hello,

I want three phase sine waves. (each separated by 120 deg).
I didnt get proper results from google.
How can i get it from opamps?

And one more thing.
I have XR2206 IC. I can produce a neat sine wave form. How can i shift the phase to get 120deg and 240 deg.

 

you can make phase shift oscillator using opamps or transistors.

http://www.4qdtec.com/wfgz/tpo.gif
http://www.allaboutcircuits.com/worksheets/opamp10.html
http://talkingelectronics.com/projects/200TrCcts/images101-200/3-PhaseSinewave.gif

if the frequency is more or less fixed, you can generate 3-phase digitally and filter outputs. by removing harmonics you get pure sine waves etc.

 

I would first try to make a quadrature output of a sine and cosine wave. Then you can add these together to make the three phase outputs. Two phase to three phase transform equations are well known, and opamp circuits can easily do the math once you have a quadrature signal to work with.

Perhaps an oscillator that gives quadrature outputs is best. One could also try to make a direct 3 phase oscillator, but that is likely more difficult.

http://www.ti.com/sc/docs/apps/msp/journal/aug2000/aug_07.pdf (see Fig. 8)

Your question is a bit open ended though. You haven't specified whether you need to generate this at one frequency, or over a range of frequencies.