According to the Barkhausen criterion for sustained oscillations, the magnitude of the loop gain βA must be:

Which of the following statements is true for a Colpitts oscillator?

Consider the following statements regarding an RC phase-shift oscillator using a single-stage common-emitter transistor amplifier: I. The amplifier gain is positive (no phase inversion) II. The amplifier gain is negative (introduces 180° phase shift) III. The phase shift introduced by the feedback network is 180° IV. The phase shift introduced by the feedback network is 360° Which of the statements are correct?