The Transistor as a Network Element* 



By J. T. BANGERT 



(Manuscript received Octolier 7, 1053) 



The development of the transistor has provided an active element having 

 important advantages in space and power. As a result, the question arises 

 whether strategic insertion of such active elements in passive networks 

 might lead to interesting results. This paper gives a theoretical analysis 

 confirmed by experiment^ of certain possible network applications of tran- 

 sistors. Four general areas are considered in which transistors are used as 

 follows: to reduce the detrimental effects of dissipative reactive elements, to 

 eliminate the necessity for inductors in frequency selective circuits, to pro- 

 duce two terminal envelope delay structures having zero loss, and to invert 

 the impedance of reactive structures. The conclusion is drawn that judicious 

 intcrspersion of transistors in a transmission network enables performance 

 to be achieved which would otherwise be unobtainable or uneconomical. 



INTRODUCTION 



It has become customary through the years to classify hnear circuits 

 as either active or passive. Tiiis convenient, but arbitrary, division has 

 encouraged a philosophy that regards each as a separate and distinct 

 domain. The recent spectacular advances in active devices suggest that 

 in some cases the traditional boundaries should be erased and that a 

 unified approach should be made. 



In particular the de\'elopment of the transistor offers the possibility 

 of interspersing small active elements throughout a passive network to 

 achieve certain desirable effects. This paper intends to survey a few 

 of the ways in which a transistor can be used to advantage in trans- 

 mission networks. The discussion is divided into four parts as follows: 



1. Reduction of dissipation. 



2. Elimination of inductance. 



3. Production of delay. 



4. Inversion of impedance. 



* Presented in part at the Radio Fall Meeting, Toronto, Ontario, Oct. 28, 

 1953. 



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