Semiconductor Diode Gates 



By LUTHER W. HUSSEY 



(Manuscript received May 22, 1953) 



Diode gates, which are the body of modem pulse communication and 

 computing devices, are discussed. Methods of analysis, by which practical 

 first order design is possible, are given with experimental verification. The 

 general properties of the gates, both virtues and defects, are noted and 

 methods shown for minimizing the defects. 



INTRODUCTION 



Semiconductor diodes are old from the viewpoint of communication 

 engineering. The crystal detector was a fundamental part of the early 

 radio receiver. It was also a troublesome part. The crystals were highly 

 variable and unreliable and there was little theoretical understanding 

 of their physics which could be used as a basis for successfully exploring 

 and controlling their characteristics. While the semiconductor continued 

 to be useful in the field of power rectifiers and the copper oxide modulator 

 later found extensive use in carrier telephone systems, the development 

 of the vacuum tube into a relatively reliable device, with controlled 

 characteristics, tended to eliminate the semiconductor from most of the 

 communication field. 



The copper oxide modulator, in a carrier telephone system, is an 

 early example of the type of application which could bring the semi- 

 conductor back into competition with the tube rectifier. In a radio 

 receiver, the difference in unit cost, power consumption, space require- 

 ments, and maintenance expense, between a tube detector and a crystal, 

 may be small compared with the engineering advantages; but in a tele- 

 phone plant, with its multiplicity of units, each of these small increments 

 of cost may be integrated up to a major item, and may determine the 

 economic feasibility of the whole system. 



The need for better semiconductors than copper-oxide, when carrier 

 frequencies moved up into the megacycle range, was a major stimulus to 

 continue research in the semiconductor field. Within the last few years, 

 physicists, using their recently acquired understanding of the structure 



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