es9018 current mode question

Discussion in 'Analog & Mixed-Signal Design' started by coinmaster, Feb 1, 2018.

  1. coinmaster

    Thread Starter Active Member

    Dec 24, 2015
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    Hi, I'm building an output stage for an es9108 dac running it in current mode by running it into a virtual ground but I have a question about the offset voltage of the virtual ground. Should I have the virtual ground run at 1/2 the dac supply voltage or is it okay if I run it at 0v?
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    IIRC the DAC has differential current outputs and offset voltage is generally not a problem if the amplifiers have a bipolar supply and the output is with in the common mode range.
     
  3. coinmaster

    Thread Starter Active Member

    Dec 24, 2015
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    The output stage is bipolar, I'm just not sure if the dac can achieve it's full dynamic range of current into 0v since it does not have a negative supply.
     
  4. coinmaster

    Thread Starter Active Member

    Dec 24, 2015
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    In the datasheet I found this
    So, that basically means it can work into 0v but there will be a DC current offset if I don't set the virtual ground to 1.65v right?
     
  5. Papabravo

    Expert

    Feb 24, 2006
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    In the application circuits at the end of the datasheet there is a node that is referenced as "Vcm". I wasn't thinking about this in terms of an offset, but it may be. I was thinking in terms of the intrinsic offset voltage of an opamp that is required to get the output to be zero.
     
  6. coinmaster

    Thread Starter Active Member

    Dec 24, 2015
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    How does allowing the dac to produce a DC current offset vs no DC current offset affect performance?
     
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