SHOT NOISE IN DIODES 



617 



The effect of transit time on the pure shot noise for a low space 

 charge density and a high plate voltage may be obtained quite readily 

 from (57) and (58). Since for a very small space charge, Jo and Ua are 

 small, and a„ large, the equations then reduce to the following ex- 

 pression : 



Vi = ^ — +-7^a„r- 



1 



- iiee~''> + e- 



1) 



(71) 



1 23456789 10 II 



TRANSIT ANGLE IN RADIANS 



Fig. 4 — Effect of transit time on both thermal and shot tube noise. 



E/ = 4SkiOM4:T)rpdf, 

 7/ = leSIodf. 



For these operating conditions, the transit time in terms of the d-c. 

 acceleration and the electrode spacing is given by 



X = 



tta T- 



In terms of the external circuit impedance Z/ 



(72) 



