Which type of feedback is critical for sustaining oscillations in an oscillator circuit?

In an oscillator circuit, positive feedback is essential for sustaining oscillations. Oscillators rely on the principle of continuously amplifying an input signal to develop a periodic output waveform. For this amplification process to continue, the feedback from the output of the oscillator must be fed back to the input in such a way that it reinforces or enhances the original signal.

When positive feedback is applied, a portion of the output signal is fed back in phase with the input signal, effectively increasing the overall gain of the circuit. This continuous reinforcement allows the output to grow until it stabilizes at a certain amplitude, producing sustained oscillations. In contrast, if negative feedback were applied, it would reduce the output signal, potentially leading to a decrease in amplitude and eventual cessation of oscillations.

In summary, positive feedback is critical in oscillator circuits as it enables the necessary conditions for maintaining consistent oscillating behavior.