phase shift oscillator (Formula)

[Ghasemzadeh]

**broken link removed**
I want to find phase shift between A and B output (and also A-C & A-D)
I use EWB to find phase shift but I need Formula for phase shift and also gain of A-B (not in dB)(A-C & A-D) (Gain VB/VA VC/VA VD/VA)
Any one can help me to find formula of gain and shift phase?

 

[audioguru]

You should use a buffer amplifier between each RC phase-shift section so that the next RC section doesn't load-down the previous section. Then the calculations are simple and the gain of the inverting opamp does not need to be so high.

 

[Ghasemzadeh]

You should use a buffer amplifier between each RC phase-shift section so that the next RC section doesn't load-down the previous section. Then the calculations are simple and the gain of the inverting opamp does not need to be so high.

Thanks,I want to know how can I find gain (loss) in this circuit.
Just tell how can I find Voltage of A and B I can do it for other nodes.

 

[audioguru]

Texas instruments has a document about sine-wave oscillators. Their simple phase-shift oscillator has the R and C reversed from your circuit (as lowpass filters to reduce distortion) and say that theirs needs a gain of 27 to start oscillating. If the RC stages are buffered then the gain must be slightly more than 8.