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{{short description|Electronic systems with a continuously variable signal}}
{{Mergefrom|Analog device|date=June 2007}}
{{Use Oxford spelling|date=August 2016}}
⚫ '''Analog electronics''' (or "analogue", see ]) are those ] systems with a ] ] signal. In contrast, in ] signals usually take only two different levels. The term "analog" describes the proportional relationship between a signal and a voltage or current that represented the signal.
⚫ == Analog signals ==
{{main|Analog signal}}


{{image frame
An analog signal uses some property of the medium to convey the signal's information. For example, an ] ] uses ] position as the signal to convey ] information. Electrical signals may represent information by changing their voltage, current, frequency, or total charge. Information is converted from some other physical form ( such as sound, light, temperature, pressure, position) to an electrical signal by a ].
|content=]]
|caption=Analogue electronic components like this ] function with ] signals, unlike ] which have ], usually ]
|width=200}}


⚫ '''Analogue electronics''' ({{langx|en-US|'''analog electronics'''}}) are ] systems with a ] variable signal, in contrast to ] where signals usually take ]. The term ''analogue'' describes the proportional relationship between a signal and a voltage or current that represents the signal. The word ''analogue'' is derived from the Greek word {{lang|grc|ανάλογος}} {{lang|grc-Latn|analogos}} meaning ''proportional''.<ref>{{cite book |title=Concise Oxford dictionary |publisher=Oxford University Press Inc. |year=1999 |isbn=0-19-860287-1 |edition=10}}</ref>
⚫ The signals take any value from a given range, and each unique signal value represents different information. Any change in the signal is meaningful, and each level of the signal represents a different level of the phenomenon that it represents. For example, suppose the signal is being used to represent temperature, with one ] representing one degree ]. In such a system 10 volts would represent 10 degrees, and 10.1 volts would represent 10.1 degrees.


⚫ == Analogue signals ==
⚫ Another method of conveying an analog signal is to use ]. In this, some base carrier signal has one of its properties altered: ] (AM) involves altering the amplitude of a sinusoidal voltage waveform by the source information, ] (FM) changes the frequency. Other techniques, such as changing the phase of the carrier signal are also used.
An ] uses some attribute of the medium to convey the signal's information. For example, an ] uses the ] of a needle on top of a contracting and expanding box as the signal to convey the information of changes in ].<ref>{{cite book |last=Plympton |first=George Washington |title=The aneroid barometer: its construction and use |year=1884 |publisher=D. Van Nostran Co. |url=https://archive.org/details/aneroidbaromete00plymgoog |quote=aneroid barometer. }}</ref> Electrical signals may represent information by changing their ], ], ], or total ]. Information is converted from some other physical form (such as ], ], ], ], position) to an electrical signal by a ] which converts one type of energy into another (e.g. a ]).<ref>{{cite book |last=Singmin |first=Andrew |title=Beginning Digital Electronics Through Projects |url=https://books.google.com/books?id=av_37zMG5H4C&q=analogue+electronics+transducer&pg=PA9 |page=9 |year=2001 |publisher=Newnes |isbn=0-7506-7269-2 |quote=Signals come from transducers...}}</ref>


⚫ The signals take any value from a given range, and each unique signal value represents different information. Any change in the signal is meaningful, and each level of the signal represents a different level of the phenomenon that it represents. For example, suppose the signal is being used to represent temperature, with one ] representing one degree ]. In such a system, 10 volts would represent 10 degrees, and 10.1 volts would represent 10.1 degrees.
⚫ In an analog sound recording, the variation in pressure of a sound striking a ] creates a corresponding variation in the current passing through it or voltage across it. An increase in the volume of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same ] or shape.


⚫ Another method of conveying an analogue signal is to use ]. In this, some base ] has one of its properties altered: ] (AM) involves altering the amplitude of a sinusoidal voltage waveform by the source information, ] (FM) changes the frequency. Other techniques, such as ] or changing the phase of the carrier signal, are also used.<ref>{{cite book |last=Miller |first=Mark R. |title=Electronics the Easy Way |url=https://archive.org/details/electronicseasyw0004mill |url-access=registration |pages=–239 |year=2002 |publisher=Barron's Educational Series |isbn=0-7641-1981-8 |quote=Until the radio came along...}}</ref>
⚫ ], ], ] and other systems may also use analog signals.


