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Homework Help: Describing sensors from datasheet information

  1. Mar 11, 2014 #1
    There is a graph of voltage gain against frequency...but it seems like for a gain of 1, that the gain increases after a certain voltage... I know that that doesn't make sense and there is something I dont understand. I have attached a doc with the image from the datasheet in it.
    How do I describe?!


    Attached Files:

  2. jcsd
  3. Mar 11, 2014 #2

    rude man

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    Homework Helper
    Gold Member

    The top trace is the open-loop gain and the bottom trace is the closed-loop gain with unity negative feedback.

    The closed-loop gain can peak at some higher frequencies due to capacitive elements within the device producing some positive feedback. They don't show up at low frequencies because the capacitances look like open circuits at those lower frequencies.

    The open-loop feedback should exhibit steeper slopes as the peaking frequencies are approached. The open loop is of course not data but just a Bode plot whereas the closed loop might be actual data. Only you know for sure ...
  4. Mar 13, 2014 #3
    Hi rude man
    thank you very much!!

    Iv'e attached a datasheet http://www.ti.com/lit/ds/symlink/ina111.pdf .... since there are more than one lines on the graph, what does this mean the graph is showing?
  5. Mar 13, 2014 #4


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    Staff: Mentor

    Welcome to the PF.

    Since this is your schoolwork, you are required to show some effort in answering the questions. What do *you* think is meant by the different traces on the graphs? What specifically is the schoolwork question asking for?

    And the datasheet is for an Instrumentation Amplifier, not a sensor. Can you clarify?
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