SOME ciRcnr asi'kcts or run transistor 



ilS 



above with the triode equivalent circuit of F. B. Llewellyn and L. C. I'eter- 

 son^ in Fig. 9. Both circuits have the same topological form, and have 

 similar impedance levels if the triode is considered to be operating in the 

 frequency range of some tens of megacycles. The most important difference 

 concerns the quantity a, a current ampUfication factor which, for the tran- 

 sistor, mav be considerably greater than unity; while the analogous quantity 



V 



Can be stable if: 



X 



Re Ri Re 



R's include resistive elements both internal and external to the transistor. 



Fig. 8— Stability 



TRANSISTOR 



a If 



a > 1 USUALLY 



Fig. 9 — Transistor-electron tube analogy. 



for the triode is close to unity for usual conditions. Another difference, of 

 less importance, is the fact that the tube quantities analogous to re and n, 

 are capacitative reactances; their ratio, however, is like the ratio of r^ to rb 

 in magnitude. 



One of the first consequences of this transistor-tube analogy is the sugges- 

 tion that different transistor connections analogous to the different electron 

 triode connections may be interesting.^ The analogy makes emitter analogous 



^"Vacuum Tube Networks," F. B. Llewellyn and L. C. Peterson, Fror. LR.E.. March 

 1944, page 159, Fig. 13. 

 ^Loc. cit. 