⚫ In an analogue sound recording, the variation in pressure of a sound striking a ] creates a corresponding variation in the current passing through it or voltage across it. An increase in the volume of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same ] or shape.
⚫ ==Inherent noise==
Analog systems exhibit ]; that is, random disturbances or variations. Since all variations of an analog signal are significant, any disturbance is equivalent to a change in the original signal and so appears as noise. As the signal is copied and re-copied, or transmitted over long distances, these random variations become dominant and lead to signal degradation. Electrically these disturbances are reduced by ], and using low noise amplifiers.


⚫ ], ], ], and other systems may also use analogue signals.
The effects of random noise can make signal loss and distortion impossible to recover, since amplifying the signal to recover attenuated parts of the signal often generates more noise and amplifies the noise as well.


⚫ == Inherent noise ==
⚫ == Analog vs. digital electronics==
Analogue systems invariably include ] that is random disturbances or variations, some caused by the ] of atomic particles. Since all variations of an analogue signal are significant, any disturbance is equivalent to a change in the original signal and so appears as noise.<ref>{{cite book |last=Hsu |first=Hwei Piao |title=Schaum's Outline of Theory and Problems of Analogue and Digital Communications |url=https://books.google.com/books?id=02I-J_ZQa50C&q=analogue+system+noise&pg=PA202 |page=202 |year=2003 |publisher=McGraw-Hill Professional |isbn=0-07-140228-4 |quote=The presence of noise degrades the performance of communication systems. }}</ref> As the signal is copied and re-copied, or transmitted over long distances, these random variations become more significant and lead to ]. Other sources of noise may include ] from other signals or poorly designed components. These disturbances are reduced by ] and by using ]s (LNA).<ref>{{cite book |last=Carr |first=Joseph J. |title=Secrets of RF circuit design |url=https://books.google.com/books?id=begI88-yUBwC&q=low+noise+amplifiers&pg=PA423 |page=423 |year=2000 |publisher=McGraw-Hill Professional |isbn=0-07-137067-6 |quote=It is common in microwave systems...}}</ref>
⚫ Since the information is encoded differently in analog and ], the way they process a signal is consequently different. All operations that can be performed on an analog signal such as ], ], limiting, and others, can also be duplicated in the digital domain.


⚫ ==Analogue vs digital electronics==
The first electronic devices invented and ] were analog. The use of ] has reduced the cost of digital techniques and now make digital methods feasible and cost-effective.


] is inherently an analogue signal]]
The main differences between analog and digital electronics are listed below:


⚫ Since the information is encoded differently in analogue and ], the way they process a signal is consequently different. All operations that can be performed on an analogue signal such as ], ], limiting, and others, can also be duplicated in the digital domain. Every digital circuit is also an analogue circuit, in that the behaviour of any digital circuit can be explained using the rules of analogue circuits.
;Noise : Because of the way information is encoded in analog circuits, they are much more susceptible to ] than digital circuits, since a small change in the signal can represent a significant change in the information present in the signal and can cause the information present to be lost. Since digital signals take on one of only two different values, a disturbance would have to be about one-half the magnitude of the digital signal to cause an error; this property of digital circuits can be exploited to make ] noise-resistant. In digital electronics, because the information is ], as long as the signal stays inside a range of values, it represents the same information. Digital circuits use this principle to regenerate the signal at each ], lessening or removing noise.


The use of ] has made digital devices cheap and widely available.
;Precision : A number of factors affect how precise a signal is, mainly the noise present in the original signal and the noise added by processing. See ]. Fundamental physical limits such as the ] in components limits the resolution of analog signals. In digital electronics additional precision is obtained by using additional digits to represent the signal; the practical limit in the number of digits is determined by the performance of the ], since digital operations can usually be performed without loss of precision.


===Noise===
;Design Difficulty : Digital systems are much easier and smaller to design than comparable analog circuits. This is one of the main reasons why digital systems are more common than analog. An analog circuit must be designed by hand, and the process is much less automated than for digital systems. Also, because the smaller the ] (chip) the cheaper it is, and digital systems are much smaller than analog, digital is cheaper to manufacture.


