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Topic: Johnson noise

	Thermal noise calculation calculator Johnson noise voltage Nyquist dBu dBV - sengpielaudio
		Thermal noise: Also called Johnson noise, is the random white noise generated by thermal agitation of electrons in a conductor or electronic device.
		The Noise factor of a transducer at a specified input frequency is the ratio of (a/b) where "a and b" are:
		It is a specification that helps measure the "quietness" of a gain stage by deriving the equivalent input noise voltage necessary to obtain a given pre amps output noise.
	www.sengpielaudio.com /calculator-noise.htm (442 words)

	Shot noise - Wikipedia, the free encyclopedia
		Shot noise consists of random fluctuations of the electric current in an electrical conductor, which are caused by the fact that the current is carried by discrete charges (electrons).
		Shot noise is to be distinguished from current fluctuations in equilibrium, which happen without any applied voltage and without any average current flowing.
		Low noise active electronic devices are designed such that shot noise is suppressed by the electrostatic repulsion of the charge carriers.
	en.wikipedia.org /wiki/Shot_noise (343 words)

	Converted WP file rhs (Site not responding. Last check: 2007-10-16)
		Johnson suggests that he was simply trying to be heard in a room with three people arguing, and that the fact that he was louder than the others does not support the conclusion that he made unreasonable noise.
		Johnson is correct in his assertion that the volume of his speech is critical in determining whether it was unreasonable within the meaning of IC 35-45-1-3.
		Johnson argues that his right to speak under Article 1, § 9 of the Indiana Constitution was violated by application of the disorderly conduct statute to the facts of this case.
	www.state.in.us /judiciary/opinions/archive/11179904.rhs.html (2200 words)

	Johnson-Nyquist noise - Wikipedia, the free encyclopedia
		Johnson-Nyquist noise (sometimes thermal noise, Johnson noise or Nyquist noise) is the noise generated by the equilibrium fluctuations of the electric current inside an electrical conductor, which happens regardless of any applied voltage, due to the random thermal motion of the charge carriers (the electrons).
		Thermal noise is to be distinguished from shot noise, which consists of additional current fluctuations that occur when a voltage is applied and a macroscopic current starts to flow.
		Thermal noise is intrinsic to all resistors and is not a sign of poor design or manufacture, although resistors may also have excess noise.
	en.wikipedia.org /wiki/Johnson-Nyquist_noise (325 words)

	Electronic News - Noise 101 - 1/8/2004 - EDN - CA371088 (Site not responding. Last check: 2007-10-16)
		Not to be confused with the shape of the noise spectra, the power spectral density is given as a function in units of watts per hertz, allowing you to calculate the rms noise power in a frequency band by integrating the density over a bandwidth.
		In this form, the shot noise appears to have a temperature dependence, but that situation is due to the fact that the dynamic junction impedance—the reciprocal of the transconductance in the case of a bipolar transistor—is linear in temperature.
		Johnson noise has a gaussian amplitude distribution in the time domain and is evenly distributed across the spectrum.
	www.reed-electronics.com /article/CA371088 (2437 words)

	Random Electrical Noise: A Literature Survey
		To verify that a noise source is indeed producing thermal noise, it may be useful to "short out" the source resistance and verify a marked reduction in resulting noise (hopefully to under 1/10 of the original value).
		Thus, the noise is identical to shot noise associated with a dc current twice as large as the reverse saturation current of the diode.
		The noise seems to be generated by a noise current generator in parallel with the dynamic resistance of the diode." (p.
	www.ciphersbyritter.com /RES/NOISE.HTM (8483 words)

	Dataforth - Resistor Thermal Noise
		One common noise category is resistor thermal noise, which is the noise developed in a resistor in the absence of current flow.
		This noise, often referred to as "Johnson" noise, is generated in a resistor independent of any current flow and has a mean-square voltage value of 4kTR(BW).
		For this situation, when the thermal noise in a resistor is shunted by a non-zero capacitance (C), the mean-square voltage value is given by k*T/C. For illustration purposes, consider a resistor at 100 degrees C. with a 1 pico-farad shunt capacitance.
	www.dataforth.com /catalog/doc_1065.html (645 words)

	Johnson-Nyquist noise -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-16)
		It is to be distinguished from (Click link for more info and facts about shot noise) shot noise, which consists of additional current fluctuations that occur when a voltage is applied and a macroscopic current starts to flow.
		It is (A `sh' noise produced by a stimulus containing all audible frequencies of vibration) white noise, in other words.
		Thermal noise at (The normal temperature of room in which people live) room temperature can be estimated in (A logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity) decibels as:
	www.absoluteastronomy.com /encyclopedia/j/jo/johnson-nyquist_noise1.htm (430 words)

