The study of new semiconductor devices and related technologies is sometimes considered as a branch of physics. This article focuses on the engineering aspects of electronics.
Electronic systems are used to perform various tasks. The main uses of electronic circuits are:
Control and processing of data.
Conversion and distribution of electric power.
Both applications involve the generation and/or detection of electromagnetic fields and currents. Although electric energy had been used to transmit data by telegraph and telephone line before the late19th century, the development of electronics increased exponentially after the appearance of radio.
One way to look at an electronic system is to divide it into three parts:
Input–Electronic or mechanical sensor (or transducer). These devices acquire signals/information from external sources in the physical world (such as antennas or technical networks) and convert these signals/information into current/voltage or digital (high/low) signals in the system.
Signal processors-These circuits are used to process, interpret and convert input signals to make them suitable for the required applications. Recently, with the use of digital signal processors, complex signal processing has been completed.
Output–an actuator or other device (such as a sensor) that converts a current/voltage signal back to a useful physical form (for example, by performing a physical task, such as rotating a motor).
For example, a TV set contains these three parts. The input of TV converts broadcast signals (received through antenna or input through cable) into current/voltage signals that can be used by equipment. The signal processing circuit inside the TV extracts information from this signal, indicating brightness, color and sound level. Then, the output device converts this information back to physical form. Cathode ray tubes convert electronic signals into visible images on the screen. A speaker driven by a magnet converts the signal into audible sound.
Electronic equipment and components
An electronic component is any physical entity in an electronic system, and its purpose is to influence electrons or their related fields in an expected way that conforms to the expected function of the electronic system. Components are usually intended to be in electromechanical contact with each other, and electronic circuits (such as amplifiers, radio receivers or oscillators) with specific functions are usually created by soldering to a printed circuit board (PCB). Components can be packaged individually or in more or less complex groups as integrated circuits.
Circuit type
artificial circuit
Most analog electronic devices, such as radios, are composed of several basic circuits. Analog circuits use a continuous voltage range instead of discrete levels in digital circuits. So far, the number of different analog circuits designed is enormous, especially because "circuit" can be defined as anything from a single element to a system containing thousands of elements.
Analog circuits are sometimes called linear circuits, although many nonlinear effects are used in analog circuits, such as mixers and modulators. Good examples of analog circuits include vacuum tubes and transistor amplifiers, operational amplifiers and oscillators.
Nowadays, some analog circuits may use digital or even microprocessor technology to improve the basic performance of the circuit. This kind of circuit is usually called "mixed signal"
It may sometimes be difficult to distinguish between analog and digital circuits because they have both linear and nonlinear operating elements. An example is a comparator, which receives a continuous voltage range but outputs only one of two levels, just like in a digital circuit. Similarly, an overdriven transistor amplifier can have the characteristics of controlled switching, basically having two output levels.
digital circuit
Main article: Digital circuit
Digital circuits are circuits based on many discrete voltage levels. Digital circuit is the most common physical representation of Bo Olian algebra and the foundation of all digital computers. For most engineers, the terms "digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits. In most cases, the number of different states of a node is two, which are represented by two voltage levels marked as "low" (0) and "high" (1). Usually "low" will be close to zero volts, while "high" will be at a higher level, depending on the power supply voltage used.
Computers, electronic clocks and programmable logic controllers (used to control industrial processes) are all made up of digital circuits. A digital signal processor is another example.
Building blocks:
Logic gate
adder
Binary multiplier
Flip-flops
counter
register
Multiplexer
Schmitt trigger
Highly integrated devices:
micro processor
microcontroller
asic
Digital signal processor (DSP)
Field programmable gate array (FPGA)
Mixed signal circuit
Main article: mixed signal integrated circuit
Mixed-signal circuit refers to integrated circuit (ICs), which combines analog circuit and digital circuit on a semiconductor chip or the same circuit board. Mixed-signal circuits are becoming more and more common. Hybrid circuits are usually used to control the speed of analog devices using digital logic, such as motors. Analog-to-digital converters and digital-to-analog converters are the main examples. Other examples are transmission gates and buffers.
Heat dissipation and thermal management
Main article: Thermal management of electronic equipment and systems.
Heat generated by electronic circuits must be dissipated to prevent immediate failure and improve long-term reliability. Heat dissipation technology can include radiators and fans for air cooling, as well as other forms of computer cooling, such as water cooling. These techniques use convection, conduction and. Thermal radiation.
noise
Main article: Electronic noise
All electronic circuits are noisy. The definition of noise [1] is the interference superimposed on the useful signal, which will blur the information content of the useful signal. Noise is different from signal distortion caused by circuit.
Electronic theory
Main article: Mathematical methods in electronics.
Mathematical method is an indispensable part of electronics research. In order to master electronics, it is also necessary to master the mathematics of circuit analysis.
Circuit analysis is a method to solve general linear systems with unknown variables, such as the voltage at a node or the current through a branch of the network. SPICE circuit simulator is a common analysis tool.
It is also important for electronics to learn and understand the electromagnetic field theory.
electronic test equipment
Main article: electronic test equipment
Electronic test equipment is used to generate excitation signals and capture the response of the electronic device under test (dut). In this way, the normal operation of the automatic DUT can be proved, or the faults in the equipment can be tracked and repaired.
The actual electronic engineering and assembly need to use many different kinds of electronic test equipment, ranging from very simple and expensive (such as a test lamp consisting only of light bulbs and test leads) to very complicated and complicated, such as automatic test equipment.
Computer aided design
Main article: Electronic design automation
Today's electronic engineers have the ability to design circuits using prefabricated components, such as power supplies, semiconductors (such as transistors) and integrated circuits. Electronic design automation software program includes schematic diagram capture program and printed circuit board design program. Popular names in EDA software field include NI Multisim, Cadence (ORCAD), Eagle PCB and schematic diagram, Mentor (PADS PCB and LOGIC schematic diagram), Altium (Protel), LabCentre Electronics (Proteus) and so on.
Construction method
Main article: electronic packaging
Over the years, many different methods of connecting parts have been used. For example, early electronic equipment usually used point-to-point wiring to connect components to wooden test boards to build circuits. Other methods used are wooden building and wire winding. Most modern electronic products now use printed circuit boards (made of FR4) and highly integrated circuits. With the Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) which came into effect in July 2006, in recent years, health and environmental problems related to electronic assembly have attracted more and more attention, especially for products shipped to the European Union.