The effect of ] on an analogue circuit is a function of the ] of noise. The greater the noise level, the more the analogue signal is disturbed, slowly becoming less usable. Because of this, analogue signals are said to "fail gracefully". Analogue signals can still contain intelligible information with very high levels of noise. Digital circuits, on the other hand, are not affected at all by the presence of noise until a certain threshold is reached, at which point they fail catastrophically. For digital ], it is possible to increase the noise threshold with the use of ] coding schemes and algorithms. Nevertheless, there is still a point at which catastrophic failure of the link occurs.<ref>Richard Langton Gregory, ''Even Odder Perceptions'', p. 161, Psychology Press, 1994 {{ISBN|0415061067}}.</ref><ref>Robin Blair, ''Digital Techniques in Broadcasting Transmission'', p. 34, Focal Press, 2002, {{ISBN|0240805089}}.</ref>
<!--
== Future of analog electronics ==


In digital electronics, because the information is ], as long as the signal stays inside a range of values, it represents the same information. In digital circuits the signal is regenerated at each ], lessening or removing noise.<ref>{{cite book |last=Chen |first=Wai-Kai |title=The electrical engineering handbook |url=https://books.google.com/books?id=qhHsSlazGrQC&q=analog-digital+noise&pg=PA101 |page=101 |year=2005 |publisher=Academic Press |isbn=0-12-170960-4 |quote=Noise from an analogue (or small-signal) perspective...}}</ref>{{failed verification|date=April 2018}} In analogue circuits, signal loss can be regenerated with ]s. However, noise is cumulative throughout the system and the amplifier itself will add to the noise according to its ].<ref>Jon B. Hagen, ''Radio-Frequency Electronics: Circuits and Applications'', p. 203, Cambridge University Press, 1996 {{ISBN|0521553563}}.</ref><ref>Jonathan Davidson, James Peters, Brian Gracely, ''Voice Over IP Fundamentals'', Cisco Press, 2000 {{ISBN|1578701686}}.</ref>
The field of analog electronics nowadays deals with high speed, high performance devices that need the unique advantages provided by analog circuits. Also, digital circuits are an abstraction of analog circuits, but remain analog circuits. As technology progresses and ]s get smaller and smaller, it becomes more and more important when designing digital circuits to account for effects usually present only in analog circuits, requiring expertise in analog circuits.


===Precision===
The range of applications of analog circuits will probably continue to reduce, being replaced by digital circuits because of their smaller size, cheaper cost and easier design. Analog circuits will never cease to exist, but will continue to exist as a specialty field for high performance circuits, or as a high performance part of a digital chip, as integrated circuits with analog and digital circuits in the same ] become more popular.~~~~


A number of factors affect how precise a signal is, mainly the noise present in the original signal and the noise added by processing (see ]). Fundamental physical limits such as the ] in components limits the resolution of analogue signals. In digital electronics additional precision is obtained by using additional digits to represent the signal. The practical limit in the number of digits is determined by the performance of the ] (ADC), since digital operations can usually be performed without loss of precision. The ADC takes an analogue signal and changes it into a series of ]s. The ADC may be used in simple digital display devices, e. g., thermometers or light meters but it may also be used in digital sound recording and in data acquisition. However, a ] (DAC) is used to change a digital signal to an analogue signal. A DAC takes a series of binary numbers and converts it to an analogue signal. It is common to find a DAC in the gain-control system of an ] which in turn may be used to control digital amplifiers and filters.<ref>{{cite book |last=Scherz |first=Paul |title=Practical electronics for inventors |url=https://books.google.com/books?id=nMBtypLEdqgC&q=analog+to+digital+converter&pg=PA730 |page=730 |year=2006 |publisher=McGraw-Hill Professional |isbn=0-07-145281-8 |quote=In order for analog devices... to communicate with digital circuits...}}</ref>
-->

===Design difficulty===

Analogue circuits are typically harder to design, requiring more skill than comparable digital systems to conceptualize.<ref>{{Cite web|title=Clocks - Digital and Analog|url=https://www.mathsisfun.com/time-clocks.html|access-date=2020-12-18|website=Math is Fun }}</ref> An analogue circuit is usually designed by hand because the application is built into the hardware. Digital hardware, on the other hand, has a great deal of commonality across applications and can be mass-produced in a standardised form. Hardware design consists largely of repeated identical blocks and the design process can be highly automated. This is one of the main reasons that digital systems have become more common than analogue devices. However, the application of digital hardware is a function of the ]/] and creating this is still largely a labour-intensive process. Since the early 2000s, there were some platforms that were developed which enabled analogue design to be defined using software - which allows faster prototyping. Furthermore, if a digital electronic device is to interact with the real world, it will always need an analogue interface.<ref>{{cite book |last=Williams |first=Jim |title=Analog circuit design |url=https://books.google.com/books?id=CFoEAP2lwLEC&q=analog+circuit+design+difficulty&pg=PA238 |page=238 |year=1991 |publisher=Newnes |isbn=0-7506-9640-0 |quote=Even within companies producing both analog and digital products...}}</ref> For example, every ] receiver has an analogue preamplifier as the first stage in the receive chain.

