THE TRANSISTOR AS A NIOTWOKK KLEMENT 351 



parameters of the transistor and the associatinl oxtcnial cii'cuil will 

 satisfy the following cciuatioii 



2ro Rp ^ 



'1\) eliminate non-essentials it will he assumed that r^ and /'c are neg- 

 hgibly small, and Ha « >',.. Then by a straightforward, hut lengthy, 

 analysis the driving point impedance is found to be 



Z = R, 



p==L'C' + p|' + l 



where L = XL Rf 



R + 4ro 



The circuit representing this impedance is shown in Fig. 15(e). Since 

 negative elements are not convenient a final transformation is made to 

 the circuit shown in Fig. 15(f). 



COXCLUSION 



The distinctive properties of the transistor suggest careful considera- 

 tion of a philosophy which regards the transistor as a circuit element to 

 be introduced at strategic points within a network. Initial work indicates 

 that the judicious interspersion of transistors in a transmission network 

 makes possible performance otherwise unobtainable or uneconomical. 

 This paper has presented examples of how transistors may be used to 

 reduce dissipation, to eliminate inductance, to produce delay, and to 

 invert impedance. Undoubtedly this is only the beginning of exploration 

 which should extend the horizons of network design. 



ACKNOWLEDGEMENT 



The author is indebted to many associates in Bell Telephone Labora- 

 tories, in particular to E. I. Green for basic philosophy and to W. R. 

 Lundry for much helpful advice, and many suggestions, including the 

 novel concepts of non-inductive phase sections and active delay 

 efiualizers. 



