Editing Pink noise (section)

===Electronic devices===
{{Main|Flicker noise}}

The principal sources of pink noise in electronic devices are almost invariably the slow fluctuations of properties of the condensed-matter materials of the devices. In many cases the specific sources of the fluctuations are known. These include fluctuating configurations of defects in metals, fluctuating occupancies of traps in semiconductors, and fluctuating domain structures in magnetic materials.<ref name="Kogan-1996" /><ref name="Weissman-1988">{{cite journal
      | author = Weissman, M. B.
      |year= 1988
      | title = 1/''ƒ'' Noise and other slow non-exponential kinetics in condensed matter
      | journal = [[Reviews of Modern Physics]]
      | volume = 60
      | pages = 537–571
      | doi = 10.1103/RevModPhys.60.537
      | issue = 2
      | bibcode=1988RvMP...60..537W
}}</ref> The explanation for the approximately pink spectral form turns out to be relatively trivial, usually coming from a distribution of kinetic activation energies of the fluctuating processes.<ref name="Dutta-1981">{{cite journal
      |author1=Dutta, P. |author2=Horn, P. M.
      |name-list-style=amp |year= 1981
      | title = Low-frequency fluctuations in solids: 1/''f'' noise
      | journal = [[Reviews of Modern Physics]]
      | volume = 53
      | pages = 497–516
      | doi = 10.1103/RevModPhys.53.497
      | issue = 3
      | bibcode=1981RvMP...53..497D
}}</ref> Since the frequency range of the typical noise experiment (e.g., 1&nbsp;Hz – 1&nbsp;kHz) is low compared with typical microscopic "attempt frequencies" (e.g., 10<sup>14</sup>&nbsp;Hz), the exponential factors in the [[Arrhenius equation]] for the rates are large. Relatively small spreads in the activation energies appearing in these exponents then result in large spreads of characteristic rates. In the simplest toy case, a flat distribution of activation energies gives exactly a pink spectrum, because <math>\textstyle \frac{d}{df}\ln f = \frac{1}{f}.</math>

There is no known lower bound to background pink noise in electronics. Measurements made down to 10<sup>−6</sup>&nbsp;Hz (taking several weeks) have not shown a ceasing of pink-noise behaviour.<ref name="Kleinpenning-1988">{{cite journal
      |author1=Kleinpenning, T. G. M. |author2=de Kuijper, A. H.
       |name-list-style=amp |year= 1988
      | title = Relation between variance and sample duration of 1/f Noise signals
      | journal = [[Journal of Applied Physics]]
      | volume = 63
      |issue=1
       | pages = 43
      | doi = 10.1063/1.340460
|bibcode = 1988JAP....63...43K }}</ref> (Kleinpenning, de Kuijper, 1988)<ref>{{Cite journal |last1=Kleinpenning |first1=T. G. M. |last2=de Kuijper |first2=A. H. |date=1988-01-01 |title=Relation between variance and sample duration of 1/ f noise signals |url=https://pubs.aip.org/jap/article/63/1/43/174101/Relation-between-variance-and-sample-duration-of-1 |journal=Journal of Applied Physics |language=en |volume=63 |issue=1 |pages=43–45 |doi=10.1063/1.340460 |bibcode=1988JAP....63...43K |issn=0021-8979}}</ref> measured the resistance in a noisy carbon-sheet resistor, and found 1/f noise behavior over the range of <math>[10^{-5.5} \mathrm{Hz}, 10^4 \mathrm{Hz}]</math>, a range of 9.5 decades.

A pioneering researcher in this field was [[Aldert van der Ziel]].<ref>Aldert van der Ziel, (1954), ''Noise'', Prentice–Hall</ref>

Flicker noise is commonly used for the reliability characterization of electronic devices.<ref>{{cite journal|url=https://doi.org/10.1016/S0026-2714(02)00347-5|title=Low-frequency noise study in electron devices: review and update|journal= Microelectronics Reliability|author=Hei Wong|date=2003 |volume=43 |issue=4 |pages=585–599 |doi=10.1016/S0026-2714(02)00347-5 |bibcode=2003MiRe...43..585W }}</ref> It is also used for gas detection in chemoresistive sensors <ref>{{cite journal|url=https://doi.org/10.1038/nnano.2013.144|title=Low-frequency 1/f noise in graphene devices|journal= Nature Nanotechnology|author=Alexander A. Balandin|date=2013 |volume=8 |issue=8 |pages=549–555 |doi=10.1038/nnano.2013.144|pmid=23912107 |arxiv=1307.4797 |bibcode=2013NatNa...8..549B |s2cid=16030927 }}</ref> by dedicated measurement setups.<ref>{{cite journal|title=Flicker Noise in Resistive Gas Sensors—Measurement Setups and Applications for Enhanced Gas Sensing|journal=Sensors  |date=2024 |volume=24 |issue=2 |page=405 |doi=10.3390/s24020405|doi-access=free |last1=Smulko |first1=Janusz |last2=Scandurra |first2=Graziella |last3=Drozdowska |first3=Katarzyna |last4=Kwiatkowski |first4=Andrzej |last5=Ciofi |first5=Carmine |last6=Wen |first6=He |pmid=38257498 |pmc=10821460 |bibcode=2024Senso..24..405S }}</ref>