Design of analogue circuits has been greatly eased by the advent of software circuit simulators such as ]. IBM developed their own in-house simulator, ], in the 1970s which used an unusual (compared to other simulators) ] method of circuit analysis.

==Circuit classification==
{{broader|Electronic circuit}}
Analogue circuits can be entirely ], consisting of ]s, ]s and ]s. Active circuits also contain active elements such as ]s. Traditional circuits are built from ] elements – that is, discrete components. However, an alternative is ]s, built from pieces of ].


== See also == == See also ==
⚫ *]
* ]
* ] *]
*]
⚫ * ]
*], in contrast to analogue
* ]
*], an analogue chip
* ]
* ] - See here for a discussion of digital vs. analog.


== References == == References ==
{{Reflist}}
<references />


⚫ {{Electronics}}
{{Unreferenced|date=January 2007}}
{{Authority control}}


] ]
⚫ ]
] ]

]
]
]
]
]
]
]
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]

Latest revision as of 12:15, 7 November 2024

Electronic systems with a continuously variable signal

Analogue electronic components like this thermistor function with continuous signals, unlike digital electronics which have discrete signals, usually binary code

Analogue electronics (American English: analog electronics) are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term analogue describes the proportional relationship between a signal and a voltage or current that represents the signal. The word analogue is derived from the Greek word ανάλογος analogos meaning proportional.

Analogue signals

An analogue signal uses some attribute of the medium to convey the signal's information. For example, an aneroid barometer uses the angular position of a needle on top of a contracting and expanding box as the signal to convey the information of changes in atmospheric pressure. Electrical signals may represent information by changing their voltage, current, frequency, or total charge. Information is converted from some other physical form (such as sound, light, temperature, pressure, position) to an electrical signal by a transducer which converts one type of energy into another (e.g. a microphone).

The signals take any value from a given range, and each unique signal value represents different information. Any change in the signal is meaningful, and each level of the signal represents a different level of the phenomenon that it represents. For example, suppose the signal is being used to represent temperature, with one volt representing one degree Celsius. In such a system, 10 volts would represent 10 degrees, and 10.1 volts would represent 10.1 degrees.

Another method of conveying an analogue signal is to use modulation. In this, some base carrier signal has one of its properties altered: amplitude modulation (AM) involves altering the amplitude of a sinusoidal voltage waveform by the source information, frequency modulation (FM) changes the frequency. Other techniques, such as phase modulation or changing the phase of the carrier signal, are also used.

In an analogue sound recording, the variation in pressure of a sound striking a microphone creates a corresponding variation in the current passing through it or voltage across it. An increase in the volume of the sound causes the fluctuation of the current or voltage to increase proportionally while keeping the same waveform or shape.

Mechanical, pneumatic, hydraulic, and other systems may also use analogue signals.

Inherent noise

Analogue systems invariably include noise that is random disturbances or variations, some caused by the random thermal vibrations of atomic particles. Since all variations of an analogue signal are significant, any disturbance is equivalent to a change in the original signal and so appears as noise. As the signal is copied and re-copied, or transmitted over long distances, these random variations become more significant and lead to signal degradation. Other sources of noise may include crosstalk from other signals or poorly designed components. These disturbances are reduced by shielding and by using low-noise amplifiers (LNA).

Analogue vs digital electronics

A digital signal like USB is inherently an analogue signal

Since the information is encoded differently in analogue and digital electronics, the way they process a signal is consequently different. All operations that can be performed on an analogue signal such as amplification, filtering, limiting, and others, can also be duplicated in the digital domain. Every digital circuit is also an analogue circuit, in that the behaviour of any digital circuit can be explained using the rules of analogue circuits.

The use of microelectronics has made digital devices cheap and widely available.

Noise

The effect of noise on an analogue circuit is a function of the level of noise. The greater the noise level, the more the analogue signal is disturbed, slowly becoming less usable. Because of this, analogue signals are said to "fail gracefully". Analogue signals can still contain intelligible information with very high levels of noise. Digital circuits, on the other hand, are not affected at all by the presence of noise until a certain threshold is reached, at which point they fail catastrophically. For digital telecommunications, it is possible to increase the noise threshold with the use of error detection and correction coding schemes and algorithms. Nevertheless, there is still a point at which catastrophic failure of the link occurs.

In digital electronics, because the information is quantized, as long as the signal stays inside a range of values, it represents the same information. In digital circuits the signal is regenerated at each logic gate, lessening or removing noise. In analogue circuits, signal loss can be regenerated with amplifiers. However, noise is cumulative throughout the system and the amplifier itself will add to the noise according to its noise figure.

