Electronic noise

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Electronic noise

Electronic noise is an unwanted signal characteristic of all electronic

Electronics

Electronics refers to the flow of charge through nonmetal electrical conductor , whereas electrical refers to the flow of charge through metal electrical conductor....
circuits. Depending on the circuit, the noise put out by electronic devices can vary greatly. This noise comes from many different electronic effects.

Thermal noise and shot noise are inherent to all devices. The other types depend mostly on manufacturing quality and semiconductor defects.

In some applications, electronic noise can serve a useful purpose.

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Encyclopedia

Electronic noise is an unwanted signal characteristic of all electronic

Electronics

Random number generation

A random number generator is a computer or physical device designed to generate a sequence of numbers or symbols that lack any pattern, i.e. appear random....
.

Types

Shot noise

Shot noise in electronic devices consists of random fluctuations of the electric current

Electric current

Electric current is the flow of electric charge. The electric charge may be either electrons or ions.The International System of Units unit of electric current intensity is the ampere....
in an electrical conductor, which are caused by the fact that the current is carried by discrete charges (electron

Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s).

Thermal noise

Johnson-Nyquist noise (sometimes thermal noise, Johnson noise or Nyquist noise) is the noise generated by the equilibrium

Dynamic equilibrium

A system in dynamic equilibrium is a particular example of a system in a steady state. In a steady state the rate of inputs is equal to the rate of outputs so that the composition of the system is unchanging in time....
fluctuations of the electric current

Electric current

Electrical conductor

In science and Electrical engineering, an electrical conductor is a material which contains movable electric charges. In metallic conductors, such as copper or aluminum, the movable charged particles are electrons ....
, which happens regardless of any applied voltage

Voltage

Electrical tension is the potential difference between two points of an electrical or electronic circuit, expressed in volts. It is the measurement of the potential for an electric field to cause an electric current in an electrical conductor....
, due to the random thermal motion of the charge carriers (the electron

Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s).

The charges may be bound (for a dielectric material) or free (for a conductor). Free charges generate kinetic energy from their motion according to the equation E = (mv²)/2. This kinetic energy results in noise. Bound charges generate kinetic energy when the direction of polarity changes.

This noise is characterized as Additive white Gaussian noise

Additive white Gaussian noise

ExplanationIn Telecommunication, the additive white Gaussian noise channel model is one in which the information is given a single impairment: a linear addition of wideband or white noise with a constant spectral density and a Gaussian distribution of noise samples....
(AWGN) with a noise spectral density

Noise spectral density

In communications, noise spectral density No is the Electronic noise power per unit of bandwidth; that is, it is the power spectral density of the noise....
in watts per hertz of N_o = kT, where k is Boltzmann's constant in joules per kelvin

Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
, and T is the receiver system

System

System is a set of interacting or interdependent entities, real or abstract, forming an integrated whole.The concept of an "integrated whole" can also be stated in terms of a system embodying a set of relationships which are differentiated from relationships of the set to other elements, and from relationships between an element of the se...
noise temperature

Noise temperature

In electronics, noise temperature is a temperature assigned to a component such that the noise power delivered by the noisy component to a noiseless matched resistor is given by...
in kelvins. Since thermal noise can be considered as white noise

White noise

White noise is a random signal with a flat power spectral density. In other words, the signal contains equal power within a fixed bandwidth at any center frequency....
, the total noise power N detected in a receiver with bandwidth B is BN_o.

This phenomenon limits the minimum signal level

Signal level

In a communications system, the signal level is the Signalling Power or intensity at a specified point and with respect to a specified reference level, e.g., 1 mW....
that any radio receiver

Receiver (radio)

This article is about a radio receiver, for other uses see Radio .A radio receiver is an electronics circuit that receives its input from an antenna , uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, electronic amplifier it to a level suitable for further processing, and finally...
can usefully respond to, because there will always be a small but significant amount of thermal noise arising in its input circuits. This is why radio telescope

Radio telescope

A radio telescope is a form of Directional antennae radio Antenna used in radio astronomy and in tracking and collecting data from satellites and space probes....
s, which search for very low levels of signal from star

Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s, use front-end

Front-end and back-end

Front-end and back-end are generalized terms that refer to the initial and the end stages of a process. The front-end is responsible for collecting input in various forms from the user and processing it to conform to a specification the back-end can use....
circuits, usually mounted on the aerial dish

Parabolic reflector

A parabolic reflector is a parabola-shaped Mirror device, used to collect or distribute energy such as light, sound, or radio waves. Parabolic reflectors are used to collect energy from a distant source and bring it to a common Focus , thus correcting spherical aberration found in simpler spherical reflectors....
, cooled in liquid nitrogen

Liquid nitrogen

Liquid nitrogen is a liquefied atmospheric gas produced industrially in large quantities by fractional distillation of liquid air. It is pure nitrogen in a liquid state at very low temperature....
to a very low temperature.

