Analogical electronics

The analogical electronic is the electronic discipline treating of the systems S operative on sizes (tension, running, load) continuous. It differs from the numerical electronic in which these last are quantified. The " term is employed; analogique" because the electric quantities used are with the image of the signal to be treated (similar).

Description

The analogical term is often associated with an electric context, but of other systems such as the Mécanique, the pneumatic , the Hydraulique, etc can also employ analogical signals.

Analogical signals, numeric signals

Information is not coded in the same way in the analogical and numerical circuits. The numerical systems uses the Quantification and a coding of information while the analogical systems work on continuous values.

Historically, the first electronic systems were of analogical type. Those have a simpler structure indeed. The same function will be fulfilled with less components into analogical that numerically. Progress of integration and the rise of the Micro-électronique supported the development of numerical electronics. Analogical electronics, if it appears marginal today remains impossible to circumvent in a certain number of applications.

The principal interest of numerical electronics is its simplicity of operation which makes its behavior very prédictible. The rules of quantification and synchronism (in the circuits Synchronous S) allow to build complex and reliable systems easily. Integration made that possible and inexpensive.

; Noise and precision: Thanks to their quantification, the digital circuits limit the impact of the noise. It is the advantage of coding by “all or nothing”. The analogical signals being continuous, it are obligatorily subjected to an uncertainty due to the fact that the physical signals are convoyed by discrete loads. On the other hand, the quantity of information convoyed on only one wire is larger (at constant frequency).

Immunity with the noise of the digital circuits is very interesting in treatment of the signal. It allows in particular to reach Dynamic S important since this one is limited only by the number of “wire” used to convoy the signal. In analogical it is the ratio between the level of saturation and the noise level which imposes it.

The noise being a physical phenomenon, there remains present in the digital circuits. It is even about one important problem in the recent circuits, which combine the difficulties: small components, weak voltages supplies and high frequencies. The noise is at origin of phenomena being able to put at fault the digital circuits (gigue, Glitch be)

; Integration: Although the digital circuits comprise a great component count and nodes, it are often smaller than them analogical circuits because it lend themselves better to integration. It is less demanding for a Transistor to function into binary (blocked/saturated i.e. closed/open switch) that into linear (amplifier). To make a good amplifier, a transistor in general needs current and to make pass sufficient current while keeping its performances, the transistor must be broad. The digital circuits are small and easier to conceive than the analogical systems. Numerical electronics allows the design of extremely complex circuits such as the Processeurs at a moderate cost.

; Difficulty of design: The digital circuits having a principle of operation simpler, it are easier to conceive. The various parts of a system can also be more easily conceived separately. The analogical design is contrary a delicate art where it is necessary to find a point of balance between a unit compromise. The analogical circuits have much less components but their operation is strongly coupled.

Fields of application

Although numerical electronics is largely present in our lives, the analogical systems are still largely present and essential. They can be gathered in various families:

the sensors : the majority of the Capteur S generate analogical signals representing the physical size to measure.
circuits of instrumentation : the chains of acquisition allow the pretreatment and the amplification of the often weak analogical signals coming from sensors: one speaks about systems of instrumentation
the calculators : in the middle of the 20th century, the analog computers made it possible to carry out mathematical operations by handling analogical signals. They were quickly supplanted by the digital age, nevertheless one always finds circuits being able to carry out such operations: the operational Amplifier .
the filters : one uses still much the analogical filtering when numerical filters, implemented on DSP or FPGA are or too slow (circuits HF) or too heavy to implement. The simplest filter and most known is probably the filter RC.
circuits of electronic amplification : they allow working of analogical signals to be directly usable by actuators: the Amplifying electronics. This sector is competed with by the numerical one, which has a better output when one treats the strong powers.
the actuators : most of the Actionneur S use analogical signals as an order, although those are generally associated with the energy supply of the system: electrical motor, loudspeaker, etc
the converters : finally there exist analogical conversion systems ↔ numerical which one can describe as mixed: EDGE , CNA , MLI .
the oscillators : circuits generating an alternating signal at a fixed frequency. At present, the Oscillating controlled in tension or VCO is a very widespread analogical circuit because of its use in the loops with locking of phase (PLL) and with locking of time (DLL). The oscillators also are very much used for the circuits Radiofréquence.

See too

electronic numerical

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