NEGATIVE IMPEDANCES AND THE TWIN 21-TYPE REPEATER 489 

 Referring to Fig. 4, the current in the input circuit of the ampHfier is: 



/i 



Ri 



(4) 



Fig. 3 — Curves illustrating properties of series negative resistances. 



The current in the output circuit is: 



e - Mh Ri - M 

 h = B = n D g. 



R2 



R1R2 



(5) 



