554 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1951 



If this stage is worked from a zero impedance generator into an infinite 

 impedance load 





(49) 



and so, like a cathode follower, it gives an output voltage which is less than 

 the input voltage, but in the same phase. 

 K the stage is operated into a short circuit 



k = -ix — -^ (50) 



/•e + ^c — r^ 



1 



= — n -. 



1 - « (51) 



= -46.5 ix 



which indicates that the stage can give an appreciable current gain. 

 The input impedance is 



^^-n+r.- /f ' -/"_[ (52) 



When Rl = 0, this reduces to 



Ri = n+ fe (53) 



- n-\- Te 



1 - a 

 = 1445 ohms. 

 When Rl is infinite 



Ri = n-\- To 



= 13.4(10)« ohms. 



(54) 



(55) 



With respect to input impedance, the grounded collector stage is again 

 seen to be like a cathode follower in that the input impedance is high when 

 the load impedance is high. 



The output impedance is 



/?. = r. + r. - r„ - ^'^° ~ !"], (56) 



