Some Circuit Properties and Applications 

 of n-p-n Transistors 



By R. L. WALLACE, JR. and W. J. PIETENPOL 



Shockley, Sparks, and Teal have recently described the physical properties 

 of a new kind of transistor. Preliminary studies of circuit performance show that 

 it is a stable, high gain, quiet amplifier of considerable practical interest. This 

 paper analyzes the performance of a few early experimental units. 



Introduction 



Almost two years ago, W. Shockley^* ^ first published the theory of a 

 transistor made from a single piece of germanium in which the conductivity 

 type varies in such a way as to produce two rectifying junctions. Since that 

 time, M. Sparks, G. K. Teal and others at the Bell Telephone Laboratories^-^ 

 have contributed notably to the physical realization of this device. 



Recently Sparks has produced a number of n-p-n transistors and has found 

 their behavior to be closely in accord with Shockley's theory.^ Preliminary 

 circuit studies on these devices have shown that in several respects their 

 performance is remarkable. In view of this, our transistor development 

 group has undertaken to produce small quantities of n-p-n transistors in a 

 form suitable for incorporation in working circuits. 



This paper will deal principally with the circuit aspects of the n-p-n 

 transistor by presenting and analyzing performance data on a small number 

 of experimental units. For a discussion of the solid state physics of its design 

 and operation the reader is referred to the previously mentioned works of 

 Shockley, Sparks, and Teal. 



Outstanding Properties 



Before getting lost in a maze of detail, it seems worthwhile to list and 

 mention briefly the salient features of this new transistor. They are: 



1. Relatively low noise figure. Most of the units measured so far have a 

 noise figure between 10 and 20 db at 1000 cps. 



2. Complete freedom from short-circuit instability. The input and output 

 impedances are always positive whether the transistor is connected ground- 

 ed-emitter, grounded-base, or grounded collector. This permits a great deal 

 of freedom in circuit design and makes it possible, by choosing the appro- 

 priate connection, to obtain a considerable variety of input and output 

 impedances. 



3. High gain. Power gains of the order of 40 to 50 db per stage have been 

 obtained 



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