Some Circuit Aspects of the Transistor 



By R. M. RYDER and R. J. KIRCHER 



Introduction 



' I ''HE purpose of this note is to discuss in a general way some circuit 

 ■*■ aspects of the transistor. It is rather interesting that in order to discuss 

 its circuit aspects, little direct reference to the transistor is necessary. One 

 needs only certain properties of the transistor which are empirically ob- 

 tainable by measurement; these properties then determine behavior in the 

 manner prescribed by the methods of general network theory. In principle, 

 one needs no knowledge of the physics of the transistor in order to treat it 

 circuitwise; any "black box" with the same electrical behavior at its term- 

 inals would act the same way. 



It is rather fortunate for our purposes that the problem does separate 

 nicely in this way. The operation of the transistor is reasonably well under- 

 stood; but, for calculations of performance from physical properties, the 

 numerical parameters needed are somewhat inaccessible, numerous and com- 

 plicated. The paper by Shockley^ gives some calculations of this kind which 

 are illuminating for theoretical understanding. However, just as with elec- 

 tron tubes, practical engineering calculations often do not need to go back 

 to the ultimate physics. Starting from the electrical properties of the transis- 

 tor as empirically determined by measurements on its terminals, we need 

 go only to the literature of electrical engineering to find much practically 

 useful information on properties of circuits which could be built around the 

 unit. 



This method of characterizing the electrical performance of a device more 

 or less independently of its physical construction has come into wide use 

 in recent years. A considerable amount of work has been done with applica- 

 tions to both electron tubes and transistors at the Bell Telephone Labora- 

 tories by L. C. Peterson.- The purpose of the present note, however, is not 

 to go deeply into the subject but rather to review it in a general way, in- 

 dicating applications to some of the simpler transistor circuits and com- 

 parisons with electron tubes. For more profound analyses one may refer to 

 Peterson's work. 



1 "The Theory of p-n Junctions in Semiconductors and p-n Junction Transistors," 

 \V. Schockley, this issue of The Bell Sysleni Technical Journal. 



^ "Equivalent Circuits of Linear Active Four-Terminal Networks," L. C. Peterson, 

 Bell System Technical Journal, Oct. 1948, pp. 593-622. 



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