Thermal noise and Johnson–Nyquist noise theory

E175077

Thermal noise and Johnson–Nyquist noise theory is the foundational framework in electrical engineering and physics that quantifies the random voltage and current fluctuations arising from the thermal agitation of charge carriers in resistive components.

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Predicate Object
instanceOf noise theory
physical theory
appliesTo conductors in thermal equilibrium
electrical resistors
resistive components
assumes classical regime where hf << k_B T for white spectrum approximation
thermal equilibrium
contrastsWith flicker noise
shot noise
dependsOn absolute temperature in kelvin
measurement bandwidth in hertz
resistance value
describes Johnson–Nyquist noise
random current fluctuations in resistors
random voltage fluctuations in resistors
thermal noise
explainsCause thermal agitation of charge carriers
field electrical engineering
physics
givesFormula i_rms^2 = 4 k_B T B / R
v_rms^2 = 4 k_B T R B
isIndependentOf applied DC voltage
average current through the resistor
material composition of ideal resistor
isTypeOf equilibrium noise theory
fundamental noise theory in electronics
noiseSpectralDensityFormula S_I(f) = 4 k_B T / R
S_V(f) = 4 k_B T R
predicts frequency-independent noise power spectral density at low frequencies
white noise spectrum over low and moderate frequencies
relatedTo Johnson noise
Nyquist theorem
fluctuation–dissipation theorem
white noise
relatesQuantity absolute temperature
electrical resistance
measurement bandwidth
noise power
states mean-square noise voltage is proportional to bandwidth
mean-square noise voltage is proportional to resistance
mean-square noise voltage is proportional to temperature
symbolForConstant k_B
usedIn communication system noise analysis
low-noise amplifier design
noise figure determination
radio astronomy system design
receiver sensitivity calculations
thermal noise limit calculations for sensors
usesConstant Boltzmann constant

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Full triples — surface form annotated when it differs from this entity's canonical label.

Harry Nyquist notableWork Thermal noise and Johnson–Nyquist noise theory
Harry notableWork Thermal noise and Johnson–Nyquist noise theory
subject surface form: Harry Nyquist
this entity surface form: Thermal agitation of electric charge in conductors (1928 paper)
Harry hasConceptNamedAfter Thermal noise and Johnson–Nyquist noise theory
subject surface form: Harry Nyquist
this entity surface form: Nyquist noise