I need a circuit that takes in a sinusoidal voltage of given frequency and amplitude,and outputs sinusoidal voltages at 3,5,7 times the frequency of input.Phase and amplitude of output should be variable.

You could use a PLL and some oscillators to do this. You would phase lock to the input and then generate the three outputs. Or you could do it all digitally by sampling your reference signal and then synthesizing the other signals. This gives you the ability to easily change the phase and amplitude of the harmonics. What is it that you are trying to do?

Originally Posted by arunaishus

I need a circuit that takes in a sinusoidal voltage of given frequency and amplitude,and outputs sinusoidal voltages at 3,5,7 times the frequency of input.Phase and amplitude of output should be variable.

Is it for a Sinusoidal power inverter or a Harmonic meter?
Please advise futher... I got some projects that may help you...

I just want a circuit that does that specifically.I am studying harmonic generation and analysis and want some help.I also want to know how I can separate a given waveform into its constituent harmonics without using a spectrum analyser.I guess I could use band pass filters.But I also want to incorporate a display for percetage of 3rd,5th and 7th harmonics in that wave.So kindly give me circuits for that.

For finding the harmonics, you can use a Fourier transform. Since you are looking for specific multiples of the fundamental, you can just compute the parts of the Fourier transform that you need.