SHOT NOISE IN DIODES 



599 



Let 



y = -yau' 



^ ^ F(W) -^f(vo) ^ dF(W) _^ dfivo) 



2 dr]o' 



^ _1_ po [Vy2 ^ ^ _ y-^ 



Vtt Jo '^'^'?) 



^77 c 



dr] 

 dr] 



(22) 



From the definition for r?, given in connection with (13) and (14), 

 it may be shown that 



Vi 



W--^yFi. 



(23) 



where Vi is the a-c. anode potential. With the definition given for 

 a(8) and j8(5) in (11) and (12), and from the above relations, (21) may 

 be rewritten as 



rii'B - 



where 



eVxdfivo) 



kT drjo 



N< 





(C + D)8(uc)duc 



+ 





r^c ^Jy2 -|- r] 8(u,)du,dr] 



^(.v) 



(24) 



' mn 



hm 



Before (24) can be used, the relation between tj/ and the a-c. anode 

 current, and also the expression for the a-c. plate impedance must be 

 obtained. From the general relation given in (1), the instantaneous 

 current per unit area is 



/^OO /♦«! /^X 



/ = e I n{uc)duc — e | no(Uc)du,- + e I 8(uc)duc 



NefT"' -f e 



I 8(Uc)dUc. 



Since the instantaneous voltage of the potential minimum may be 

 expressed as a sum of a d-c. component plus a small a-c. fluctuation, 

 the d-c. and first order fluctuation plate current are respectively 



Jo = Ne€-<, 



Zi = — r]i'Nee~''o' -f e I 8{Uc)du^. 



•7 5i 



(25) 

 (26) 



