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90 degree phase shifter

Discussion in 'Electronic Design' started by jp, Mar 15, 2006.

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  1. jp

    jp Guest

    Hi,

    Does anyone have any suggestions on phase shifting a sinwave by 90
    dgerees. I need to sweep a sinwave from 0 to 500kHz and phase shift it
    by 90 degrees. Any suggestiions would be appreciated.

    Thanks,
    jp
     
  2. Jim Thompson

    Jim Thompson Guest

    It is difficult to do a passive 90° phase shift filter over more than
    about an octave.

    What are you trying to accomplish?

    You might be better off using a quadrature square wave generator
    followed by a tracking filter.

    ...Jim Thompson
     
  3. Thomas Magma

    Thomas Magma Guest

    Most PCI arbitrary waveform generators should be able to do this. There are
    a lot of manufactures of them with all kinds of price ranges and
    functionalities, so you really have to do your homework. Good luck.

    Thomas
     
  4. Tell me, just because I'm nosy, how do you phase shift DC? (0 Hz.)

    What are your REAL requirements?

    Jim
     
  5. John_H

    John_H Guest

    <snip signature>

    Agreed - quadrature generation is the way to go. There are chips from
    Analog Devices (www.analog.com) that do Direct Digital Synthesis complete
    with DACs. A quick scan of the descriptions came up with one quadrature
    device:

    http://www.analog.com/en/prod/0,,AD9854,00.html

    but there may be more.

    - John_H
     
  6. Jim Thompson

    Jim Thompson Guest

    [snip]

    Imaginary DC ?:)

    ...Jim Thompson
     
  7. John Fields

    John Fields Guest

    ---
    An easy, brute force way would be to count through a sine and a
    cosine lookup table, output that data to a couple of DACs and LPF
    the outputs to get rid of the jaggies. View in Courier:

    COUNT SIN ROM SIN DAC
    +------+ +-------+ +-------+
    HFCK>--+--|> Qn|--+--------|An Dn|---|Dn OUT|--[R]--+-->SIN
    | . . | . . . . |
    | . . | . . . . [C]
    | . . | . . . . |
    | | Q0|--|-----+--|A0 D0|---|D0 | GND
    | +------+ | | +-------+ |__ |
    +------------|-----|-------------O|LE |
    | | | +-------+
    | | |
    | | |
    | | | COS ROM COS DAC
    | | | +-------+ +-------+
    | +-----|--|An Dn|---|Dn OUT|--[R]--+-->COS
    | | . . . . |
    | | . . . . [C]
    | | . . . . |
    | +--|A0 D0|---|DO | GND
    | +-------+ |__ |
    +--------------------------------O|LE |
    +-------+
     
  8. John Fields

    John Fields Guest

    ---
    If you do it statically, once you define the rails and the
    relationship between the two outputs, then that relationship will
    exist all the way down to DC:


    COUNT SIN ROM SIN DAC
    +------+ +-------+ +-------+
    HFCK>--+--|> Qn|--+-----+--|An Dn|---|Dn OUT|--[R]--+-->SIN
    | . . | . . . . |
    | . . | . . . . [C]
    | . . | . . . . |
    | | Q0|--+-----|--|A0 D0|---|D0 | GND
    | +------+ | | +-------+ |__ |
    +------------|-----|-------------O|LE |
    | | | +-------+
    | | |
    | | |
    | | | COS ROM COS DAC
    | | | +-------+ +-------+
    | | +--|An Dn|---|Dn OUT|--[R]--+-->COS
    | | . . . . |
    | | . . . . [C]
    | | . . . . |
    | +--------|A0 D0|---|DO | GND
    | +-------+ |__ |
    +--------------------------------O|LE |
    +-------+
     
  9. Well, it's not that you take a sine wave and then sweep it.
    You generate a sinewave, from 0-500Khz. Make your generator
    so that it has 2 outputs, one shifted 90 degrees.

    Sounds like a DDS job.
     
  10. Fred Bartoli

    Fred Bartoli Guest

    Nah. Have two fine wires, one for each signal and a temperature sensor.
    When the first wire comes to 90 deg, then drive the other.
     
  11. Fairly simple. Use a digital sinewave chip, and use the 90 degree
    shifted output pin... :cool:

    Charlie
     
  12. John Larkin

    John Larkin Guest

    The sin() output stays zero, and the cos() stays +1. Forever.


    Incidentally, yesterday. 3.14.2006, was Pi day, and we all missed it.

    John
     
  13. Not true. In its honor I had boysenberry pi for dessert last night.

    Jim
     
  14. I had Pizza Pi - along with 3.1416 pints of beer.
     
  15. Rich Grise

    Rich Grise Guest

    I'd like to see _anybody_ shift a 0 Hz sinewave by _any_ amount! ;-P

    Cheers!
    Rich
     
  16. Jim Thompson

    Jim Thompson Guest

    Naaah! It was in 1593 ;-)

    ...Jim Thompson
     
  17. How about shifting by 1V? Enough? ;-)
     
  18. Fred Bartoli

    Fred Bartoli Guest

    If the sinwave is something you don't have control over, which I doubt since
    you want to sweep it, you can do this but the wide 0-500kHz range makes this
    a bit more complex.

    First you build a wide range 0-500kHz controled oscillator with a 2MHz
    oscillator, a 2-2.5MHz VCO that you mix and LPF so as to obtain your
    0-500kHz range.
    Then you PLL that wide range oscillator to the incoming signal with a mixer
    that'll give you the 90 deg shift.
    The response time would be conditioned by how low in frequency you want to
    go.

    But the better way is as others said: build the quadrature into your
    generator first IOW use a DDS.
     
  19. So, what did you do to celebrate it then?
     
  20. taff

    taff Guest

    Not in the UK, it falls on 31/4/2006

    Taff.......
    ( Thunder Ridge PA, Bristol, UK )
     
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