For a system to work, as oscillator the total phase shift of the loop gain must be equal to

• 90°
• 45°
• 270°
• 360°

Correct Answer: 360°

Explanation:

Gain of system with + ve feedback = for oscillation

but V₀ ≠ 0

so, that 1 - AB = 0 ⟹ AB = 1 ∠0° or 360°.