Inverse of the Gibbs Phenomenon to generate a sine wave I am a quite new to the area of digital signal processing. I am currently doing a project on sine wave generation. I know that according to Gibbs phenomenon, many sine waves add up to form a square wave. So, square wave would contain many frequencies. If we filter that square wave stage by stage using low pass and band pass filters, will I be able to get a sine wave at expected fundamental frequency? Please help.
Square waves are composed of sine waves at the odd harmonics- i.e. 1st, 3rd, 5th, etc.  So yes, you can produce a sine wave from a square wave if you filter it with a low-pass filter whose bandwidth is at least as big as the first harmonic frequency, and whose cutoff frequency is lower than the third harmonic.