The description of the phase shift oscillator:

http://www.allaboutcircuits.com/vol_3/chpt_9/4.html

says that the three RC sections each provide 60° of phase shift, but this is not true. As Chet Paynter says:

http://wps.prenhall.com/chet_paynter_introduct_6/0,5779,426330-,00.html

"You would think that each RC network in the phase shift oscillator would produce a 60° phase shift (3 × 60° = 180°), but this is not true. Each RC circuit loads the previous RC circuit, so their phase shifts are not equal. However, the total phase shift must equal 180° for the circuit to operate as an oscillator."

 

Funny you should post that, I was looking at your other thread in the chat forum, followed the same link, and came across this paragraph on the bottom of the section...

The varicap multiplier is primarily used to generate microwave signals which cannot be directly produced by oscillators. The lumped circuit representation in Figure above is actually stripline or waveguide sections. Frequenies up to hundreds of gHz may be produced by varactor multipliers.

Basically a silly spelling error.