RC Phase Shift Oscillator and Phase Shift Network

RC Phase Shift Oscillator is an electronic oscillator circuit that uses RC phase shift network to provide the required feedback for oscillation. The RC phase shift network consists of several RC circuits connected in series or in parallel.

Phase Shift Network and Phase Shift

The phase shift network provides a phase shift to the output signal, which is necessary for the oscillator to generate a sustained oscillation. The phase shift is a measure of the time delay between the input signal and the output signal.

Phase shift is measured in degrees and can be calculated using the following formula:

Phase shift = (time delay / period) x 360 degrees

Where time delay is the time difference between the input and output signals, and period is the time taken for one complete cycle of the waveform.

Phase Shift in 3-Stage RC Phase Shift Oscillator

In a 3-stage RC phase shift oscillator, each stage of the oscillator provides a phase shift of 60 degrees. Therefore, the total phase shift provided by the three stages is:

Total phase shift = 3 x 60 degrees = 180 degrees

However, the phase shift network also provides a phase shift of 180 degrees due to the fact that it is a high-pass filter. Therefore, the total phase shift provided by the oscillator is:

Total phase shift = 180 degrees + 180 degrees = 360 degrees

Therefore, the oscillator will oscillate at the frequency where the total phase shift is equal to 360 degrees, which is the frequency determined by the values of the resistors and capacitors in the phase shift network.

Conclusion

In a 3-stage RC phase shift oscillator, each stage provides a phase shift of 60 degrees, and the total phase shift provided by the oscillator is 360 degrees. The phase shift network also provides a phase shift of 180 degrees due to its high-pass filter characteristics. The oscillator will oscillate at the frequency where the total phase shift is equal to 360 degrees.