2.7 Noise

2.7.1 Johnson/Nyquist Thermal Noise

This experiment involves measurements of the absolute amount of electronic noise generated by various resistors and a noise diode. The frequency response and bandwidth of the amplifier used and the absolute amount of its mid-frequency gain are first deter mined. From measurements of the thermal noise as a function of resistance and the shot noise as a function of diode current, values of Boltzmann's constant and the electronic charge may be calculated. Thermal noise may also be measured a as a function of temperature, and a value of absolute zero obtained.


  1. J. Johnson, "Thermal Agitation of Electricity in Conductors", Phys. Rev. 32, 97 (1928). This is the original report of experiments on thermal noise in resistors. This effect became known as Johnson or Nyquist noise.
  2. H. Nyquist, "Thermal Agitation of Electric Charge in Conductors", Phys. Rev. 32, 110 (1928). This is the theory of thermal noise published simuntaneously with Johnson's paper.
  3. J. L. Lawson and G. E. Uhlenbech, Threshold Signals, (Dover, New York, 1965). In Grad Lab libary, #16. TK6553.L39 
  4. J. A. Earl, "Undergraduate Experiment on Thermal and Shot Noise", Am. J. Phys. 34, 575 (1966).
  5. P. Kittel, W. R. Hackleman, and R. J. Donnelly, "Undergraduate experiment on noise thermometry," Am. J. Phys. 46, 94 (1978). Rather complete description of the issues. Experiment was based on a PAR 113 preamp, which we use.
  6. W. T. Vetterling and M. Andelman, "Comments on: Undergraduate experiment on noise thermometry," Am. J. Phys. 47, 382 (1979). Shows how to get the measurements with a homemade FET preamp.
  7. Y. Kraftmakher, "Two Student Experiments on Electrical Fluctuations", Am. J. Phys. 63, 932 (1995). Uses a tuned tank circuit used to overcome the lack of a suitable preamp. We have a good preamp, so do not need this trick.
  8. H. D. Ellis and E. B. Moullin, Proc. Cambridge Philos. Soc. 28, 386 (1932).
  9. H. W. Ott, Noise Reduction Techniques in Electronic Systems, New York: John Wiley & Sons, (1976). TK7867.5.087
  10. Jearl Walker, "Noisy Questions: Thermal and Shot Noise," unpublished, 1970.
  11. W. Shockley and J.R. Pierce,"A Theory of Noise for Electron Multipliers," Proc.Ire. 26, 321 (1937)
  12. B.J. Thompson, D.O. Norte, and W.A. Harris,"Fluctuations in Space-Charge-Limited Currents at Moderately High Frequencies," RCA Rev. 4, 269 (1940), 441(1940), 244 (1940), 371 (1940), and 505 (1940).
  13. B.J. Thompson, D.O. Norte, and W.A. Harris,"Fluctuations in Space-Charge-Limited Currents at Moderately High Frequencies," RCA Rev. 6, 114 (1941).


2.7.2 1/f Noise in Metal Films


Shot noise and 1/f noise provide the ultimate limits on signal-to-noise in measurements. The theoretical basis for 1/f noise (so-called because its magnitude increases inversely with the frequency, f) is still a matter of active resea rch. In the Graduate Laboratory, 1/f noise can be demonstrated by measurements of the AC   current through a resistor bridge. The FFT spectrum analyzer can be used to display the frequency components. Great care must be taken, however, to insure that the resist or, and not other components of the measurement circuit, is really the source of the noise.


  1. See http://linkage.rockefeller.edu/wli/1fnoise/ for a bibliography on 1/f noise. History is quite long, going back to W. Schottky (1918) and his original discussions of "shot noise," sometimes now called "Schottkey noise."
  2. D. A. Bell, "A survey of 1/f noise in electrical conductors," J. Phys. C: Solid St. Phys. 13, 4425 (1980). Reviews available ideas and concludes that there are four types of occurence in electrical 1/f noise.
  3. P. Dutta and P. M. Horn,"Low frequency fluctuations in solids: 1/f noise", Rev. Mod. Phys. 53, 3, 497, (1981). Technical review of the 1/f noise in conduction currents.
  4. M. B. Weissman, et al., Rev. Mod. Phys. 60, 2, 537 (1988). Review covers further ideas about the ubiquity of 1/f noise and critically examines various theories. Conclusion: "Overall, a detailed look at 1/f noise in a variet y of materials fails to confirm the initial impression of universality."
  5. B.J. West and M.F. Shlesinger, "The noise in Natural Phenomena," American Scientist, 78, 40 (1990). This is the most recent review but covers a much broader area than just noise in conduction.
  6. D. M. Fleetwood and N. Giordano, Phys. Rev. B 25, 1427 (1982). This paper describes the apparatus used in the following papers.
  7. D. M. Fleetwood, J. T. Masden, and N. Giordano, "1/f noise in plantinum films and ultrathin platinum wires: evidence for a common bilk origin", Phys. Rev. Lett., 50, 450 (1983).
  8. D. M. Fleetwood and N. Giordano, "Resistivity Dependence of 1/f Noise in Metal Films", Phys. Rev. B 27, 667 (1983).
  9. J. H. Scofield and W. W. Webb, "Resistance fluctuations due to hydrogen diffusion in niobium thin films", Phys. Rev. Lett. 54, 353 (1985).
  10. D. M. Fleetwood and N. Giordano, "Direct Link between 1/f Noise and Defects in Metal Film", Phys. Rev. B 31, 1157 (1985).
  11. J. H. Scofield, J. V. Mantese, and W. W. Webb, "1/f Noise in Metals: A Case for Extrinsic Origin", Phys. Rev. B 32, 736 (1985).
  12. H. W. Ott, Noise Reduction Techniques in Electronic Systems, New York: John Wiley & Sons, (1976).  It is call "contact noise" here. TK7867.5.087
  13. SR760/SR770 Spectrum Analyzers Specifications
  14. Lock-In web simulation click here.


Go to Top 
Laboratory Coordinator 
Go to the Handbook Table of Contents 
Dept. of Physics, Univ. of MD


This page was maintained by the Laboratory Staff.

For queries regarding: