•WS HEI.I. SYSTEM TECHNICAL JOURNAL 



Equivalent Circuit 



/b 



/^ ^r 



mLf "c 



i 



■Zl 



Grounded Base 

 F = 1 + 



4kTBR 

 Grounded Emitter 



1 f— ^. / Z„ + ^. + zt VI 



/•' = 1 + 



■ikTBR 

 Grounded Collector 



+ Z,n + r.,,V _ _ 



Forward F = 1 -\- 





Backward F = 1 + 



AkTBRr 

 1 



Fig. 30 — Noise figure formulas. 



