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Need Help: 2V DC to 2V AC conversion at 1 MHz

  1. Sep 3, 2015 #1
    Hi at all,

    I need to convert a DC signal ranging from -2 V to +2V to a AC signal with an amplitude of approximately the same voltage at lets say 1 MHz. The frequency can vary but has be higher than 10 kHz. I looked for PSW inverters but didn't found any suitable.

    Our intention is to record a DC signal (between -2 V and +2V) with an AC coupled DAQ card (Cut-Off 10 kHz).

    best regards and thanks in advance

    Markus
     
  2. jcsd
  3. Sep 3, 2015 #2
    PS: the desired conversion should look like this: 20150903_DCtoAC.png
     
  4. Sep 3, 2015 #3
    This looks like a job for Amplitude Modulation.

    There are lots of potential problems, but it's a very mature technology. Read up on it and if you have questions, ask here.
     
  5. Sep 4, 2015 #4
    Thanks for the quick reply. Problem is solved:

    Built-in amplitude modulation of a function generator. Sorry for not conceiving of this approach from the very first.

    best
     
  6. Sep 4, 2015 #5

    jim hardy

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    re that image attached to post #2

    How will you tell sign ? AC wave for -2 looks just like +2's to me.
     
  7. Sep 4, 2015 #6
    Regarding its magnitude: yes, but it is phase shifted by 180°
     
  8. Sep 4, 2015 #7

    berkeman

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    Seems like a pretty awkward way to digitize that signal. Why are you doing it that way? There are lots of ways to do an isolated ADC arrangement...
     
  9. Sep 4, 2015 #8
    Regarding the system inwhich we would like to implement this DC to AC conversion, another signal defines the acquisition (rate, coupling, ...). Thus, this DC signal needs to be converted to match the acquisition parameters.
     
  10. Sep 4, 2015 #9

    berkeman

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    Is this a school assignment meant to teach you some particular skills, as opposed to a real life design where you would want to optimize the design? Your description of the problem to be solved is quite obscure so far, I must say.
     
  11. Sep 4, 2015 #10
    Sure, but this is just because you don't have any information about our system, which in general is not needed for solving the issue of converting a "DC signal (...) to a AC signal" as asked at the beginning.

    Finally, problem is solved; thanks a lot.
     
  12. Sep 4, 2015 #11

    berkeman

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    Perhaps, but too often inexperienced engineers go down the wrong path trying to design a solution. What they come up with is not as reliable and accurate as could be obtained with a better solution. Isolated ADC conversion is a very proven technology, and likely cheaper and more accurate than the design you have chosen. Just an FYI that is often better to take a step back and look at the overall system when designing circuits. :smile:
     
  13. Sep 4, 2015 #12
    function generator was available - no need to design circuits and loose time and money for the tests we wanted to perform.
     
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