Flicker noise

Flicker noise, also known as 1/f noise, is a signal or process with a frequency spectrum

Frequency spectrum

Familiar concepts associated with a frequency are colors, musical notes, radio/TV channels, and even the regular rotation of the earth. A source of light can have many colors mixed together and in different amounts ....
that falls off steadily into the higher frequencies, with a pink

Pink noise

Pink noise or 1/? noise is a signal or process with a frequency spectrum such that the spectral density is proportional to the reciprocal of the frequency....
spectrum. It occurs in almost all electronic devices, and results from a variety of effects, though always related to a direct current.

Burst noise

Burst noise consists of sudden step-like transitions between two or more levels (non-Gaussian

GAUSSIAN

GAUSSIAN is a computational chemistry software program, first written by John Pople and released in 1970 and has been continually updated for the past 38 years....
), as high as several hundred millivolts, at random and unpredictable times. Each shift in offset voltage or current lasts for several milliseconds, and the intervals between pulses tend to be in the audio range (less than 100 Hz

Hertz

The hertz is a measure of frequency per unit of time, or the number of list of cycles per second. It is the SI base unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts....
), leading to the term popcorn noise for the popping or crackling sounds it produces in audio circuits.

Avalanche noise

See Avalanche diode

Avalanche diode

An avalanche diode is a diode that is designed to go through avalanche breakdown at a specified reverse bias voltage and conduct as a type of voltage reference....
and Avalanche breakdown

Avalanche breakdown

Avalanche breakdown is a phenomenon that can occur in both Electrical insulation and Semiconductor materials. It is a form of electric current multiplication that can allow very large currents to flow within materials which are otherwise good insulators....
.

Measurement

Electronic noise is properly measured in watt

WATT

WATT is a radio station broadcasting a News radio-Talk radio-Sports radio format. Licensed to Cadillac, Michigan, it first began broadcasting in 1945....
s of power

Electric power

Electric power is defined as the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt .When electric current flows in a circuit, it can transfer energy to do mechanical work or work ....
. Because noise is a random process, it can be characterized by stochastic

Stochastic process

A stochastic process, or sometimes random process, is the counterpart to a deterministic process in probability theory. Instead of dealing with only one possible 'reality' of how the process might evolve under time , in a stochastic or random process there is some indeterminacy in its future evolution described by probability distribu...
properties such as its variance

Variance

In probability theory and statistics, the variance of a random variable, probability distribution, or sample is one measure of statistical dispersion, averaging the squared distance of its possible values from the expected value ....
, distribution

Probability distribution

In probability theory and statistics, a probability distribution identifies either the probability of each value of an unidentified random variable , or the probability of the value falling within a particular interval ....
, and spectral density

Spectral density

In statistical signal processing and physics, the spectral density, power spectral density , or energy spectral density , is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has dimensions of power per Hz, or energy per Hz....
. The spectral distribution of noise can vary by frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
, hence its power density is measured in watts per hertz . Since the real power in a resistive

Resistor

|- align = "center"||width = "25"|| |- align = "center"||| Potentiometer|- align = "center"| || |- align = "top"| Resistor|| Variable resistor...
element is proportional to the square of the voltage across the element, noise voltage (density) can be described by taking the square root of the noise power density, resulting in volts per root hertz . Integrated circuit

Integrated circuit

In electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin Wafer of semiconductor material....
devices, such as op-amps

Operational amplifier

An operational amplifier, which is often called an op-amp, is a direct current-Direct coupling high-gain electronic voltage electronic amplifier with differential inputs and, usually, a single output....
commonly quote equivalent input noise level in these terms (at room temperature).

Electronic noise

Types

Shot noise

Thermal noise

Flicker noise

Burst noise

Avalanche noise

Measurement

See also

Further reading