1246 THE BELL SYSTEM TECHNICAL JOTTRNAL, NOVEMBER 1952 



100 



75 



«-> 50 



100 200 300 400 500 20 40 60 



RESISTANCE IN OHMS 



100 120 

 XlO^ 



20 



60 SO 

 OHMS 



120 140 

 XIO^ 



2 3 



VOLTS 



80 



0.3 0.4 



I 2 3 4 5 6 7 8 0.1 0.2 



oc oc 



Fig. 23 — Variation in parameters of developmental switching type transistor 

 (M1698). 



these parameters are of little consequence in small-signal applications, 

 they are quite important in switching, particularly Tco . 



Early transistors might exhibit a change in Tco at 60°C of 3 to 1 or 

 more from room temperature values. The transistors of which the data 

 in Figs. 13 and 23 are typical have an Vco temperature coefficient of 

 about —0.75 per cent/°C. That is, the room temperature value of r^o 

 might be reduced by 30 per cent at 70°C. The improved temperature 

 behavior implies a corresponding reduction in variation in trigger 

 sensitivity. Parameter values, large-signal and small-signal, are sho^\Ti 

 in Fig. 24 as a function of temperature. 



