<P> When the oscillation frequency is high enough to be near the amplifier's cutoff frequency, the amplifier will contribute significant phase shift itself, which will add to the phase shift of the feedback network . Therefore the circuit will oscillate at a frequency at which the phase shift of the feedback filter is less than 180 degrees . </P> <P> The single op - amp circuit needs a relatively high gain (about 30) to maintain the oscillation due to the RC sections loading each other . If each RC segment did not affect the others, a gain of about 8 to 10 would be sufficient for oscillation . An isolated version of the oscillator can be made by inserting an op - amp buffer between each RC stage . (This also simplifies the modeling equations .) </P>

Explain the operation of rc phase shift oscillator