Flicker noise is a type of electronic noise with a 1/f, or pink power density spectrum. It is therefore often referred to as 1/f noise or pink noise, though these terms have wider definitions. It occurs in almost all electronic devices, and can show up with a variety of other effects, such as impurities in a conductive channel, generation and recombination noise in a transistor due to base current, and so on. 1/f noise in current or voltage is always related to a direct current because it is a resistance fluctuation, which is transformed to voltage or current fluctuations via Ohm's law. In mechanics, it was found in the earth’s rate of rotation, undersea currents and the hourglass flow of sand fluctuations.
In electronic devices, it shows up as a low-frequency phenomenon, as the higher frequencies are overshadowed by white noise from other sources. In oscillators, however, the low-frequency noise can be mixed up to frequencies close to the carrier which results in oscillator phase noise.
Flicker noise is often characterized by the corner frequency fc between the region dominated by the low-frequency flicker noise and the higher frequency "flat-band" noise. MOSFETs have a higher fc (can be in the GHz range) than JFETs or bipolar transistors which is usually below 2 kHz for the latter.
The flicker noise voltage power in MOSFET can be expressed by K/(Cox•WLf), where K is the process-dependent constant, Cox is the oxide capacitance in MOSFET devices, W and L are channel width and length respectively.
Flicker noise is found in carbon composition resistors, where it is referred to as excess noise, since it increases the overall noise level above the thermal noise level, which is present in all resistors. In contrast, wire-wound resistors have the least amount of flicker noise. Since flicker noise is related to the level of DC, if the current is kept low, thermal noise will be the predominant effect in the resistor, and the type of resistor used may not affect noise levels, depending the frequency window.
Other articles related to "flicker noise, noise":
... For DC measurements 1/f noise can be particularly troublesome as it is very significant at low frequencies, tending to infinity with integration/averaging at DC ... At very low frequencies, you can think of the noise as becoming drift, although the mechanisms causing drift are usually distinct from flicker noise ... This filtering of DC also attenuates the flicker noise ...
... Flicker noise, also known as 1/f noise, is a signal or process with a frequency spectrum that falls off steadily into the higher frequencies, with a pink ...
... Tuning range, tuning gain and phase noise are the important characteristics of a VCO ... Generally low phase noise is preferred in the VCO ... The noise present in the control signal and the tuning gain affect the phase noise high noise or high tuning gain imply more phase noise ...
Famous quotes containing the words noise and/or flicker:
“You have to make more noise than anybody else, you have to make yourself more obtrusive than anybody else, you have to fill all the papers more than anybody else, in fact you have to be there all the time and see that they do not snow you under, if you are really going to get your reform realized.”
—Emmeline Pankhurst (18581928)
“Billboards, billboards, drink this, eat that, use all manner of things, everyone, the best, the cheapest, the purest and most satisfying of all their available counterparts. Red lights flicker on every horizon, airplanes beware; cars flash by, more lights. Workers repair the gas main. Signs, signs, lights, lights, streets, streets.”
—Neal Cassady (19261968)