Which of the following is NOT the advantage of R-C phase shift oscillator?

Question

Question

This question was previously asked in

PGCIL DT Electrical 13 Aug 2021 Official Paper (NR I)

It is a fixed frequency oscillator.
By changing the value of R and C, the frequency of the oscillator can be changed.
The circuit is simple to design.
It can produce output over the audio frequency range.

Answer 1

RC phase shift oscillator:

Electrician 25 12Q Oscillators Hindi - Final images Q6

RC phase shift oscillator as shown in the figure is used to invert the input for a 180° phase difference. Hence, the gain of the RC phase shift oscillator is negative.
The single R-C network gives the 60° phase shift. Hence the total phase shift provided by the feedback network is 1800.
In the RC phase shift oscillator, the inverting amplifier produces a 180° phase shift.
The RC Phase shift oscillator has a fixed frequency and is used at lower frequencies.
The circuit is simple to design.
It can produce output over the audio frequency range.
The frequency produced by the above phase shift oscillator is given by:

\(f = \frac{1}{{2\pi RC\sqrt 6 }}\)

Note:

To obtain a phase shift of 180^o at a frequency f, a minimum of 3 highpass RC circuits are needed.
Hence identical RC elements are used to simplify analysis and design.
Also, it is not viable to change circuit elements to get the desired frequency.

Hence changing the value of R and C to get the desired frequency is not the advantage of the R-C phase shift oscillator.