SHOT NOISE IN DIODES 609 



where I^ is the saturation current and I p is the anode current, and 



(53) 



T?o ^ '^^' ~ yp ^^p ^ '^^' + "V" ^ 10"* ^p. 



where Vp is the anode potential, and T is the absolute cathode temper- 

 ature. 



For T = 900° K, 



.70 = vo' + n.9Vp. (54) 



1.0 



0.9 

 0.8 

 0.7 

 0.6 

 0.5 

 0.4 

 0.3 

 0.2 

 0.1 



4 6 8 10 12 14 16 18 20 22 24 26 28 30 



Fig. 2 — Effective noise generator voltage of planar diode. 



£/- = ^krp{\T)df, rjo' = logey-', 570 = Va' 



kT 



Vr, 



For T = 900° K., rjo = 770' + 12.9 Fp 



Even for the small space charge condition for which the plate current 

 is eight-tenths of the saturation current (tjo' = 0.2), the value of 770 need 

 be greater than about 25 only before X assumes its limiting value. For 

 a temperature of 900° K., as for oxide coated cathodes, this would 

 require a plate voltage of only two volts. If the plate current were less 

 than eight-tenths of the saturation current for very high plate voltages, 

 then as the plate voltage is reduced, r/o' would increase. For this 

 operating condition X maintains its limiting value of 0.644 for all 

 except negative values of plate voltages. 



The transition between the various effective planar diode plate 

 resistance temperatures is more clearly shown in Fig. 3. In this 



