What is required of a circuit to have oscillation?
Answer Positive feedback is required to cause oscillation in an amplifier. It can be a small amount of positive feedback. Positive feedback means that some of the output goes back to the input and then increases the output. This continues, so the output steadily increases. If we are takiing about an AC amplifier, then the output oscillation amplitude increases. (The instantaneous voltage can be positive or negative, “positive” feedback just means that the output is going the same direction as the input). Normally, a feedback amplifier, like an op-amp, uses negative feedback. To get around to positive feedback, that means there was a 180 degree phase shift. Hope this helps!
