90 Deg. Phase shifter for 20kHZ square wave

[worksmart]

Hi all,


I have to design a 90 Deg. Phase shifter for a 20kHZ square wave. Can any body share some info. I need a digital circuit solution which should not use R and C. Also shifted wave should have the same timing spec. as original wave( ie PW and period).

Regards
Worksmart

 

[andy1]

Please search the web ... something like "90 phase shifter" ...

I tried it on Google and there are some good ones you can look at.

There are a lot of examples out there.

 

[echo47]

How accurate must it be?

You say 20kHz square wave, but then you say some things that suggest it may not be 20kHz or square. Which is correct?

If it really is a 20kHz square wave, then maybe divicde a 81.92MHz clock by 4096, and output the most significant bit. Detect the leading edge of your input, and use it to preset the counter to 1024. If it's not a square wave, then maybe use a 1024 tap shift register instead.

 

[flatulent]

There is a patented (possibly expired patent) where you get two versions that are different in phase. Then add and subtract these two and limit. Iterate this process and you will get the 90 degrees but not the pulse width of the input signals.