Design of a zero crossing detector

[Egor]

Hi Guys,

Have anybody knows how can I do a frequecy phase shift on voltage wave form in a controlled phase radian. This is meant to cascade after a butterworth (2nd order low pass filter) to compensate the time delay response.

Preferably to direct with a schematic. Thanks alot.

:twisted:

 

[crust]

I am not sure I understand your question -- I think what you are saying is that you have a low-pass butterworth which is causing some non-linear phase shift to your signal and you would like to cascade it with another stage that will compensate for the phase shift. Naturally, there is no way to "undelay" the signal, but you can phase shift the rest of the signal by using what is known as an "all pass filter." It basically has frequency response that spans your entire passband but can adjust the phase in your passband. Usually, you end up with a small peak right at the extreme of your passband. In audio signals, that peak turns out to be a few microseconds of delay.