What occurs when feedback is lost in an op-amp?

When feedback is lost in an operational amplifier (op-amp), the output will typically saturate. This saturation occurs because the op-amp is designed to amplify the difference between its inverting and non-inverting inputs. Without feedback, there is no mechanism to control this amplification.

In normal operation, feedback regulates the output by feeding a portion of it back to the input, ensuring that the op-amp operates within its linear range. This allows it to produce a stable output that corresponds to the input signal. However, when feedback is removed or compromised, the op-amp can become unresponsive to input changes in a controlled manner, leading it to amplify the input signal to its maximum extent. In this state, the output can reach the power supply rails, resulting in saturation where it may remain at a high or low value depending on the input conditions, but it does not stabilize or provide any meaningful output relative to the input.

In contrast, the other possible outcomes involve more controlled responses that typically occur when some form of feedback is present. Without the influence of feedback, however, the op-amp can no longer respond in a regulated way, resulting in saturation.