16 



BELL SYSTEM TECHNICAL JOURNAL 



Figure 10 indicates the effectiveness with which the gain of a feed- 

 back ampHfier can be made independent of variations in input ampU- 

 tude up to practically the overload point of the amplifier. These 

 measurements were made on a three-stage amplifier designed to work 

 from 2).2> kc to 50 kc. 



Figure 11 shows that negative feedback may be used to improve 

 phase shift and reduce delay and delay distortion. These measurements 



28 



24 



8 10 12 14- 16 



MILLIAMPERES INTO 600"^ 



Fig. 10 — Ckiin-load characteristic with and without feedback for a low level aiii])lifier 

 designed to amplify frequencies from 3.5 to 50 kc. 