Precision

A number of factors affect how precise a signal is, mainly the noise present in the original signal and the noise added by processing (see signal-to-noise ratio). Fundamental physical limits such as the shot noise in components limits the resolution of analogue signals. In digital electronics additional precision is obtained by using additional digits to represent the signal. The practical limit in the number of digits is determined by the performance of the analogue-to-digital converter (ADC), since digital operations can usually be performed without loss of precision. The ADC takes an analogue signal and changes it into a series of binary numbers. The ADC may be used in simple digital display devices, e. g., thermometers or light meters but it may also be used in digital sound recording and in data acquisition. However, a digital-to-analogue converter (DAC) is used to change a digital signal to an analogue signal. A DAC takes a series of binary numbers and converts it to an analogue signal. It is common to find a DAC in the gain-control system of an op-amp which in turn may be used to control digital amplifiers and filters.

Design difficulty

Analogue circuits are typically harder to design, requiring more skill than comparable digital systems to conceptualize. An analogue circuit is usually designed by hand because the application is built into the hardware. Digital hardware, on the other hand, has a great deal of commonality across applications and can be mass-produced in a standardised form. Hardware design consists largely of repeated identical blocks and the design process can be highly automated. This is one of the main reasons that digital systems have become more common than analogue devices. However, the application of digital hardware is a function of the software/firmware and creating this is still largely a labour-intensive process. Since the early 2000s, there were some platforms that were developed which enabled analogue design to be defined using software - which allows faster prototyping. Furthermore, if a digital electronic device is to interact with the real world, it will always need an analogue interface. For example, every digital radio receiver has an analogue preamplifier as the first stage in the receive chain.

Design of analogue circuits has been greatly eased by the advent of software circuit simulators such as SPICE. IBM developed their own in-house simulator, ASTAP, in the 1970s which used an unusual (compared to other simulators) sparse matrix method of circuit analysis.

Circuit classification

For broader coverage of this topic, see Electronic circuit.

Analogue circuits can be entirely passive, consisting of resistors, capacitors and inductors. Active circuits also contain active elements such as transistors. Traditional circuits are built from lumped elements – that is, discrete components. However, an alternative is distributed-element circuits, built from pieces of transmission line.

See also

References

  1. Concise Oxford dictionary (10 ed.). Oxford University Press Inc. 1999. ISBN 0-19-860287-1.
  2. Plympton, George Washington (1884). The aneroid barometer: its construction and use. D. Van Nostran Co. aneroid barometer.
  3. Singmin, Andrew (2001). Beginning Digital Electronics Through Projects. Newnes. p. 9. ISBN 0-7506-7269-2. Signals come from transducers...
  4. Miller, Mark R. (2002). Electronics the Easy Way. Barron's Educational Series. pp. 232–239. ISBN 0-7641-1981-8. Until the radio came along...
  5. Hsu, Hwei Piao (2003). Schaum's Outline of Theory and Problems of Analogue and Digital Communications. McGraw-Hill Professional. p. 202. ISBN 0-07-140228-4. The presence of noise degrades the performance of communication systems.
  6. Carr, Joseph J. (2000). Secrets of RF circuit design. McGraw-Hill Professional. p. 423. ISBN 0-07-137067-6. It is common in microwave systems...
  7. Richard Langton Gregory, Even Odder Perceptions, p. 161, Psychology Press, 1994 ISBN 0415061067.
  8. Robin Blair, Digital Techniques in Broadcasting Transmission, p. 34, Focal Press, 2002, ISBN 0240805089.
  9. Chen, Wai-Kai (2005). The electrical engineering handbook. Academic Press. p. 101. ISBN 0-12-170960-4. Noise from an analogue (or small-signal) perspective...
  10. Jon B. Hagen, Radio-Frequency Electronics: Circuits and Applications, p. 203, Cambridge University Press, 1996 ISBN 0521553563.
  11. Jonathan Davidson, James Peters, Brian Gracely, Voice Over IP Fundamentals, Cisco Press, 2000 ISBN 1578701686.
  12. Scherz, Paul (2006). Practical electronics for inventors. McGraw-Hill Professional. p. 730. ISBN 0-07-145281-8. In order for analog devices... to communicate with digital circuits...
  13. "Clocks - Digital and Analog". Math is Fun. Retrieved 2020-12-18.
  14. Williams, Jim (1991). Analog circuit design. Newnes. p. 238. ISBN 0-7506-9640-0. Even within companies producing both analog and digital products...
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