Hi!

So I have two sine waves, one with phase 0 and another with phase, let's say, pi/4. Now I want to create another sine wave with an amplitude that corresponds to the difference beetwen them. Any ideias? The ideal was that this difference could be converted to amplitude with linear characteristic.

 

You can try doing this in stages.

Firstly, you need a phase comparator. You can do this with a D-type flip-flop or with an XOR gate.
The output will be a PWM signal which you can then integrate to give an analog voltage that is linearly proportional to the phase difference.

From there you can use the analog voltage to modulate the amplitude of a sine wave.

 

You can try doing this in stages.

Firstly, you need a phase comparator. You can do this with a D-type flip-flop or with an XOR gate.
The output will be a PWM signal which you can then integrate to give an analog voltage that is linearly proportional to the phase difference.

From there you can use the analog voltage to modulate the amplitude of a sine wave.

Ok, but how I module the amplitude of a sine wave from the analog voltage?

Thanks!

 

How about subtracting the two in a differential amp as below.
(If you don't mind the resulting sinewave being the same frequency)(?).
One frequency is slightly different than the other to simulate a changing phase shift between the two.