90 degrees phase shifter circuit

[zeefah]

Moeen,
Could you share the PDF file link please where you found the circuit?

 

[moeen]

Moeen,
Could you share the PDF file link please where you found the circuit?

Sure ,In the wikipedia link you find the circuit as well as in this PDF explanation the design as example, in PDF the example circuit is worked exactly 90 degree pahse shift & unity gain .

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It's all in the wikipedia link.

Hi FvM ,
please i found the example in PDF which i told you previously , and I run the circuit in simulation program and it's OK , but I need to design it in different frequency; RF haven't any equation to design it, and if it remain in the same value , it will not give 90 degree phase shift , Please if you can help me at this point .

With My deepest thanks .
Moeen

 

[FvM]

Hello Moen,

I fear, I didn't exactly understand the problem. The low-pass based all-pass filter has a phase of -2arctan(ωRC), as calculated in your present link, and the high-pass based all-pass filter has a phase of 180°-2arctan(ωRC), as written in the Wikipedia article.

Best wishes,
Frank

 

[moeen]

Hello Moen,

I fear, I didn't exactly understand the problem. The low-pass based all-pass filter has a phase of -2arctan(ωRC), as calculated in your present link, and the high-pass based all-pass filter has a phase of 180°-2arctan(ωRC), as written in the Wikipedia article.

Best wishes,
Frank

Thanks a lot for replay , but the problem with me that : I need another frequency ( I mean that the frequency is not 1.7KHz) as in the example which I found it, and I design the filter as f=1/(2πRC) ; this done ; but RF I remain it as its value in the example which equal to 5.1K ohm , after that when I run the circuit it didn't give 90 degree phase shift , then I predict the problem in RF value , I'm not sure what the problem ??!!! , please if you can give any suggestion to what I must do in this case.

Thanks in advance.
Moeen