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Which of these op amp configurations has the least noise?

  1. May 28, 2014 #1
    I need to run a signal through a configuration so that it has a gain of 1/2. I'm trying to figure out what the best way to minimize the noise for a low frequency input. So far I've only really thought of 3 ways to do this:

    1. Voltage divider into a voltage follower

    2. Measure the input so that I get a negative voltage, and run it through a 1/2 inverting op amp

    3. Run the input through an inverting op amp of -1 gain and then through another one of -1/2 gain

    I believe that, since the frequency is low, I can be very generous with the low pass filter afterwords. Price and (for the most part) power consumption are not factors here, only the accuracy of the signal. I'm pretty new to board level design so any advice would be helpful.

    Thanks!
     
  2. jcsd
  3. May 28, 2014 #2

    Baluncore

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    Science Advisor

    For accuracy and a very precise ratio of ½ you should consider using switched capacitors.
    Linear Technology makes the LTC1043 and the LTC6943.

    Download this data sheet for the LTC1043: http://www.linear.com/docs/3572
    Then look at the applications, “Divide by 2”, page 8, top left.
    Notice the accuracy specified is one part per million.
     
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