90 degree phase shifter for a sine wave with variable frequency

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newbie_hs

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I need to design 90 degree phase shifter for a sine wave of amplitude 1V and frequency varies from 5Khz to 50Khz I found some solutions here itself.
In all those approaches amplitude varies with frequency.

I need constant amplitude at all these frequency range.May I know any circuit ideas.
 

Solution
FvM
Tracking all-pass filter can basically achieve what you want

1743331265684.png

Brief desciption
- U1 forms programmable low-pass (gm-C filter)
- C3/R15 cancels DC offset
- U2 combines low-pass output with input signal forming an all-pass
- U3, U4 + XOR A1 measures phase shift, XOR output has 50 % duty cycle at 90 degree
- U5 integrates error signal
- R16/R4 reduces 2*f0 ripple that causes signal distortion at low signal frequencies
- control signal tunes low pass

Example waveform, settling for 10 kHz input:

1743332217987.png
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facepalm

This is why FvM clearly asked if a differential phase shift was acceptable.

The short answer is no, there's no way to create broadband phase shift with analog circuits.

However in practice there is probably no need to do so. If you explained why you need this phase shift and what role it plays in your system, it's likely we can find a way to get what you want.

newbie_hs said:
@barry
I agree.Can I use this IC for my application.
Click to expand...
No, that will not help you.
 
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mtwieg said:
If you explained why you need this phase shift and what role it plays in your system, it's likely we can find a way to get what you want.
Click to expand...
I will check one more time with the team(Optics Team).What they told me is that they have an input sine wave of frequency which varies from 5K-50Khz and they need
a system which will do a 90 degree phase shift of this signal.I will discuss with them again,try to get the full information about their system and will update here.
 

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Requirements aren't actually clear. Discussed all-pass chains are used for complex signals, e.g. speech or other audio. If you have a monofrequent sine, there are probably simpler methods. It's however no clear what's the significance of magnitude ("1V"). If the problem is only about keeping it constant, an ALC circuit can do the trick.
 
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I had a discussion with the team again.The requirement is same.Let me tell the requirement one more time here.
They have a sine wave of frequency 5Khz to 50Khz with an amplitude of 1V.I need to design a circuit which will phase shift this input signal by 90 degree.
 

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Phase error 0.5 degree(not finalized).
Even they don't have any idea about the other things.
First I need to make a simple proto
 

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An interesting problem for absolute phase accuracy whilst maintaining amplitude by AGC, is that amp BW may add its own phase lag dependence on the gain-setting (a fair bet when varying by either bias current or gain-node impedance).
 

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FvM said:
Output signal:
- should track input magnitude
- should maintain 1 V (pk, rms ?) independent of input magnitude
- either of both
Click to expand...
I checked again if "output amplitude little less than 1V if also fine,we can amplify the phase shifted signal". this is what I received.Initial intention is to create phase shifted signal
 

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Where does Sine in come from? Sig Gen, VCO? S/W?
It is better to create IQ from 2f then convert to sine or use Nxf then IQ then convert each to sine using R-DAC /N registers for perfect phase.
Do you agree?

Does DC bias matter?
 

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how fast does the frequency change? Or Is it static? What is the required response time? I’m thinking a digital solution might be simplest.
 

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D.A.(Tony)Stewart said:
Where does Sine in come from? Sig Gen, VCO? S/W?
It is better to create IQ from 2f then convert to sine or use Nxf then IQ then convert each to sine using R-DAC /N registers for perfect phase.
Do you agree?

Does DC bias matter?
Click to expand...
Sine wave comes from Function generator.
--- Updated ---

barry said:
how fast does the frequency change? Or Is it static? What is the required response time? I’m thinking a digital solution might be simplest.
Click to expand...
Sine wave frequency is 5Khz to 50khz
 

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You could also make several fixed-f quadrature IQ-Sine oscillators Vp controlled by Vref or AGC (tbd) "Phase shift Oscillator"


https://tinyurl.com/2ya2zl83 <= online sim.

If you do not think harder about your design specs and answer my questions this is going to sound like an immigration interrogation.
 
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newbie_hs said:
Sine wave comes from Function generator.
--- Updated ---


Sine wave frequency is 5Khz to 50khz
Click to expand...
That's not what I asked. I asked how fast the frequency changed, not what the range was.
newbie_hs said:
Input is coming from external world like function generator.
Click to expand...
You know, they make frequency generators with quadrature (90 degree) outputs...
 

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