	[No title] (Site not responding. Last check: 2007-10-16)
		Flicker noise, typically a noise mechanism that creates a frequency (f) dependent noise voltage inverse in some power of the frequency, can be caused by trapping states in the detector bulk or surface, and by carrier trapping along the channel of the FET amplifier.
		Generation-recombination noise is due to the random nature of the process of creation of a free charge carrier in a detector, and of the subsequent recombination or trapping loss of the carrier.
		It must be remembered that the ultimate noise goal desired is the limit of the noise inherent in the photon stream incident on the detector.
	irtek.arc.nasa.gov /archive/REMCryo93.word (2775 words)

	QUANTUM CALORIMETRY - The basics
		If this so-called phonon noise were the only source of noise, the signal-to-noise ratio would not depend on frequency, and the measurement error could be made arbitrarily small by employing a sufficiently large bandwidth.
		An electrical analog of Brownian motion, Johnson noise is frequency-independent voltage noise that scales with the square root of temperature and resistance.
		Increasing the bias raises the signal and phonon noise relative to the Johnson noise, extending the useful bandwidth, until the decrease in signal-to-noise resulting from self-heating offsets that gain.
	phonon.gsfc.nasa.gov /qcal/qcal_basics.html (811 words)

	LEOT Laser Tutorial - Applications in Photonics and Telecommunications - Module 4: Photodetector Characteristics (Site not responding. Last check: 2007-10-16)
		Shot Noise: The term "shot noise" is normally associated with vacuum tubes in which the stream of electrons creates a noise due to the random fluctuations in the rate of arrival of electrons at the anode.
		Shot noise is present in all photon detectors due to the random arrival rate of photons from the source of radiant energy under measurement and background radiation.
		Measure the noise voltage at a chopping frequency of 1 kHz and a bandwidth determined by the waveform analyzer.
	repairfaq.ece.drexel.edu /sam/CORD/leot/module4/module4.html (6152 words)

	Untitled Page
		The goal of the Johnson noise thermometry program at NIST is to build an electronic temperature standard based on the quantized voltage pulses of superconducting Josephson junctions.
		A stable, programmable, and intrinsically accurate noise source, such as that provided by the QVNS, would provide the advantages of direct calibration of the cross-correlation electronics, matching of the calibration voltage noise to that of the sense resistor, and matching of the source impedance to both the sense resistance and the output transmission-line impedance.
		The Johnson noise power at a known temperature is first balanced with a synthesized noise power from the QVNS.
	emtech.boulder.nist.gov /div817b/whatwedo/jnt/jnt.htm (1804 words)

	Shedding Light on Photodetector Selection
		The excess noise factor is noise added to the output signal by the multiplication process of the APD and is strongly dependent on wavelength as well as gain.
		Since the noise level is proportional to the square root of the frequency bandwidth, the NEP is measured at a bandwidth of 1 Hz and expressed in units of W/Hz But as the light level increases, the NEP no longer plays a role in the signal-to-noise ratio.
		It is the shot noise of the input bias current and the Johnson noise of the feedback resistor.
	www.ptbmagazine.com /articles/shdlght1298 (1498 words)

	Introduction to Quartz Frequency Standards - Noise in Crystal Oscillators
		Although the causes of noise in crystal oscillators are not fully understood, several causes of short-term instabilities have been identified.
		In a properly designed oscillator, the resonator is the primary noise source close to the carrier and the oscillator circuitry is the primary source far from the carrier.
		In the frequency domain, the noise floor is limited by Johnson noise, the noise power of which is kT= -174 dBm/Hz at 290 K. A higher signal (i.e., a higher resonator drive current) will improve the noise floor but not the close-in noise.
	www.ieee-uffc.org /freqcontrol/quartz/vig/vigoscnz.htm (444 words)

	noisepage7
		There are three types of intrinsic noise: Johnson noise, shot noise, and 1/f.
		Johnson noise is the result of thermal fluctuations.
		1/f noise is usually mysterious, associated often with semi conductors in instruments, and intrinsic.
	www.lanl.gov /mst/nhmfl/users/pages/noisepage7.htm (80 words)

	Experiment 8.</head> (Site not responding. Last check: 2007-10-16)
		In spectrophotometric experiments the magnitude of the shot noise on the incident light beam (the random fluctuations in the intensity) determines the ultimate sensitivity of the absorption measurement.
		When signals are weak, the amount of noise can be so great as to cover up the signal completely; that is, the AC fluctuations in the meter will greatly exceed the DC deflection from the signal so that it will be impossible to find and measure the DC signal.
		The frequencies that are found in Shot noise an Johnson noise are broad, and constant in frequency.
	www.chem.brown.edu /chem116/labs/exp8.html (1816 words)

	James A. Moorer's Noise, Sensitivity and Dynamic Range
		The motion of charge is a spontaneous and random flow of the electric charge in the conductor in response to the heat motion of its molecules.
		The voltage between the ends of the conductor varies and is impressed upon the input to the amplifier as a fluctuating noise.
		I thought you might be interested in the "rest of the story" John Bertrand Johnson was a cousin of my father, Dr. John A. Johnson.
	www.jamminpower.com /main/noise.jsp (1576 words)

