Noise Power, Noise Figure And Noise Temperature
Noise Power, Noise Figureand Noise TemperatureMarch 21, 2014Sujeong Lee
Noise Any unwanted input - UNDESIRABLE portion ofan electrical signal Limits systems ability to process weak signals
Noise Power Most of input noise Thermal Noise Noise powerNp kBT BkB Boltzmann s constant 1.38x10 -23 J/KT Absolute temperature of deviceB Circuit bandwidth
Noise Power Signal to Noise Ratio (SNR)S ( f ) average signal powerSNR N ( f ) average noise power
o Soo/No oothe noise figure of the receiver.Noisefigurehas hasnothingto domodulationor urehasnothingtowithdo withwithmodulationor lationformatandof theItisindependentofthemodulationformatandoftion. It is independent of the modulation format andof urefidelity of modulators and demodulators. Noise figure is,is,therefore,a moregeneralconceptthanthannoise-quietingusedto totherefore,aa te the sensitivity of FM receivers or BER used in s.Noise Figure Noise FigureSi/NSSi/Ni ii ――――――――――i/N ―――――――――― ――――――――――GSGS/(N i ii/(Na aaGNi) ii))GS/(N GNGNNaN i iiN aaGN GNGN ―――――― ―――――― GN――――――GNi iiNoisefigureshouldbe thoughtof eNoisefigureshouldbe thoughtthoughtofseparateas al,subsequentgainamplifiessignalnoisenoise isis addedadded toto thethe signal,signal, subsequentsubsequent gaingain amplifiesamplifies signalsignaland andnoisetogetherandanddoesdoesnot notchangethe seratio.availableat theinputto thedeviceuratio.availableat theinputto thedevicrepresentthesignalandnoiselevelsrepresent the signal and noise leFigure1-2(a)showsan examplesituationat theinputof anNa isnoiseaddedby theDUT,anFigure1-2(a)showsan examplesituationat theinputof anNatheis thenoiseaddedby sefloor:DUT.Equation(1-2)showsthedepeamplifier. The depicted signal is 40 dB above the noise floor:DUT. Equation (1-2) shows the deFigure1-2(b)showsthe thesituationat theamplifieroutput.inputNi. Theinputnoiselevelis usuFigure1-2(b)showssituationat theamplifieroutput.inputNi. B. Framplifier’s gain has boosted the signal by 20 dB. It alsosource and is referred to byokToBboostedthe theinputnoiselevellevelby 20thenthenaddedits ownsourcetemperatureof 290K(dboostedinputnoiseby dB20 anddB andaddedits own enceencesourcetemperatureof 290Knoise. The output signal is now only 30 dB above the noiseequivalentto16.8 Cand62.3 F.Thnoise. The output signal is now only 30 dB above the noiseequivalent to 16.8 C and 62.3 Ffloor. Since the degradation in signal-to-noise ratio is 10 dB,average temperature seen by recfloor. Since the degradation in signal-to-noise ratio is 10 dB, the theaverage temperature seen bythe amplifier has a 10 dB noise figure.across the atmosphere at the transmthe amplifier has a 10 dB noise figure.across the atmosphere at the tra Noise figure represents thedegradation in signal/noise66ratio as the signal passesthrough a device.outputinput F is always greater than 1.
Noise FigureNoise Factor Noise FigureModern usage of “noise figure” usually is reservedfor the quantity NF, expressed in dB units:NF 10 log10 F [dB]NF (Si/Ni)dB – (So/No)dBSo/NoSi /Ni(Si/Ni)dB 40 dB(So/No)dB 30 dBNoise Figure 10 dB
Noise Temperature Comes from the random motion of electrons! Thermal Noise Convenient! Common basis for measuringrandom electrical noise from any source Relation with Noise FigureTe To ( F – 1 )Te : The effective noise temperature of deviceT0 : a reference temperature 290K (room temperature)
Summary Noise Power– The magnitude of NoiseNp kBT B Noise Figure– Noise Factor– Noise Figure : the degradation of SNRNF 10 log10 F [dB] Noise Temperature– Basic tool of measuring any kind of noise– Relation with Noise FactorTe To ( F – 1 )
the noise figure of the receiver. Noise figure has nothing to do with modulation or demodula-tion. It is independent of the modulation format and of the fidelity of modulators and demodulators. Noise figure is, therefore, a more general concept than noise-quieting used to indicate the sensitivity of FM receivers or BER used in digital .
Noise Figure Overview of Noise Measurement Methods 4 White Paper Noise Measurements The noise contribution from circuit elements is usually defined in terms of noise figure, noise factor or noise temperature. These are terms that quantify the amount of noise that a circuit element adds to a signal.
7 LNA Metrics: Noise Figure Noise factor is defined by the ratio of output SNR and input SNR. Noise figure is the dB form of noise factor. Noise figure shows the degradation of signal's SNR due to the circuits that the signal passes. Noise factor of cascaded system: LNA's noise factor directly appears in the total noise factor of the system.
Figure 1: Power spectral density of white noise overlaid by flicker noise. Figure 2: Flicker noise generated from white noise. 1.1 The nature of flicker noise Looking at processes generating flicker noise in the time domain instead of the frequency domain gives us much more insight into the nature of flicker noise.
Where F rx is the receiver noise figure, F LNA is the LNA noise figure. F MIX is the mixer noise figure, GLNA is the LNA gain. Assuming that the LNA and mixer are the dominant contributors of noise, if the mixer noise figure is assumed to be 10dB, the maximum noise figure of the LNA is 4.5dB. Maximum swing at ADC output is 0.5V.
extract the noise figure of the DUT from the overall system noise measurement. This step is referred to as second-stage noise correction, as the DUT’s mea-sured noise figure is corrected based on the gain and noise figure of a second stage, which in this case is the test instrument’s noise receiver.
The Noise figure is the amount of noise power added by the electronic circuitry in the receiver to the thermal noise power from the input of the receiver. The thermal noise at the input to the receiver passes through to the demodulator. This noise is present in the receive channel and cannot be removed. The noise figure of circuits in the .
– Noise figure/factor – Gain – Effective temperature – Y-factor – Hot/cold power density The noise figure application utilizes the Y-factor method for calculating noise figure. By using a noise source, X-Series signal analyzers or the MXE EMI receiver can quickly determine the noise of the device under test.
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