Question

In an RC phase shift oscillator using three RC sections, the total phase shift provided by the RC network is

• A. \(90^\circ\)
• B. \(120^\circ\)
• C. \(180^\circ\)
• D. \(360^\circ\)

Hint:

In a three-section RC phase shift oscillator, \[ \boxed{ \text{Each RC section contributes approximately }60^\circ, } \] so the total RC phase shift is \[ \boxed{180^\circ.} \]

Answer 1

The Correct Option is C

Step 1: Recall the phase shift required for oscillation. According to the Barkhausen criterion, the total phase shift around the feedback loop must be \[ 360^\circ. \]

Step 2: Determine the phase shift produced by the RC network. In an RC phase shift oscillator, - the transistor amplifier provides \[ 180^\circ, \] - the three RC sections together provide another \[ 180^\circ. \] Thus, \[ 180^\circ+180^\circ=360^\circ. \] Hence, the RC network contributes \[ \boxed{180^\circ.} \] Therefore, \[ \boxed{(C)} \] is the correct answer.