate studies is often difficult. In these cases, experience is taken into account. The Master and Engineer's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy consists of a significant research component and is often viewed as the entry point to academia.
In most countries, a Bachelor's degree in engineering represents the first step towards certification and the degree program itself is certified by a professional body. After completing a certified degree program the engineer must satisfy a range of requirements (including work experience requirements) before being certified. Once certified the engineer is designated the title of Professional Engineer (in the United States and Canada), Chartered Engineer (in the United Kingdom, Ireland, India, South Africa and Zimbabwe), Chartered Professional Engineer (in Australia) or European Engineer (in much of the European Union).
Fundamental to the discipline are the sciences of physics and mathematics as these help to obtain both a qualitative and quantitative description of how such systems will work. Today most engineering work involves the use of computers and it is commonplace to use computer-aided design programs when designing electronic systems. Although most electronic engineers will understand basic circuit theory, the theories employed by engineers generally depend upon the work they do. For example, quantum mechanics and solid state physics might be relevant to an engineer working on VLSI but are largely irrelevant to engineers working with macroscopic electrical systems.
[edit] Licensure, certification, and regulation
Some locations require a license for one to legally be called an electronics engineer, or an engineer in general. For example, in the United States and Canada "only a licensed engineer may seal engineering work for public and private clients". [2] This requirement is enforced by state and provincial legislation such as Quebec's Engineers Act. [3] In other countries, such as Australia, no such legislation exists. Practically all certifying bodies maintain a code of ethics that they expect all members to abide by or risk expulsion. [4] In this way these organizations play an important role in maintaining ethical standards for the profession. Even in jurisdictions where licenses are not required, engineers are subject to the law. For example, much engineering work is done by contract and is therefore covered by contract law. In cases where an engineer's work fails he or she may be subject to the tort of negligence and, in extreme cases, the charge of criminal negligence. [5] An engineer's work must also comply with numerous other rules and regulations such as building codes and legislation pertaining to environmental law.
In locations where licenses are not required, professional certification may be advantageous.
[edit] Professional bodies
Professional bodies of note for electrical engineers include the Institute of Electrical and Electronics Engineers (IEEE) and the Institution of Electrical Engineers (IEE). The IEEE claims to produce 30 percent of the world's literature in electrical/electronic engineering, has over 360,000 members worldwide and holds over 300 conferences annually. [6] The IEE publishes 14 journals, has a worldwide membership of 120,000, certifies Chartered Engineers in the United Kingdom and claims to be the largest professional engineering society in Europe. [7] [8]
[edit] Modern electronic engineering
Electronic engineering in Europe is a very broad field that encompasses many subfields including those that deal with, electronic devices and circuit design, control systems, electronics and telecommunications, computer systems, embedded software etc. Many European universities now have departments of Electronics that are completely separate from or have completely replaced their electrical engineering departments.
[edit] Subfields
Electronics engineering has many subfields. This section describes some of the most popular subfields in electronic engineering. Although there are engineers who focus exclusively on one subfield, there are also many who focus on a combination of subfields. For more information on each of the following, click the read more... link.
[edit] Overview of electronic engineering
Electronic engineering involves the design and testing of electronic circuits that use the electronic properties of components such as resistors, capacitors, inductors, diodes and transistors to achieve a particular functionality.
Signal processing deals with the analysis and manipulation of signals. Signals can be either analogue, in which case the signal varies continuously according to the information, or digital, in which case the signal varies according to a series of discrete values representing the information.
For analog signals, signal processing may involve the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications. For digital signals, signal processing may involve the compression, error checking and error detection of digital signals.
Telecommunications engineering deals with the transmission of information across a channel such as a co-axial cable, optical fibre or free space.
Transmissions across free space require information to be encoded in a carrier wave in order to shift the information to a carrier frequency suitable for transmission, this is known as modulation. Popular analog modulation techniques include amplitude modulation and frequency modulation. The choice of modulation affects the cost and performance of a system and these two factors must be balanced carefully by the engineer.
Once the transmission characteristics of a system are determined, telecommunication engineers design the transmitters and receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a transceiver. A key consideration in the design of transmitters is their power consumption as this is closely related to their signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by noise.
Control engineering has a wide range of applications from the flight and propulsion systems of commercial aeroplanes to the cruise control present in many modern cars. It also plays an important role in industrial automation.
Control engineers often utilize feedback when designing control systems. For example, in a car with cruise control the vehicle's speed is continuously monitored and fed back to the system which adjusts the engine's speed accordingly. Where there is regular feedback, control theory can be used to determine how the system responds to such feedback. Read more...
Instrumentation engineering deals with the design of devices to measure physical quantities such as pressure, flow and temperature. These devices are known as instrumentation.
The design of such instrumentation requires a good understanding of physics that often extends beyond electromagnetic theory. For example, radar guns use the Doppler effect to measure the speed of oncoming vehicles. Similarly, thermocouples use the Peltier-Seebeck effect to measure the temperature difference between two points.
Often instrumentation is not used by itself, but instead as the sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering. Read more...
Computer engineering deals with the design of computers and computer systems. This may involve the design of new hardware, the design of PDAs or the use of computers to control an industrial plant. Computer engineers may also work on a system's software. However, the design of complex software systems is often the domain of software engineering, which is usually considered a separate discipline.
Desktop computers represent a tiny fraction of the devices a computer engineer might work on, as computer-like architectures are now found in a range of devices including video game consoles and DVD players. Read more...
[edit] Project engineering
For most engineers not involved at the cutting edge of system design and development, technical work accounts for only a fraction of the work they do. A lot of time is also spent on tasks such as discussing proposals with clients, preparing budgets and determining project schedules. Many senior engineers manage a team of technicians or other engineers and for this reason project management skills are important. Most engineering projects involve some form of documentation and strong written communication skills are therefore very important.
The workplaces of electronics engineers are just as varied as the types of work they do. Electronics engineers may be found in the pristine laboratory environment of a fabrication plant, the offices of a consulting firm or in a research laboratory. During their working life, electronics engineers may find themselves supervising a wide range of individuals including scientists, electricians, computer programmers and other engineers.
Obsolescence of technical skills is a serious concern for electronics engineers. Membership and participation in technical societies, regular reviews of periodicals in the field and a habit of continued learning are therefore essential to maintaining proficiency. And these are mostly used in the field of consumer electronics products
[edit] See also
- Electronics
- History of radio
- Radio
- List of electrical engineering topics (alphabetical)
- List of electrical engineers
