60 NETWORK REALIZATION OF OPTIMUM PERFORMANCE [Ch. 7 



1 ohm 





1 ohm 



+ 



V2 



C/>1; lul>l 

 Det(P - TPTt) = j-^ - l< 0; indefinite 



2uli 



1 ohm 



-1 ohm 



U-<0; lul^l 

 Det(P - TPTt) = - (|-^ + l) < 0; 

 (b) 



+ 

 V2 



indefinite 



V^ -1 ohm 



2w7i 



-1 ohm 



+ 



V2 



0<U<1; |u|<l 

 Det(P - TPTt) =7-T^ - 1 > 0; positive definite 



(c) 



Fig. 7.1. Classes of amplifiers. 



