The influence of OOS on the parameters of the amplifier and its characteristics

The influence of OOS on the parameters of the amplifier and its characteristics

Gain
Negative feedback reduces the gain of the amplifier by (1 + βK) times.

If βK >> 1, then the gain taking into account the feedback does not depend on the parameters of the amplifier itself, such feedback is called “deep”


input impedance will increase by - (1 + βK) times
output resistance will decrease by - (1 + βK) times
bandwidth will increase -


Negative feedback increases the stability of the gain, and improves the properties of the amplifier; decreases the level of nonlinear distortion.
Positive feedback properties (PIC)
• U = Uin + Uoc; Kos = K / (1- βK);
• gain, with the introduction of positive feedback increases;
• input impedance decreases;
• output resistance increases;
• bandwidth is narrowed;
• stability of the amplifier deteriorates;
• non-linear distortion increases.

Amplitude-frequency response with feedback

Amplitude response with feedback