Methods for increasing the stability of resonant amplifiers

There are passive and active methods to increase sustainability.

Passive methods. They are reduced to reducing the actual gain to a value equal to or less stable, so that the inequality is satisfied

This can be done, for example, by decreasing the contour incorporation factors or by decreasing contours.

Find the coefficient of inclusion of the circuit (see Equivalent amplifier circuit in the study of the influence of the internal OS) from the condition (+)

from here

Where ,

        - it is known at the rate of the previous cascade or input circuit.

Coefficient of inclusion is determined from the condition for obtaining the required net attenuation

hence the coefficient

Active methods to improve sustainability.  

Allow to boost and thereby realize the potential amplification capabilities of the lamp or transistor. These methods include:

a) neutralization of the internal operating system of the external operating system;

b) cascade connection of active elements.

              a) Neutralization of internal external feedback.  

The internal OS of the active element can be neutralized using special circuits. If its influence is eliminated, then, in principle, the limitation of the magnitude of the gain coefficient imposed by the stability condition . Then from the amplifier you can get the maximum possible gain, defined by the formula

Where .