How to achieve 90 degree exact phase shift by using digital circuits?

[bhargav.scsvmv]

How to achieve 90 degree exact phase shift by using digital circuits?

 

[klystron]

Use a shift register as a delay line an tap the signal after a .25 of a period ( 90 degrees)

 

[bhargav.scsvmv]

Use a shift register as a delay line an tap the signal after a .25 of a period ( 90 degrees)

I didn't understand

 

[lostinxlation]

If the signal to be shifted has a period of 4x multiple of the clock, you can use a counter to make it 90 degree shift. But exact 90 degree isn't possible.