Question

In RC phase shift oscillator, one R-C bridge provides ____ phase shift

• A. 30\(^\circ\)
• B. 60\(^\circ\)
• C. 90\(^\circ\)
• D. 180\(^\circ\)

Hint:

RC Phase Shift Oscillator. Uses amplifier (180° shift) and RC network (180° shift). Typically uses 3 RC sections, each contributing approx. 60° phase shift at the oscillation frequency.

Answer 1

The Correct Option is B

An RC phase shift oscillator typically uses an inverting amplifier (providing 180° phase shift) and a feedback network made of cascaded RC sections
To satisfy the Barkhausen criterion for oscillation, the total phase shift around the loop must be 360° (or 0°)
Therefore, the RC feedback network must provide the remaining 180° phase shift
A common configuration uses three identical RC sections (high-pass or low-pass)
For the total network shift to be 180° at the oscillation frequency, each individual RC section must contribute approximately 60° of phase shift
While the phase shift of a single RC section varies with frequency (approaching 90° asymptotically), at the specific frequency where the total shift is 180°, each of the three sections contributes roughly 60°
The term "R-C bridge" is slightly unusual here; it likely refers to one RC section within the phase-shift network