FEEDBACK AMPLIFIER DESIGN 



453 



In accordance with (7) the maximum available feedback ^m is 

 48 db. For design purposes, however, x and y in (9) were chosen as 

 15 db and 1/5 respectively. This reduces the actual feedback A to 

 about 28 db. The theoretical cutoff characteristic corresponding to 



ao 



m 100 



0.2 0.5 I 2 5 10 20 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 28 — Loop gain characteristic for the amplifier of Fig. 23. 



0.2 0.5 1 2 5 10 20 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 29 — -Loop phase characteristic for the amplifier of Fig. 23. 



these parameters is shown by the broken lines in Figs. 28 and 29, and 

 the actual design characteristic by the solid lines. Since this is a 

 structure in which the required forward gain is considerably less than 

 the maximum available gain, the general course of the cutoff character- 



