PROPERTIES AND APPLICATIONS OF fl-p-fl TRANSISTORS 



541 



tions. This means that stabiUty considerations do not prevent working with 

 matched terminations. Furthermore it is possible to obtain a variety of 

 input and output impedances by connecting the transistor as a grounded- 

 emitter, grounded-base, or grounded-collector stage. It is the purpose of 

 this section to give some idea of the characteristics of these various stages 

 and to show in each case at least one way of supplying the required biases 

 and couplings to the stage. 



Ja 1.00 



qT 

 o 



y 0.96 



o 



u. 



li 0.94 



Q. 



< 



I- 0.92 



Z 



lU 



cc 



§ 0.90 



O ( 



-0.2 -0.4 



-0.6 -0.8 -1.0 -1.2 -1.4 

 le IN MILLIAMPERES 



-1.6 



Fig. 11 — The current amplification factor, a, increases slightly with increasing emitter 

 current. Note the expanded scale for a. 



Table I 

 Constants for Various Transistors Measured at Ve = 4.5 v., /« = 1.0 ma. 



It will be convenient to begin by writing down general relationships which 

 will apply to all the possible connections. To this end let the transistor be 

 represented by the box in Fig. 12. At low frequencies, the signal currents 

 and voltages are related through the equations: 



Riiii + Rnii = Vi 



(4) 



If a generator of open circuit voltage v^ and internal resistance Rg is 

 connected to the input terminals of the device as shown in Fig. 13, then 



Vi = V. 



iiRc 



(5) 



