8 



THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1956 



cutoff caused by the collector capacitance and the combined collector 

 body resistance and base resistance is an order of magnitude higher 

 than the measured alpha cutoff frequency and therefore is not too serious 

 in impairing the very high-frecjuency performance of the transistor. 

 This is due to the low capacitance of the collector junction which is 

 seen to be approximately 0.5 mmf at 10 volts collector voltage. The 

 base resistance of this transistor is less than 100 ohms which is quite low 

 and compares very favorably with the best low frequency transistors 

 reported previously. 



The low-frequency characteristics of the double diffused silicon tran- 

 sistor are very similar to those of other junction transistors. This is il- 

 lustrated in Fig. 6 where the static collector characteristics of one of 

 these transistors are given. At zero emitter current the collector current 

 is too small to be seen on the scale of this figure. The collector current 



45 



40 



35 



30 



25 



20 



15 



10 



-5 



2 4 6 8 10 12 14 



CURRENT, If, IN MILUAMPERES 



Fig. 6 — Collector characteristics of a double diffused silicon n-p-n tran- 

 sistor. 



