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Analog differential driver

Discussion in 'Electronic Design' started by Michael, Jul 6, 2007.

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  1. Michael

    Michael Guest

    Hi there - I am looking for a good way to drive a board that takes a
    differential analog -10-10V signal. I am using a current output DAC.
    My current plan is to run the current output DAC through a simple
    transimpedance amp (ie http://en.wikipedia.org/wiki/Image:Classic_300.jpg)
    and then pipe that into a op-amp difference amplifier. That'll give me
    one side, but how do I invert it? Sure, I could use an inverting
    amplifier with a gain of 1, but that'd give me a delay between
    transitions, which I would ideally like to avoid. Are there any good
    ways to handle this situation? Maybe is there such thing as an analog
    differential driver chip? When I search for such a beast, I just get
    diff drivers at made by Analog. When I get rid of the Analog results I
    can't seem to find anything. I can't imagine this is *that* uncommon
    of a problem. Suggestions? Argh.

    -Michael
     
  2. Hi there - I am looking for a good way to drive a board that takes a
    Don't google for "analog differential driver", just for "differential
    driver" or "differential line driver".

    There are many differential drivers, from different manufacturers. I can't
    really pin out just one of them, you'll have to compare datasheets and see
    which one is good for your circuit.

    Or, you can build your own differential driver using regular opamps. It's
    not that complicated.. One opamp does noninverting buffering/amplification
    for + signal. The other one is connected as inverting opamp, doing the same
    buffering/amplification for - signal. So, it's symmetrical (enough).

    Using reasonably fast opamps, there's no delay that would have any effect.
    Unless you are using signals which are very fast (like hundreds of MHz).
     
  3. John Larkin

    John Larkin Guest

    Does the dac have diff current outputs? What's its part number?

    How fast does this need to be?

    John
     
  4. Fred Bloggs

    Fred Bloggs Guest

    Right, you just need to *know* how to do it...
     
  5. The standard way of single ended to the differential conversion is using
    the two identical differential amps. One is inverting the signal, the
    other is not inverting. This provides for the completely symmetrical
    configuration. The full differential opamp may be used for that also,
    however there are not too many opamps of this kind.

    You can also find some interesting topologies here:

    http://www.edn.com/article/CA302234.html

    Although their configurations are not strictly symmetrical.


    Vladimir Vassilevsky

    DSP and Mixed Signal Design Consultant

    http://www.abvolt.com
     
  6. neon

    neon

    1,325
    0
    Oct 21, 2006
    You are looking for a hi slew rate differential amp try lm108 i think one side is mark positive the other is mark negative input by the right choice you can get what you want. addi in more amps will add more Tr Tf not desirable .
     
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