The scientific study and application of the movement of electrons. The field developed out of 19th-c experiments with electricity, which resulted in the invention of thermionic valves and their subsequent replacement by transistors, introduced at Bell Laboratories in 1948. Transistors facilitated the miniaturization of electronic components, as did the silicon chip and the integrated circuit. The social impact of electronics is far-reaching, including the development of television, computerized office systems, video games, personal computers, pacemakers, and spacecraft.
The design and construction of electronic circuits to solve practical problems is an integral technique in the field of electronics engineering and is equally important in hardware design for computer engineering.Overview of electronic systems and circuits
Electronic systems are used to perform a wide variety of tasks. The main uses of electronic circuits are:
The controlling and processing of data.One way of looking at an electronic system is to divide it into 3 parts:
Inputs – Electronic or mechanical sensors (or transducers). Signal processors – These circuits serve to manipulate, interpret and transform inputted signals in order to make them useful for a desired application. Signal processing circuits inside the television extract information from this signal that dictates brightness, colour and sound level.Electronic devices and components
An electronic component is any indivisible electronic building block packaged in a discrete form with two or more connecting leads or metallic pads. Components are intended to be connected together, usually by soldering to a printed circuit board, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly (resistor, capacitor, transistor, diode etc.) or in more or less complex groups as integrated circuits (operational amplifier, resistor array, logic gate etc).
Types of circuits
Analog circuits
Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits. The number of different analog circuits so far devised is huge, especially because a 'circuit' can be defined as anything from a single component, to systems containing thousands of components.
Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits such as mixers, modulators etc. Good examples of analog circuits include vacuum tube and transistor amplifiers, operational amplifiers and oscillators.
Some analog circuitry these days may use digital or even microprocessor techniques to improve upon the basic performance of the circuit.
Sometimes it may be difficult to differentiate between analog and digital circuits as they have elements of both linear and non-linear operation. An example is the comparator which takes in a continuous range of voltage but puts out only one of two levels as in a digital circuit.
Digital circuits
Digital circuits are electric circuits based on a number of discrete voltage levels. Digital circuits are the most common physical representation of Boolean algebra and are the basis of all digital computers. To most engineers, the terms "digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits.
Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits.
Building-blocks:
logic gates Adders Binary Multipliers flip-flops counters registers multiplexers Schmitt triggersHighly integrated devices:
microprocessors microcontrollers Application specific integrated circuit(ASIC) Digital signal processor (DSP) Field Programmable Gate Array (FPGA)Mixed-signal circuits
Mixed-signal circuits refers to integrated circuits (ICs) which have both analog circuits and digital circuits combined on a single semiconductor die or on the same circuit board. Mixed circuits contain both analog and digital components.
Noise
Noise is associated with all electronic circuits. Noise is generally defined as any unwanted signal that is not present at the input of a circuit. Noise is not the same as signal distortion caused by a circuit. To become proficient in electronics it is also necessary to become proficient in the mathematics of circuit analysis.
Circuit analysis is the study of methods of solving generally linear systems for unknown variables such as the voltage at a certain node or the current though a certain branch of a network.
Electronic test equipment
Electronic test equipment is used to create stimulus signals and capture responses from electronic Devices Under Test (DUTs).
Practical electronics engineering and assembly requires the use of many different kinds of electronic test equipment ranging from the very simple and inexpensive (such as a test light consisting of just a light bulb and a test lead) to extremely complex and sophisticated such as Automatic Test Equipment.
Computer aided design (CAD)
Today's electronics engineers have the ability to design circuits using premanufactured building blocks such as power supplies, resistors, capacitors, semiconductors (such as transistors), and integrated circuits. Electronic design automation software programs include schematic capture programs such as EWB ( electronic work bench )or ORCAD or Eagle Layout Editor, used to make circuit diagrams and printed circuit board layouts. Most modern day electronics now use printed circuit boards or highly integrated circuits.
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