Transistors in Switching Circuits 



By A. EUGENE ANDERSON 



(Manuscript received August 1, 1952) 



The general transistor properties of small size and weight, low power and 

 voltage, and potential long life suggest extensive application of transistors 

 to pulse or switching type systems of computer or computer-like nature. 

 It is possible to devise simple regenerative circuits which perform the nor- 

 mally employed functions of waveform generation, level restoration, delay, 

 storage {registry or memory), and counting. The discussion is limited to 

 point contact type transistors in which the alpha or current gain is in 

 excess of unity and to a particular feedback configuration. Such circuits, 

 ichich are of the so-called trigger type, are postulated to involve negative 

 resistance. On this basis an analysis, which approximates the negative 

 resistance characteristic by three intersecting broken lines, is developed. 

 Conclusions which are useful to circuit and device design are reached. 

 The analysis is deemed sufficiently accurate for the first order equilibrium 

 calculations. Transistors having properties specifically intended for pulse 

 service in the circuits described have been developed. Their properties, and 

 limitations, and parameter characterizations are discussed at some length. 



INTRODUCTION 



It is proposed to discuss some of the properties of transistors which 

 are appUcable to switching or pulse-type circuits, to develop elementary 

 analysis methods and to describe a few circuits. 



The bounds or limits of the field of switching are diflficult to define. 

 The common thread usually involves definite states of being as "open 

 or closed", "off or on", "0 or 1", and so on, rather than a continuum of 

 conditions. Even when consideration is given to more than two states, 

 the thought involves distinct recognition of each state. The field is 

 termed to be non-linear in distinction to linear manipulation of informa- 

 tion. Any number of anomalies in definition may be raised. 



Without attempting either to define or to limit the field, some of the 

 functions which are often employed are: wave form generation, as 

 rectangular pulses, sawtooth waves, etc.; memory or storage which may 



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