Analog Electronics. Analog Circuitry Explained
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 pronounced [n](analogos) meaning "proportional".
Analog Electronics. Analog Circuitry Explained
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 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).
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.
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).
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.
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.[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.
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.
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.
RC Low Pass Filter: A common circuit to attenuate high-frequency components in an analog signal is the RC Low Pass Filter. Examine the diagram below, where Vin is the applied voltage and the voltage Vout across C1 is the output.
RC High Pass Filter: A circuit that attenuates low-frequency components in an analog signal is called a RC High Pass Filter. Notice that the circuit is similar to the one above, but Vout is now measured across R1.
Both analog and digital circuits are extensively used in various fields of electrical and electronics engineering for signal processing. Go through this article to find out how analog and digital circuits function and how they differ from each other.
An analog circuit is a type electronic circuit that can process any analog signal or data and produce an output in analog form. Analog circuits are composed of resistors, inductors and capacitors, etc.
The type of signal which is a continuous function of time is known as an analog signal. All the real-world signals are the analog signals, therefore, the analog circuit do not require any conversion of the input signal i.e. the analog input signal can be directly fed to the analog circuit without any loss and it can be directly processed by the given analog circuit. Also, the output signal produced by the analog circuit is an analog signal.
Based on the circuit behavior and the components used, the analog circuit can be of two types viz.: active circuit and passive circuit. Amplifiers are the examples of active analog circuit while low pass filter is an example of passive circuit. The main drawback of the analog circuits is that the analog signals are very susceptible to the noise which may cause distortion of the signal waveform and causing the loss of information.
The basic building blocks of digital circuits are digital logic gates. The digital circuit can process only digital signals, but the real-world signals are of analog nature. Therefore, they need to be converted into digital signals using special electronic circuit known as ADC (Analog to Digital Converter). The output of the digital circuits is also digital signals, which is required to be converted back into the analog signal.
Analog and digital circuits are the two main types of electronic circuits. The key difference between analog and digital circuits is that an analog circuit can process only analog signals, while a digital circuit can process digital signals.
Most of the fundamental electronic components -- resistors, capacitors, inductors, diodes, transistors, and operational amplifiers -- are all inherently analog. Circuits built with a combination of solely these components are usually analog.
Analog circuits can be very elegant designs with many components, or they can be very simple, like two resistors combining to make a voltage divider. In general, though, analog circuits are much more difficult to design than those which accomplish the same task digitally. It takes a special kind of analog circuit wizard to design an analog radio receiver, or an analog battery charger; digital components exist to make those designs much simpler.
Analog circuits are usually much more susceptible to noise (small, undesired variations in voltage). Small changes in the voltage level of an analog signal may produce significant errors when being processed. 041b061a72