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 analogos meaning proportional.[1]
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.[2] 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).[3]
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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.[4]
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.
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.[5] 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).[6]
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 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.[7][8]
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.[9][failed verification] 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.[10][11]
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.[12]
Analogue circuits are typically harder to design, requiring more skill than comparable digital systems to conceptualize.[13] 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.[14] 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.
Electronics is the branch of engineering which deals with the study of devices that function due to the movement of electrons. Based on types of signals used and voltage or current or power ratings, the electronics can be broadly classified into following categories viz.
In this post, we will take a close look at analog electronics and digital electronics and the major differences between them by considering various parameters like definition, type of signal used, current voltage rating, applications, etc.
In analog electronics, two types of components are used to design the systems which are: the active elements such as diode, transistors, etc. and the passive elements such as resistors, capacitors, inductors, etc.
Since both analog and digital electronics are the field of electronics. Although, there are many differences between analog electronics and digital electronics, which are highlighted in the following table-
In this article we will look at some of the most common analogue and digital circuitry used in electronic circuits and PCB design (printed circuit board design). The aim is to give you an overview and understanding of how they work, the advantages and disadvantages of an analogue versus a digital circuit, and when each might be appropriate in circuit design.
Analogue and digital electronic design covers a wide range of potential applications, from simple domestic appliances to complex industrial machinery. In general, an analogue circuit is used for processing continuous signals, while a digital circuit is used for processing discrete signals.
Analogue and digital electronic design are both important disciplines in the world of electronics. Each has its own strengths and weaknesses, and each is suitable for different types of applications. In many cases, the best results can be achieved by using a combination of analogue and digital techniques.
One of the most common types of analogue circuit is the operational amplifier, or op-amp. Op-amps are used in a wide range of applications, from signal conditioning to active filtering. They are usually configured as part of a feedback loop, with the output signal being fed back to the input. This feedback arrangement gives op-amps their unique properties, such as high gain and high input impedance.
Digital circuits, on the other hand, are usually constructed from logic gates. Logic gates are used to implement Boolean functions, which can be used to model any kind of digital circuit. The most common type of logic gate is the AND gate, which takes two input signals and produces an output signal that is high only if both of the input signals are high.
Analogue circuitry is typically used for a signal that is continuous in nature, such as audio or video. However, analogue systems can be more difficult to design and debug, and are usually not as precise as the design of digital circuitry.
Digital circuitry is typically used for a signal that is discrete in nature, such as computer data. Digital circuits are generally more robust than analogue circuits and can be more easily replicated.
In electronic design, an analogue circuit is one that uses voltage or current levels that vary continuously with time to represent signal amplitude. This is in contrast to digital circuits, which use a discrete set of signal levels, usually two voltages or currents, that represent signal amplitude. e24fc04721