174 BELL SYSTEM TECHNICAL JOURNAL 



and produces a noise plate current (for zero load resistance) 



i^ = ^kTRnBGK (72) 



Comparing (69) with (72) we find 



Rn = (.644/G) {TJT,). (73) 



Here To is a reference temperature, usually taken as 290° K. The effect of 

 load impedance on signal from this fictitious resistance is treated by purely 

 circuit means. 



In pentodes there is noise according to (69) and in addition there is par- 

 tition noise according to (33). By taking P from (70) and equating the 

 noise current given by {?)?)) to (72) the fictitious "noise resistance" of a 

 pentode can be evaluated in terms of g, Ip/h and Tc/T. 



References 



1. S. O. Rice, "Mathematical Analysis of Random Noise," B. S. T. /., XXJII, pp. 



282-332, July 1944, and XXIV, pp. 46-156, January, 1945. 



2. D. A. Bell has given a valuable summary and discussion of noise and especially of noise 



in vacuum tubes. "Fluctuations of Electric Current," Journal of the I. E. E., 

 Vol. 93, pt. 3, pp. 37-44, January 1946. 



3. J. B. Johnson, "Thermal Agitation of Electricity in Conductors," Fhys. Rev., Vol. 



32, No. 1, pp. 97-109, July (1928). 



4. H. Nyquist, 'Thermal Agitation of Electric Charge in Conductors," Phys. Rev., 



Vol. 32, No. 1, pp. 110-113, July (1928). 



5. W. Schottky, "Spontaneous Current Fluctuations in Various Conductors," Ann. 



Physik, 57, pp. 541-567, (1918). 



6. Irving Langmuir and Karl T. Compton, "Electrical Discharge in Gases," Part II, 



Rev. Mod. Phys., Vol. 3, ^2, p. 226 (April 1931). 



7. W. Shockley and J. R. Pierce, "A Theory of Noise for Electron Multipliers," Proc. 



L R. E. 26, pp. 321-332, March 1938. 



8. B. J. Thompson, D. O. North and W. A. Harris, "Fluctuations in Space-Charge- 



Limited Currents at Moderately High Frequencies" 

 Part I—R. C. A. Review, Jan. 1940 

 Part II— " Apr. and July 1940 



Part III— " Oct. 1940 



Part IV— " Jan. 1941 



Part V— " Apr. and July 1941. 



9. A. J. Rack, "Effect of Space Charge and Transit Time on the Shot Noise in Diodes," 



B. S. T. J., Vol. 17, No. 4, p. 592, October (1938). 



10. W. Schottky, and E. Spenke, "The Space-Charge Reduction of Shot Effect," Wis- 



senschaftliche V erofenllichungen aus den Siemens-Werken, Vol. 16, No. 2, pp. 1-41, 

 July (1937). 



11. E. Spenke, "The Space-Charge-Reduction of Shot Effect," Wiss. Verof. atis den 



Siemens-Werken, Vol. 16, No. 2, p. 19, July (1937). 