	Noise - Tutorial - Development Library - National Instruments
		An ideal electronic circuit produces no noise of its own, so the output signal from the ideal circuit contains only the noise that was in the original signal.
		This type of noise is found in all conductors and becomes important in 1C devices because of manufacturing defects.
		The noise spectrum in any given instrumentation system will contain elements of several kinds of noise, although in some systems one form may dominate the others.
	zone.ni.com /devzone/conceptd.nsf/webmain/8DE42E13BD089D8B86256816006545CD?OpenDocument (515 words)

	ChipCenter: The Web's First Definitive Electronics Resource Noise/Chaos/Random Numbers/Linear Feedback Shift Register
		Another example of noise is where Texas Instruments uses a noise source for Artifact Mitigation in their white paper on their Andromeda ASIC all-digital approach to projection display.
		Johnson noise: Thermal agitation of electrons in the resistive portions of impedances results in the random movement of charge through those resistances, causing a voltage to appear corresponding to the instantaneous rate of charge of charge (i.e., current) multiplied by the appropriate resistance.
		White noise: In a white noise spectrum, e-sub-n [Spectral noise density] is constant as a function of frequency....
	www.designer-iii.com /cco/noise/c89r4.htm (3764 words)

	johnson noise - OneLook Dictionary Search
		Johnson noise : The Wordsmyth English Dictionary-Thesaurus [home, info]
		Johnson noise : The American Heritage® Dictionary of the English Language [home, info]
		Johnson Noise : Eric Weisstein's World of Physics [home, info]
	www.onelook.com /?w=johnson+noise&ls=a (121 words)

	SICHROME RESISTOR INFO
		The rise in noise toward low frequencies for the case of 0 V bias is probably due to amplifier noise.
		The noise spectrum of the SiCr on quartz resistor (fl curve) is similar to that of a Victoreen MOX resistor (blue curve) of the same value.
		The horizontal line indicates the Johnson noise predicted from the temperature and resistance, which is in good agreement with the noise for 0V bias.
	www.submm.caltech.edu /~cdd/sichrome/sichrome.html (1475 words)

	Op. amps., quartz resonators, and noise: Johnson Noise
		Electronic noise in circuits is often very difficult to combat when one attempts to make measurements to high precision.
		There are many sources of this electronic noise; here we focus on Johnson Noise.
		Johnson Noise (at a given frequency) is dependent upon two variables: the temperature of the system, and the resistivity in the circuit.
	www.yale.edu /physics/PHYS381_504/JohnsonNoiseWeb/johnson_noise.html (156 words)

	Johnson Pump
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		Most models can be ordered with standard, bevelled or low profiles in order to fit almost any hull and bulkhead configuration, and all are available in either compact or comfort versions so you can outfit your marine lavatory with the perfect-sized toilet, no matter what the layout.
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	www.johnson-pump.com /JPMarine/newsandpressreleases.html (412 words)

	Nanopositioning — Sub-Nanometer Position Noise Measurements — Supplier Data by Mad City Labs
		Johnson noise is considered white noise and is spread evenly across the frequency spectrum with its amplitude proportional to the absolute temperature.
		Observed peak amplitude ratios of 10/1 demonstrate that the random noise amplitude is approximately 1/10 of the one nanometer input signal - equivalent to 0.1 nanometers of position noise.
		Direct noise measurements on Mad City Labs nanopositioning systems as described above have shown that positioning resolutions in the sub-nanometer range are well within the capabilities of the system.
	www.azonano.com /Details.asp?ArticleID=1277 (798 words)

	The Shorthorn Online \| NEWS \| (Site not responding. Last check: 2007-10-16)
		Physical Plant Director Jeff Johnson said students living in nearby residence halls should not be too inconvenienced by the construction.
		Some Brazos House residents said they are worried about the noise, but Johnson said measures to keep the noise down have already been put in place.
		Johnson said he is unsure when that construction will be complete.
	www.theshorthorn.com /archive/2003/fall/03-sep-23/n092303-09.html (454 words)

	ipedia.com: Thermal noise Article (Site not responding. Last check: 2007-10-16)
		In telecommunication or other systems, thermal noise is the noise generated by thermal agitation of electrons in a conductor.
		In telecommunication or other systems, thermal noise (Johnson noise) is the noise generated by thermal agitation of electrons in a conductor.
		The noise power, P, in watts, is given by P = 4kT Δf, where k is Boltzmann's constant in joules per kelvin, T is the conductor temperature in kelvins, and Δf is the bandwidth in hertz.
	www.ipedia.com /thermal_noise.html (215 words)

	Rane Professional Audio Reference (J)
		Johnson noise or thermal noise A form of white noise resulting from thermal agitation in electronic components.
		For example, a simple resistor hooked up to nothing generates noise, and the larger the resistor value the greater the noise.
		It is called thermal noise or Johnson noise and results from the motion of electron charge of the atoms making up the resistor (called thermal agitation, which is caused by heat - the hotter the resistor, the noisier.
	www.rane.com /par-j.html (995 words)

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