Answer 6—You keep an amplifier from oscillating by removing one or more of the necessary conditions for oscillation. It’s virtually impossible to entirely eliminate all feedback in an amplifier; and indeed, feedback is an important element in many amplifiers. The amplifier will not oscillate, however, as long as the gain at the frequency where the total phase shift reaches 360° (180° in an inverting amplifier) is less than one, or conversely, if the phase shift at the frequency where the gain drops to unity is less than 360°. These are referred to as the gain margin and phase margin, respectively, of the amplifier.

Contributor: David Tweed