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Differential input and output op-amps. When do you use them?

Discussion in 'Electronic Design' started by mook johnson, Feb 10, 2013.

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  1. mook johnson

    mook johnson Guest

    I tend to keep things single ended and only on rare occasion have I
    resorted to a differential analog signal.

    When interfacing to a 16+ bit ADC with differential inputs. Then I'll
    generally make the entire circuit differential as far up as practical to
    the sensor.

    Also when the signal has to travel through a wiring harness or pass a
    noisy part of the board.

    I have also played games with psudo-differential with those types of
    input where a dedicated signal reference trace parallel to the feed
    trace (or twisted pair) from the "-" input to the local source "ground"
    when the performance is not THAT critical.

    Are there any other places where a differential signal is key to getting
    the performance and cannot be achieved readily with single ended?
  2. whit3rd

    whit3rd Guest

    If you are concerned with distortion of signal on long transmission lines,
    and pickup/radiation, differential is preferred.

    Long lines, before 1950, meant a few miles.
    In 1970, long lines were a few meters.
    In 2013, long lines are a few centimeters.
  3. miso

    miso Guest

    In leapfrog (ladder) active filter (i.e. continuous time) design, you
    can use a differential output rather than add inverting stages.
  4. Mark

    Mark Guest

  5. josephkk

    josephkk Guest

    More like 50 years old. They had them back in the uA709/uA741 days.

  6. Guest

    Sounds like the uA733 differential-in, differential-out video
    amplifier :)
  7. Guest

    Yes, almost anything that involves a sensor. Anywhere you need to reduce noise which is just about anywhere. One amp to another etc. Strain guages etc
  8. Guest

    If you use a single-ended amp with the standard 4 resistor network for accepting diff inputs, then the impedance seen at the plus and minus inputs are are different for common-mode signals versus diff signals. A diff amp can solve this

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