Q.Draw the circuit diagram of a RC phase shift oscillator. Draw its output wave form.

An RC phase-shift oscillator uses an op-amp inverting amplifier with three cascaded RC sections in its feedback path, and its output is a steady sinusoidal (sine) wave. …

[!TLDR]

The RC phase-shift oscillator = op-amp inverting amplifier + three $60^\circ$ RC sections; it delivers a sinusoidal output at $f = \dfrac{1}{2\pi\sqrt{6}\,RC}$.

As shown in Figure 6.3.2, the RC phase-shift oscillator consists of an op-amp acting as the amplifying stage and three identical RC sections forming the feedback network from the output back to the inverting input. $R_f$ is the feedback resistor and $R_i$ the input resistor of the inverting amplifier.

Each RC section is adjusted to give a phase shift of $60^\circ$, so the three sections together contribute $3 \times 60^\circ = 180^\circ$. The op-amp, being an inverting amplifier, provides a further $180^\circ$. The total phase shift around the loop is therefore $360^\circ$, which satisfies the phase condition for positive feedback, and the circuit oscillates.

The frequency of oscillation is

$f = \frac{1}{2\pi\sqrt{6}\,RC} = \frac{0.065}{RC}$ …