The Design of Tetrode Transistor 



Amplifiers 



By J. G. LINVILL and L. G. SCHIMPF 



(Manuscript received March 7, 1956) 



The design of tetrode transistor amplifiers encounters problems of the type 

 that occurs with other transistor uses. Desired frequency characteristics, 

 limitations of parasitic elements, and other practical considerations impose 

 constraints on the range of terminations that can he employed. With many 

 transistors, one can terminate a transistor so that it will oscillate without 

 external feedback; this oscillation or other exceedingly sensitive terminations 

 must be avoided. 



The two-port parameters of the transistor in any orientation in which it 

 is to be used constitute the fixed or given information which is the starting 

 point of the amplifier design. Using this starting point, methods are de- 

 veloped by which one can select, on simple bases, the kinds of terminations 

 that will be suitable. To facilitate the design of amplifiers, a set of charts has 

 been developed from which one can read power gain and input impedance 

 as functions of the load termination. 



Illustrative tetrode amplifiers are described. These include a common base 

 20-mc video amplifier, a common-emitter 10-mc video amplifier, an IF 

 amplifier centered at SO mc, and an IF amplifier centered at 70 mc. Pre- 

 dicted and measured gains are compared. 



INTRODUCTION 



Junction tetrode transistors^ of the type currently produced for re- 

 search purposes at Bell Telephone Laboratories are suitable for high- 

 frequency applications. They are being studied for use in video ampli- 

 fiers, as IF amplifiers where the center frequency is below 100 mc, for 

 oscillators up to 1,000 mc and for very fast pulse circuits. 



Their application in amplifiers brings up design considerations similar 

 to those encountered for other transistors but with differences resulting 



1 R. L. Wallace, L. G. Schimpf and E. Dickten, A Junction Transistor Tetrode 

 for High-Frequency Use, Proc. I.R.E., 40, pp. 1,395-1,400, Nov. 1952. 



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